JP5046538B2 - Eye-safe laser light source and electronic device using the same - Google Patents

Description

  The present invention relates to a technique for making a semiconductor laser light source eye-safe, and more particularly to an eye-safe laser light source capable of obtaining a large apparent light source diameter (apparent light source diameter) while maintaining high radiation intensity.

  A laser light source used for optical communication or illumination needs to satisfy safety for eyes, and the maximum allowable radiation intensity of the laser light source is defined by the IEC standard or the like.

  The maximum allowable radiation intensity that a laser light source can radiate into the space while satisfying eye safety depends on the laser wavelength λ and drive conditions (laser current, light output, etc.), but the intensity of the apparent light source mainly determines the intensity. It is known to do.

  FIG. 15 shows the relationship between the diameter of the apparent light source and the maximum allowable radiation intensity based on the international safety standard IEC 60825-1.2 regarding the laser light source. From this figure, it can be seen that the maximum allowable radiation intensity can be increased by increasing the diameter of the apparent light source. It can also be seen that the increase in the maximum allowable radiation intensity with respect to the enlargement amount of the apparent light source diameter is remarkably large in the region where the apparent light source diameter size is 2 mm or less.

Incidentally, in recent years, wireless optical communication modules represented by IrDA (Infrared Data Association) and the like have been desired to be further downsized due to the downsizing and thinning of mobile phones and notebook personal computers on which these are mounted. For this reason, it is desired to reduce the size of the eye-safe laser light source itself mounted on the wireless optical communication module. On the other hand, the radiation intensity required for communication has hardly changed. Therefore, there is a strong demand for an eye-safe laser light source that is small in size and has a radiation intensity that is comparable to or higher than that of the prior art.

  For this reason, a laser light source technology has been proposed that makes laser light emitted from a semiconductor laser pass through a light scattering region, thereby increasing the diameter of the laser light source and reducing the spatial coherency of the laser light to make it eye-safe. Has been. This technique will be described below with reference to the drawings.

  FIG. 16 shows a cross-sectional view of an eye-safe laser light source according to the prior art. The eye-safe laser light source includes a glass epoxy substrate 8, and a counterbore hole 2 is formed in the glass epoxy substrate 8, and the surface of the counterbore hole 2 is for reflecting light scattered in a light scattering region 10 described later. Gold-plated. The semiconductor laser element 1 is mounted near the center of the bottom surface of the counterbored hole 2. In the counterbore hole 2, a light scattering region 10 filled with a mixture of a silicon-based resin 4 and light scattering particles 3 having a refractive index different from that of the resin is formed. A light guide 9 is formed thereon, and a part of the outer surface of the light guide 9 has a convex lens shape.

  The laser light emitted from the semiconductor laser element 1 is scattered in the light scattering region 10 and becomes an incoherent secondary surface light source (a light distribution having random directivity that cannot be collected any more). A light source having Thereby, the diameter of the apparent light source of the light emitted from the semiconductor laser element 1 is increased. The secondary surface light source obtains a lens gain (an effect of increasing the apparent light source diameter by a lens or the like) by a convex lens provided on the outer surface of the light guide unit 9, and the apparent light source diameter is further increased.

  It is known that the lens gain of the eye-safe laser light source having such a configuration depends on the refractive index of the material constituting the lens 9. For this reason, a high lens gain is obtained by using a high refractive index material for the lens 9. Can be obtained. However, since a high refractive index material is required to have high adhesion to the substrate 8 and excellent workability, there is an upper limit to the refractive index value that can be practically used. For this reason, it is difficult to obtain a high lens gain by changing the lens material, and there is a problem that the diameter of the apparent light source cannot be sufficiently increased.

  For this reason, the laser light source that satisfies the minimum radiation intensity required for the electronic equipment to be mounted and that is safe for the eyes (satisfies the maximum allowable radiation intensity) is the margin of the apparent light source diameter (allowable width of the apparent light source diameter). Becomes smaller. Therefore, there is a problem that the yield is lowered due to an increase in the number of laser light sources that do not meet the safety standards due to variations in the operating temperature and variations in the characteristics of the circuits used, semiconductor laser elements, and the like.

  On the other hand, if the thickness of the light scattering region is increased or the concentration of the light scattering particles is increased to increase the diameter of the apparent light source, the radiation intensity decreases, and the characteristics as a laser light source deteriorate. There is.

  Here, the following patent document 1 is mentioned as a technique regarding an eye safe laser.

WO03-077389

  Patent Document 1 proposes that the concentration of the light scatterer in the vicinity of the laser light source is made higher than the concentration in the external region. According to this technique, even if a high-power semiconductor light emitting device is used, it is safe for human eyes and high light extraction efficiency can be obtained.

  However, even if this technique is used, the diameter of the apparent light source cannot be sufficiently increased.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an eye-safe laser light source having a high radiation intensity and a large diameter of an independent light source, and an electronic apparatus using the eye-safe laser light source.

The basic configuration of the present invention for solving the above problems includes a semiconductor laser element, a light scattering region provided between the laser beam emitted from the semiconductor laser element and the external space, and the light scattering region. A light guide unit provided continuously on the outer space side than the first region located on the semiconductor laser element side and the outer space side. A refractive index of the first region is lower than a refractive index of the second region and higher than a refractive index of the light scattering region.
According to a first aspect of the present invention, in the basic configuration described above, at least a part of the surface of the light guide section on the outer space side has a convex lens shape, and the thickness of the second region in the optical axis direction is the thickness of the lens. The eye half laser angle of the eye-safe laser light source is ± 10 degrees to ± 40 degrees.
According to a second aspect of the present invention, in the above basic configuration, the thickness of the first region in the optical axis direction is 50 μm or more.
According to a third aspect of the present invention, in the basic configuration described above, the center of the secondary surface light source formed in the light scattering region, an arbitrary point on the boundary surface between the first region and the second region, Is monotonically increased as the distance from the optical axis to the arbitrary point increases.

  The effect of this configuration will be described with reference to FIGS. FIG. 17 is a diagram for explaining the lens gain of a conventional laser light source, and FIG. 4 is a diagram for explaining the lens gain of the laser light source according to the present invention. In the conventional light source, as shown in FIG. 17 (a), the distance H between the luminous body 20 embedded in a module having a lens with a refractive index n1 (its radial direction size is d) can be separated. When observed from the outside, the size of the illuminant appears to be 2 × r1 due to the effect of the lens.

  FIG. 17B shows a case where the refractive index n2 of the lens is larger than that shown in FIG. 17A (n2> n1). In this case, since the refraction angle of the light emitted from the light emitter is large, the size of the light emitter 20 appears to be 2 × r2 (r2> r1) when observed from the outside at the same distance H.

  The ratio r1 / d or r2 / d of the apparent size (2 × r1 or 2 × r2) of the light emitter 20 to the size (2 × d) of the original light emitter 20 is a so-called lens gain. As can be seen from this figure, the lens gain increases as the refractive index of the lens material increases.

In the configuration of the present invention, as shown in FIG. 4, the light guide 9 provided between the light emitter 20 and the external space has the first region 91 having a low refractive index on the light scattering region side. And a second region 92 having a high refractive index on the external space side. Similarly to FIG. 17A showing the lens gain of a conventional laser light source, if the refractive index of the outer lens (second region 92) is n1, it passes through the center point on a surface separated by a distance H from the lens. The light ray passes through the same trajectory (distance r1 on the lens) as the light ray shown in FIG. When this light beam is further extended in the direction of the laser element 1, the boundary surface between the first region 91 and the second region 92 is refracted toward the center of the light emitter 20 according to Snell's law, Then, it becomes the position of d ′. As can be seen from the above, the light source of FIG. 4 sacrifices the radiation intensity even when the light emitter 20 (d ′ <d) smaller than the light source of FIG. The same apparent light source diameter r1 is obtained. Conversely, if the size d of the light emitter 20 is the same, the apparent light source diameter r0 can be increased.
In addition, the same effect as that at the boundary surface between the first region 91 and the second region 92 can be obtained at the boundary surface between the light scattering region and the first region. Therefore, the diameter of the apparent light source can be further increased.

  Similarly, similarly to FIG. 17B, when the refractive index of the outer lens (second region 92) is n2, the light emitter 20 smaller than the light source of FIG. 17B is used. Also, the same apparent light source diameter can be obtained.

  In the above description, the light source including the lens is described. However, in the case of the light source not including the lens, the effect of expanding the apparent light source diameter due to the difference in refractive index can be obtained, although the effect of expanding the light source diameter by the lens cannot be obtained. Therefore, even if a lens is not provided, the apparent light source diameter can be sufficiently enlarged.

In the first aspect of the present invention, the at least part of the surface of the light guide portion on the outer space side has a convex lens shape, whereby the diameter of the apparent light source can be further increased by the lens.
Further, in the first aspect of the present invention, the optical axis direction of the thickness before Symbol second region is at least half of the thickness of the lens, ± directional half angle of the eye-safe laser light source is 10 degrees ± 40 Degree.
In order to sufficiently obtain the effects of the present invention, in the first aspect of the present invention, the thickness of the second region in the optical axis direction is set to 1/2 or more the thickness of the lens. In the first aspect of the present invention, a directivity half-value angle suitable as an eye-safe laser light source is within the above range.

In the second aspect of the present invention, in order to sufficiently obtain the effects of the present invention, in the above basic configuration, the thickness of the first region in the optical axis direction (direction A in FIG. 1) is set to 50 μm or more.

In a third aspect of the present invention, in the above basic configuration, the center of a secondary surface light source formed on the light scattering region, and an arbitrary point on the boundary surface between the first region and the second region, The distance is increased monotonously as the distance from the optical axis to the arbitrary point increases.
According to this configuration, when the light emitted from the secondary surface light source formed on the light scattering region is observed from the outside, the boundary light is largely refracted to the optical axis side, so that the diameter of the apparent light source is further expanded. it can. Here, an arbitrary point on the boundary surface between the first region and the second region is a main light beam (a light beam whose final light angle is within 60 degrees from the optical axis). Means any point in the region where

  In the above structure, both the first region and the second region can be made of a resin whose main component is the same material.

  According to this structure, since the resin which has the same system material as a main component is used, both have good adhesiveness and can prevent separation between the first region and the second region.

  As such a resin, it is preferable to use an epoxy resin that is excellent in adhesiveness with a glass epoxy suitably used as a substrate and whose refractive index can be changed by changing the resin composition.

  In the above structure, a difference in refractive index between the first region and the second region may be 0.04 or more.

  If the refractive index difference between the first region and the second region is less than 0.04, the effect of expanding the apparent light source diameter is reduced. Therefore, it is preferable to regulate as described above.

  In the above configuration, the distance between the center of the secondary surface light source formed on the light scattering region and an arbitrary point on the boundary surface between the first region and the second region is from the optical axis. As the distance to the arbitrary point increases, a monotonously increasing configuration can be employed.

  According to this configuration, when the light emitted from the secondary surface light source formed on the light scattering region is observed from the outside, it is refracted largely toward the optical axis at this boundary surface. Can be expanded. Here, an arbitrary point on the boundary surface between the first region and the second region is a main light beam (a light beam whose final light angle is within 60 degrees from the optical axis). Means any point in the region where

In the third invention, the boundary surface between the first region and the second region, can be configured to be a convex shape projecting toward the direction of the semiconductor laser element.

  According to this configuration, refraction at the boundary surface between the first region and the second region can be further increased, and the diameter of the apparent light source can be further increased.

  In the above configuration, the first region may be an epoxy resin, and the second region may be a pet (PET: polyethylene terephthalate) resin.

  According to this configuration, an epoxy resin is preferable because it has a refractive index lower than that of a pet resin, is easy to mold both materials, and is excellent in adhesion between the two materials.

A second aspect of the present invention for solving the above problems is a semiconductor laser device, a light scattering region provided between the time when laser light emitted from the semiconductor laser device reaches an external space, and the light scattering region. A light guide unit provided on the outer space side of the light source unit, wherein the light guide unit includes three or more layers having different refractive indexes, and the plurality of layers are the semiconductor toward the laser side to the outer space side, Ri configuration der that is greater sequentially refractive index, the refractive index of the plurality of layers are both characterized by a refractive index greater than the light scattering region.

  The above-described effects can be obtained in the same manner even when the light guide unit has not only a two-layer structure but also a structure in which the light guide unit has three or more layers.

  A third aspect of the present invention for solving the above problems is an electronic apparatus equipped with the eye-safe laser light source having the above-described configuration.

  As described above, according to the present invention, the diameter of the apparent light source can be increased without reducing the radiation intensity. Moreover, since the diameter of the apparent light source can be increased, the maximum allowable radiation intensity can be improved. This makes it possible to mount a light source having a small outer size on a small electronic device that requires high radiation intensity. Moreover, since the maximum allowable radiation intensity can be increased by increasing the diameter of the apparent light source, the intensity that can be emitted by a single light source can be increased. Therefore, the number of light sources required for the electronic device can be reduced, and the cost of the electronic device equipped with this light source can be reduced. Furthermore, since the margin of the apparent light source diameter is expanded, the yield can be improved and the cost can be further reduced.

(Embodiment 1)
Embodiment 1 of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view of a substrate module for optical communication equipped with an eye-safe laser light source according to the first embodiment.

  The eye-safe laser light source includes a substrate 8, and a counterbore hole 2 is formed on the upper surface of the substrate 8, and the surface of the counterbore hole 2 is subjected to a gold plating process. The semiconductor laser 1 is mounted near the center of the bottom surface of the counterbore hole 2. The semiconductor laser 1 is a normal edge emitting laser. The gold plating functions as a reflection film that reflects light scattered by a light scattering region 10 described later, and also functions as an electrode of the semiconductor laser 1.

  The semiconductor laser 1 is electrically connected to a pad 6a disposed on the substrate 8 by a metal wire 5a. The counterbore 2 is filled with a resin 4 in which light scattering particles 3 are kneaded to form a light scattering region 10. On the substrate 8 and the light scattering region 10, a low refractive index region (first region) 91 that also serves as a protective film, and a high refractive index region (second region) 92 in which the surface on the outer space side has a convex lens shape. A light guide portion 9 is formed. The radius of curvature of the lens shape may be designed in a timely manner according to the radiation angle distribution of the semiconductor laser and the concentration of light scattering particles. The refractive index of the light scattering region 10 (the refractive index of the resin 4) is smaller than that of the low refractive index region 91.

FIG. 2 shows an internal view of the optical communication substrate module according to the first embodiment (state diagram with the light guide unit 9 removed), and FIG. 3 shows an overview of the module. Although not shown in FIG. 1, an IC 7 for driving a semiconductor laser is mounted on a substrate 8 as shown in FIG. Here, because of restrictions on the height (corresponding to the x direction in FIG. 2) of the module according to the product standard, in order to reduce the height as much as possible without impairing the optical characteristics, as shown in FIG. Is a shape in which a part of the lens is cut.

  The function of the eye-safe laser light source will be described with reference to FIG. The laser light emitted from the laser is scattered by the light scattering particles 3 and travels in the counterbore 2 while changing its traveling direction. The scattered light is reflected directly or by gold plating of the counterbore hole 2 and reaches the upper surface of the light scattering region 10. The light that has reached the upper surface is sufficiently scattered, and the radiation angle distribution in the light scattering region 10 becomes a nearly perfect Lambertian distribution. Therefore, on the upper surface of the light scattering region 10, a random directional two-dimensional surface light source that cannot collect light any more is formed. This light is emitted to the external space via the light guide unit 9 including the low refractive index region 91 and the high refractive index region 92.

  The light incident on the low refractive index region 91 from the light scattering region 10 changes its traveling direction at the boundary surface between the light scattering region 10 and the low refractive index region 91 according to Snell's law. The light that has passed through the low refractive index region 91 enters the high refractive index region 92, but also changes the traveling direction in accordance with Snell's law at this boundary surface. At this time, the light rays B and C radiated at an angle with respect to the optical axis A are refracted so as to be folded back toward the optical axis A as shown in the figure and released to the external space due to the magnitude relationship of the refractive index. .

  The principle of increasing the diameter of the apparent light source will be described with reference to FIGS. FIG. 17 is a diagram for explaining the lens gain of a conventional light source, and FIG. 4 is a diagram for explaining the lens gain of the light source according to the present embodiment.

  As shown in FIG. 17 (a), the distance H is separated from the luminous body 20 (corresponding to the light scattering region 10 in FIG. 1) embedded in the module having the refractive index n1 and having a radial size d. When viewed from the outside, the size of the light emitter 20 appears to be 2 × r1.

  FIG. 17B shows a case where the refractive index n2 of the lens is larger than that shown in FIG. 17A (n2> n1). In this case, the angle of refraction of the light emitted from the light emitter 20 becomes large, and the size of the light emitter 20 appears to be 2 × r2 (r2> r1) when observed from outside the distance H. The magnification r1 / d or r2 / d with respect to the size 2 × d of the original light emitter 20 is a so-called lens gain, and the lens gain increases as the refractive index increases.

In the present embodiment, as shown in FIG. 4, the light guide 9 positioned between the light emitter 20 (corresponding to the light scattering region 10 in FIG. 1) and the external space has two refractive indexes different from each other. It consists of layers (first region 91 and second region 92). Similarly to FIG. 17A, when the refractive index of the lens (second region 92) is n1, the light ray that passes through the center point on the surface that is a distance H away from the lens is the light ray shown in FIG. And the same trajectory (distance r1 on the lens). When this light ray is further extended in the opposite direction, the boundary surface between the low refractive index region 91 and the high refractive index region 92 is refracted in accordance with Snell's law, so that the position on the light emitter 20 is d ′. From this, it can be seen that the same apparent light source diameter r1 can be obtained in the optical system of FIG. 4 even if the light emitter 20 (d ′ <d) is smaller than the optical system of FIG. Conversely, if the size d of the light emitter 20 is the same, the apparent light source diameter r0 can be increased.
The same applies when the refractive index of the second region 91 is n2.

Example 1
A substrate module for optical communication similar to that of the above embodiment was manufactured. The manufacturing method is shown below.

  A counterbore hole 2 having an upper diameter of 1.3 mm, a bottom diameter of 0.7 mm, and a depth of 0.3 mm was formed on a glass epoxy substrate 8 having a thickness of 8 mm, and the surface of the counterbore hole 2 was subjected to gold plating. The semiconductor laser 1 was mounted near the center of the bottom surface of the counterbored hole 2. The size of the semiconductor laser 1 is W 0.3 mm, D 0.5 mm, H 0.1 mm, and the oscillation wavelength is 850 nm. The semiconductor laser 1 is a normal edge emitting laser.

  Pads 6a to 6e are arranged on the substrate 8, and the pad 6a and the semiconductor laser 1 are electrically connected by a metal wire 5a. Next, a mixture of light scattering particles 3 made of acrylic resin (refractive index n = 1.50) having an average particle diameter of 2 μm in a silicon based low hardness resin 4 (refractive index n = 1.41) in a counterbore 2 And the silicon resin was thermally cured to form the light scattering region 10.

  An IC 7 for driving the semiconductor laser 1 and pads 6b to 6e are arranged on the substrate 8, and the pads 6b to 6e and IC 7 are electrically connected by metal wires 5b to 5e. Further, the IC 7 and the electrode pad 6f electrically connected to the counterbore hole 2 were electrically connected by a metal wire 5f.

  Next, from a low refractive index region (first region, refractive index n = 1.52) 91 made of an epoxy resin also serving as a component protective film, and a pet (PET: polyethylene terephthalate) based resin having a hemispherical lens shape The high-refractive index region (second region, refractive index n = 1.60) 92 to be formed was molded to produce a substrate module for optical communication according to Example 1. The low refractive index region 91 and the high refractive index region 92 serve as the light guide unit 9 that guides light to the external space. The lens has a radius of curvature of 1.2 mm in the xy direction and 1.1 mm in the z direction. The distance from the top surface of the substrate to the center of the lens was 1.0 mm.

  When the eye-safe laser light source according to Example 1 was driven using the IC 7, an apparent light source diameter of 1.49 mm was obtained for a laser current of 100 mA and an optical output of 80 mW. The pointing half-value angle was ± 25 degrees and the minimum radiation intensity was 88 mW / sr within ± 15 degrees.

(Comparative Example 1)
As shown in FIG. 16, instead of producing a protective film and a lens in a low refractive index region and a high refractive index region, the protective film and the lens are provided only with an epoxy resin (n = 1.52). A substrate module for optical communication according to Comparative Example 1 was produced in the same manner as in Example 1 except that the light guide 9 was formed.

  When the eye-safe laser light source according to Comparative Example 1 was driven using the IC 7, the apparent light source diameter was 1.30 mm for a laser current of 100 mA and an optical output of 80 mW. The pointing half-value angle was ± 26 degrees, and the minimum radiation intensity was 86 mW / sr within ± 15 degrees.

  From the above results, it can be seen that the eye-safe laser light source according to Example 1 was able to expand the apparent light source diameter by 0.19 mm compared to the eye-safe laser light source according to Comparative Example 1. This is due to the reason described above.

  In addition, since the directional half-value angle and the minimum radiant intensity were substantially the same as in Example 1 and Comparative Example 1, the adoption of the configuration of this example allowed the use of an independent light source without degrading the light source characteristics such as radiant intensity. It turns out that a diameter can be expanded effectively.

  In the first embodiment, an epoxy resin material is used as the low refractive index region 91. However, a material having a lower refractive index, such as a silicon resin, can also be used. However, when glass epoxy is used for the substrate 8, it is preferable to use an epoxy resin having excellent adhesion to the substrate 8. In the case of Example 1, in terms of the refractive index, the light scattering region 10 <the low refractive index region 91 <the high refractive index region 92.

(Comparison form)
As described in the first embodiment, the lens gain can be increased by increasing the refractive index of the resin material used for the lens. Here, as a comparative form, instead of producing a protective film and a lens in a low refractive index region and a high refractive index region, these two are made of the same resin, and the refractive index of the resin is changed variously. The eye-safe laser light source made is manufactured, and compared with the apparent light source diameter of the eye-safe laser light source according to Example 1 described above. FIG. 5 shows the result.

  As can be seen from FIG. 5, it was confirmed that the diameter of the apparent light source increased almost monotonously by increasing the refractive index of the resin used for the lens. However, as shown in FIG. 5, when the resin having the same refractive index as that of the high refractive index region used in Example 1 is used, the apparent light source diameter is smaller than that in Example 1. This is due to the reason described with reference to FIGS. As the lens resin material, an epoxy resin was used as a material having a refractive index of less than 1.6, and a pet resin was used as a material having a refractive index of more than that.

(Embodiment 2)
FIG. 6 shows an eye-safe laser light source according to the second embodiment. From the consideration using FIG. 4, it is conceivable that the effect of expanding the diameter of the apparent light source increases as the thickness of the low refractive index region 91 increases. However, when the boundary surface between the low refractive index region 91 and the high refractive index region 92 is at the lens tip portion, there arises a problem that the amount of light passing through the portion decreases.

  Here, in the present embodiment, the effect of expanding the apparent light source diameter when the boundary surface between the low refractive index region 91 and the high refractive index region 92 is moved toward the lens tip is studied. Here, the distance from the center of the lens (D1 / H1, H1 = 1.1 mm) was used as a parameter, and the change in the apparent light source diameter expansion effect was observed while changing the refractive index of the high refractive index region 92. All other structures are the same as those in the first embodiment.

  Here, the refractive index of the low refractive index region 91 was individually optimized so that the apparent light source diameter could be expanded most under the condition of 1.52 or more. As a result of producing various light sources, it was confirmed that the apparent light source diameter can be expanded most when the refractive index is 1.52 as the low refractive index region.

  Further, it was confirmed that when D1 / H1 exceeds 0.5, the effect of expanding the apparent light source cannot be expected with any refractive index resin. This is presumably because if the boundary surface between the low-refractive index region 91 and the high-refractive index region 92 is at the tip of the lens, the amount of light passing through that portion is reduced.

  FIG. 7 shows a ternary relationship between D1 / H1, the value of the refractive index of the high refractive index region, and the diameter of the apparent light source using a resin having a refractive index of 1.52 as the low refractive index region. The vertical axis is the difference from Comparative Example 1, and a positive value indicates that there is an effect of expanding the apparent light source diameter.

  As can be seen from FIG. 7, when the boundary surface is in the condition of the interface 4 (D1 / H1 = 0.5), there is almost no effect of increasing the light source diameter regardless of the refractive index resin used. On the other hand, when the boundary surface is in the condition of the interface 1 (D1 / H1 = 0.125), it can be seen that there is an effect of expanding the light source diameter regardless of the resin having any refractive index as the high refractive index region 92. .

  In addition, when the refractive index difference between the low refractive index region 91 and the high refractive index region 92 is less than 0.04 (the refractive index of the high refractive index region is less than 1.56), the effect is obtained regardless of the position of the boundary surface. Is small. It can also be seen that when the refractive index difference is 0.08 or more and D1 / H1 <0.5, the effect of expanding the apparent light source diameter is large. Therefore, the refractive index difference between the low refractive index region 91 and the high refractive index region 92 is preferably 0.04 or more, and more preferably 0.08 or more.

  The range of D1 / H1 having the effect of expanding the diameter of the apparent light source is considered to vary depending on the size of the light source module and the lens design guidelines, but D1 / H1 is less than 0.5 at the directivity half-value angle of ± 10 degrees to 40 degrees. It was confirmed that the range was effective. This is probably because the optimum lens shape is substantially fixed for each directional half-value angle, and the difference in the size of the light source module can be dealt with by increasing or decreasing the lens size.

(Embodiment 3)
In the third embodiment, the relationship between the thickness of the low refractive index region 91 and the effect of expanding the diameter of the apparent light source is considered. As shown in FIG. 8, the result when the boundary surface between the low refractive index region 91 and the high refractive index region 92 is moved from the lens center to the secondary surface light source, that is, toward the substrate 8 is shown in FIG. . The distance between the substrate and the lens center was 1.0 mm.

  From FIG. 9, it can be seen that the closer the boundary surface between the low refractive index region 91 and the high refractive index region 92 is to the lens center (the smaller D2 / H2 is), the more effective. However, it can be seen that even if D2 / H2 = 0.95, the diameter of the apparent light source can be sufficiently increased. At this time, the actual thickness of the low refractive index region 91 is 50 μm.

(Embodiment 4)
In the fourth embodiment, the boundary surface shape that further exhibits the effect of expanding the apparent light source diameter is examined. As shown in FIG. 10, the boundary surface between the low refractive index region 91 and the high refractive index region 92 has a concave shape protruding toward the semiconductor laser element side.

  What is necessary is just to design an actual concave shape timely according to the resin material to be used and the target apparent light source diameter. This embodiment is characterized in that the distance from the secondary surface light source to the boundary surface between the low refractive index region 91 and the high refractive index region 92 increases as the distance from the optical axis increases. In this embodiment, when the light beam observed from the outside extends to the light scattering region side, it is largely refracted inward (on the optical axis side) at the boundary surface between the first region 91 and the second region 92. Has the effect of increasing

  The influence on the radiation intensity-angle pattern related to all of the first to fourth embodiments will be examined. When laser light that has spread widely inside the resin is emitted into space like an eye-safe laser light source, it is difficult to control the radiation intensity-angle distribution. In particular, since the light condensing performance is deteriorated, it is difficult to concentrate the light amount in a narrow angle range. Even in such a case, the higher the refractive index of the lens material, the more light is refracted, and thus the light condensing property can be improved.

  The dotted line in FIG. 11 represents the minimum radiant intensity within a cone of ± 15 degrees when the single resin material produced in Comparative Example 1 is used and the refractive index is changed variously. In FIG. 11, for the eye-safe laser light source manufactured under the condition of the interface 5 in the third embodiment, the radiation intensity is measured by changing the refractive index of the resin material in the high refractive index region 92. As can be seen from the dotted line in FIG. 11, as the refractive index of the resin increases, the light condensing property tends to improve and the minimum radiation intensity tends to increase. However, if the refractive index of the resin becomes larger than 1.62, Since it deviates from the lens shape value suitable for the rate, a convex curve is drawn upward. Moreover, it turns out that the same tendency is seen also in this Embodiment.

  From this, the low refractive index region 91 is considered to be determined by the refractive index of the high refractive index region 92 without significantly affecting the radiation intensity. Therefore, by introducing the low refractive index region 91, it is possible to increase the size of the apparent light source without affecting the radiation intensity.

  In the eye-safe laser light source used in the above embodiment, the high refractive index region 92 is formed of a resin material, but it may be a glass material having a higher refractive index. In particular, if the mold glass is mold glass, the above-described production method can be used as it is, so that a light source can be produced at low cost.

(Embodiment 5)
In Embodiment 5, an illumination device using a blue semiconductor laser (wavelength 400 nm band) will be described. FIG. 12 shows an illumination device using a blue semiconductor laser element. FIG. 14B is a schematic view of the substrate, and FIG. 14A is a detailed view of the light source unit.

  As shown in FIG. 14, the counterbore 2 provided in the substrate 8 and the semiconductor laser element 1 disposed therein are surrounded by the light scattering particles 3 and the resin 4 as in the first embodiment. It is.

  As shown in FIG. 12, the substrate is molded with a low refractive index region 91 including the phosphor 11 and further molded with a high refractive index region 92 including the phosphor 11. The low refractive index region 91 and the high refractive index region 92 are formed with the same thickness.

  The phosphor 11 is made of, for example, indium nitride (InN) compound semiconductor particles, and the sizes thereof are about 5 nm, 6 nm, and 13 nm. These phosphors 11 are excited by light having a wavelength of 400 nm and emit blue, green and red fluorescence, respectively. As a result, these colors are mixed and can be used as a white lighting device. In addition, since this fluorescent substance is small enough with respect to a wavelength, light is not scattered by fluorescent substance.

  Light scattering occurs in a light scattering region where the light scattering particles 3 exist, and a secondary surface light source is formed in this region, and the laser light is emitted to the external space through the light guide unit 9. Here, although the high refractive index region 92 does not have a lens shape, it has a large lens gain due to a refractive index difference from air, and the final apparent light source diameter is determined. Since the lens curved surface is not formed, there is no restriction on the thickness of the high refractive index region 92 as described in the second embodiment. As in the first embodiment, the lens gain is larger than the case where a single material is used as the light guide unit 9 instead of the two-layer structure of the low refractive index region 91 and the high refractive index region 92.

  As in the present embodiment, in a lighting device or the like that does not require a sharp directivity angle, a planar shape having no lens shape can be applied. In this embodiment, since the diameter of the apparent light source can be easily increased, the illumination device itself can be designed to be thin, and the intensity and brightness of the illumination device can be achieved even when the number of semiconductor lasers is the same. Can be suppressed, and the lighting device can be enlarged.

  Such a thin and large-sized lighting device can be used as a backlight of a liquid crystal display, for example. By using this illuminating device, it is possible to realize a thinner backlight than the conventional fluorescent lamp, and it is possible to realize a beautiful screen without uneven brightness as described above. In addition, compared with a backlight using a light emitting diode that has been realized in recent years, the backlight light source (illumination device) has a small amount of decrease in light intensity over a certain period of use and excellent long-term reliability.

  From the viewpoint of weather resistance and reliability of the lighting device, it is preferable that the material of the low refractive index region 91 and the material of the high refractive index region 92 are made of the same material system resin in order to make it difficult for the materials to peel off. In the present embodiment, for example, both resin materials are made of an epoxy resin, and by adjusting the composition, the low refractive index region 91 has a refractive index of 1.52, and the high refractive index region 92 has a refractive index of 1.56. Can be set.

(Embodiment 6)
The sixth embodiment is an illumination apparatus and optical communication apparatus in the illumination apparatus according to the fifth embodiment, in which a signal is modulated and superimposed on a current applied to each laser.

  FIG. 14 shows an example of a lighting device / optical communication device. A modulated visible light signal is distributed to the entire room from the light transmissive housing 12 in which the lighting device of FIG. 12 is stored. In the case of visible light, the radiation intensity that can be radiated into the space can be made larger than that in the case of infrared light, and the communicable distance is extended. Further, when used in a room where only illumination light exists, it is possible to control background light that affects reception characteristics, and further improve reception sensitivity. In addition, the semiconductor laser is superior in modulation characteristics compared to the case where a light emitting diode is used, and is advantageous in terms of communication speed.

  As described above, the eye-safe laser light source according to the present invention can increase the diameter of the apparent light source without causing a decrease in the radiation intensity. It can be mounted on electronic devices. In addition, the light source can be miniaturized and can be mounted on a small optical wireless communication device or the like. Therefore, optical communication can be performed at a higher speed than when a light emitting diode is used.

  It can also be used as a surface light source with reduced luminance unevenness, and can be applied to lighting equipment and the like. Therefore, the industrial significance is great.

FIG. 1 is a schematic cross-sectional view of the optical module according to the first embodiment. FIG. 2 is an internal view of the optical module according to the first embodiment. FIG. 3 is an external view of the optical module according to the first embodiment. FIG. 4 is a schematic cross-sectional view illustrating the lens gain of the laser light source according to the first embodiment. FIG. 5 is a graph showing the relationship between the apparent light source diameter of the laser light source according to Example 1, the refractive index of the light guide portion of the laser light source according to the comparative example, and the apparent light source diameter. FIG. 6 is a cross-sectional view of the optical module according to the second embodiment. FIG. 7 is a graph showing the relationship between the apparent light source diameter of the optical module according to the second embodiment and the apparent light source diameter according to Comparative Example 1. FIG. 8 is a sectional view of the optical module according to the third embodiment. FIG. 9 is a graph showing the relationship between the apparent light source diameter of the optical module according to the third embodiment and the apparent light source diameter according to Comparative Example 1. FIG. 10 is a cross-sectional view of the optical module according to the fourth embodiment. FIG. 11 is a graph showing the correlation between the minimum radiation intensity and the refractive index in the high refractive index region. FIG. 12 is a schematic diagram of an optical module according to the fifth embodiment. FIG. 13 is a schematic diagram of an optical module substrate according to the fifth embodiment. FIG. 14 is a schematic diagram illustrating a lighting device with a communication function according to the sixth embodiment. FIG. 15 is a graph showing the relationship between the diameter of the apparent light source and the allowable maximum radiation intensity. FIG. 16 is a schematic cross-sectional view showing a conventional eye-safe laser light source. 17A and 17B are schematic cross-sectional views for explaining the lens gain of a conventional laser light source. FIG. 17A shows a low refractive index and FIG. 17B shows a high refractive index.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Semiconductor laser element 2 ... Counterbore hole (metal reflective surface)
3 ... Light scattering particles 4 ... Silicon-based low hardness resin 5 ... Wire 6 ... Electrode pad 7 ... IC
8 ... Substrate 9 ... Light guide 91 ... Low refractive index region (first region)
92... High refractive index region (second region)
DESCRIPTION OF SYMBOLS 10 ... Light-scattering area | region 11 ... Phosphor 12 ... Illuminator case 20 ... Luminescent body

Claims (12)

A semiconductor laser element;
A light scattering region provided between the time when the laser light emitted from the semiconductor laser element reaches the external space;
A light guide unit continuously provided on the outer space side of the light scattering region;
A light source device comprising:
The light guide section includes a first region located on the semiconductor laser element side and a second region located on the external space side,
The refractive index of the first region is lower than the refractive index of said second region, rather, high than the refractive index of the light scattering region,
At least a part of the external space side surface of the light guide part has a convex lens shape,
The thickness of the second region in the optical axis direction is 1/2 or more of the thickness of the lens,
The half-value angle of the eye-safe laser light source is ± 10 degrees to ± 40 degrees,
An eye-safe laser light source. A semiconductor laser element;
A light scattering region provided between the time when the laser light emitted from the semiconductor laser element reaches the external space;
A light guide unit continuously provided on the outer space side of the light scattering region;
A light source device comprising:
The light guide section includes a first region located on the semiconductor laser element side and a second region located on the external space side,
The refractive index of the first region is lower than the refractive index of the second region and higher than the refractive index of the light scattering region;
The thickness in the optical axis direction of the first region is 50 μm or more.
An eye-safe laser light source. A semiconductor laser element;
A light scattering region provided between the time when the laser light emitted from the semiconductor laser element reaches the external space;
A light guide unit continuously provided on the outer space side of the light scattering region;
A light source device comprising:
The light guide section includes a first region located on the semiconductor laser element side and a second region located on the external space side,
The refractive index of the first region is lower than the refractive index of the second region and higher than the refractive index of the light scattering region;
The distance between the center of the secondary surface light source formed in the light scattering region and an arbitrary point on the boundary surface between the first region and the second region is from the optical axis to the arbitrary point. As the distance increases, it increases monotonously.
An eye-safe laser light source. The boundary surface between the first region and the second region is a convex shape protruding toward the direction of the semiconductor laser element,
The eye-safe laser light source according to claim 3 . Both the first region and the second region are made of a resin whose main component is the same material,
The eye-safe laser light source according to any one of claims 1 to 4, wherein the eye-safe laser light source is provided. The resin is an epoxy resin,
The eye-safe laser light source according to claim 5. The refractive index difference between the first region and the second region is 0.04 or more.
Eye-safe laser source according to any one of claims 1 to 6, characterized in that.   The eye-safe laser light source according to any one of claims 1 to 4, wherein the first region is an epoxy resin and the second region is a pet resin. A semiconductor laser element;
A light scattering region provided between the time when the laser light emitted from the semiconductor laser element reaches the external space;
A light guide unit continuously provided on the outer space side of the light scattering region;
A light source device comprising:
The light guide part is composed of a plurality of layers having three or more different refractive indexes,
The plurality of layers are configured such that the refractive index increases sequentially from the semiconductor laser element side toward the external space side,
The refractive indexes of the plurality of layers are all greater than the refractive index of the light scattering region,
At least a part of the external space side surface of the light guide part has a convex lens shape,
Of the layers constituting the light guide part, the thickness in the optical axis direction of the layer farthest from the light scattering region is ½ or more of the thickness of the lens,
The half-value angle of the eye-safe laser light source is ± 10 degrees to ± 40 degrees,
An eye-safe laser light source.   A semiconductor laser element;
A light scattering region provided between the time when the laser light emitted from the semiconductor laser element reaches the external space;
A light guide unit continuously provided on the outer space side of the light scattering region;
A light source device comprising:
The light guide part is composed of a plurality of layers having three or more different refractive indexes,
The plurality of layers are configured such that the refractive index increases sequentially from the semiconductor laser element side toward the external space side,
The refractive indexes of the plurality of layers are all greater than the refractive index of the light scattering region,
Of the layers constituting the light guide part, the thickness of the layer in contact with the light scattering region in the optical axis direction is 50 μm or more.
An eye-safe laser light source. A semiconductor laser element;
A light scattering region provided between the time when the laser light emitted from the semiconductor laser element reaches the external space;
A light guide unit continuously provided on the outer space side of the light scattering region;
A light source device comprising:
The light guide part is composed of a plurality of layers having three or more different refractive indexes,
The plurality of layers are configured such that the refractive index increases sequentially from the semiconductor laser element side toward the external space side,
The refractive index of the plurality of layers are both rather greater than the refractive index of the light scattering region,
A boundary surface between the center of the secondary surface light source formed in the light scattering region and a layer in contact with the light scattering region and a layer in contact with the light scattering region among the layers constituting the light guide unit The distance from an arbitrary point in increases monotonously as the distance from the optical axis to the arbitrary point increases.
An eye-safe laser light source. An electronic device equipped with the eye-safe laser light source according to any one of claims 1 to 4 .

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