JPS606298B2 - optical fiber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides LO. The present invention relates to an optical fiber having a transmission window that has a transmittance over a wide wavelength range of 5 to 10 wavelengths, and has a small optical loss value particularly in a range of 2 to 7 wavelengths.

Since conventional optical fibers have Si02 as their main component,
There is infrared absorption due to the vibration of the Si-◯ bond, and optical loss is reduced only in the wavelength region of 0.6 to 1.7 degrees.

In order to obtain an optical fiber with low loss at long wavelengths exceeding this wavelength range, for example 2 to 7 wavelengths, the optical fiber is manufactured using a material whose infrared absorption edge is located on the longer wavelength side than Si02. There is a need to. As this type of infrared transmitting material, so far we have used glass mainly composed of halides, halide crystals such as KRS-5, KCI, and A-1, As
Chalcogenide glasses such as 2S3 are known, but each material has the following drawbacks, so it is impossible to create an optical fiber with small optical loss values in the wavelength range 2 to 7 deviations. There wasn't. The reason for this is that for glasses whose main components are halides, the contained components Shigeru F2, ZnC! B2 itself is unsuitable as a material for general-purpose optical fibers due to its deliquescent nature and toxicity;
This is because if eF2 and ZnC12 are excluded, it is difficult to obtain a glass state, making it difficult to produce a glass fiber.

In addition, crystal fibers using AgCI etc. cannot avoid light scattering at crystal grain boundaries, making it difficult to reduce optical loss. Furthermore, regarding chalcogenide glass, A
Although only an optical fiber using SBU3 glass has been realized, the optical loss value of this optical fiber using fake 2S3 glass is as large as 2 × 1 pi dB/fri at a wavelength of 5.5 peaks. Furthermore, since it contains highly toxic As, there is also a problem from the point of view of work safety. Chalcogenide glasses that do not contain glass, such as P-S glass, are also known, but this type of glass Very little research has been done to realize optical fibers using this material, and only some research has been done on its properties as an infrared transmitting glass (thickness is on the order of ribs to nodes).

The present invention was made in view of the current situation, and
We clarified the optimal glass composition for obtaining optical fibers using Q-P-S glass, and found that it has low toxicity and 0.5
The object of the present invention is to provide a chalcogenide glass optical fiber that has transparency over a wide range of wavelengths ranging from 10 to 10 cm, and in particular has a window of transmission over 2 to 7 wavelengths.

The details of the present invention will be explained according to the examples shown below.

Example 1 First, various two-component CeSx (x=2 to 6) glass fibers were produced according to the following procedure.

99.999% pure sulfur (S) and 99.9999
9999% germanium (W) was weighed at a predetermined ratio, and Q and S having a total weight of about 50 mm were vacuum-sealed into a quartz glass tube with a wall thickness of 3 willows and an inner diameter of 3 mm, and a length of 50 mm. S in the jurisdiction, worshiping the snake, temperature 800-10
A glass block was obtained by heating at 0,000 for 20-20 hours and then cooling. in particular"
To obtain glass using Snake S2 with Q = 33.3 mol% and S = 66.7 mol%, heating was required for ~ 20 days at loooqo.

When Snake S6 containing Q: 14.3 mol % to S: 85.7 mol % was used, sufficient vitrification was achieved by heating at 800 mol % for 20 hours. Also, the S content is 66.7 mol% and 85
．． W in the region between 7 mol% ~ i.e. x between 2 and 6
To obtain glass using SX, the heating temperature and heating time are both 800 to 1000 qC and 2
It was within the range of 0 to 20 leg hours. In this way, the heating temperature and heating time required for vitrification depend on the S content.It has been found that the higher the sulfur S content, the lower the heating temperature and the shorter the heating time, the more uniform and transparent glass can be obtained. did. Furthermore, when using QSx in the region of S < 66.?mol%, that is, x < 2, "it is not possible to obtain a uniform and transparent glass sample even if it is heated at 1000o○ for 20 periods and then air cooled." The glass thus obtained was cut and polished to obtain a glass rod with a diameter of 5 to 8 mm and a length of 30 to 5 mm. I got an unclad fiber with thick skin.

In the illustration, the code group is chalcogenide glass rod, 2 is heating element, inert gas inlet port, W rod support tube, 5 gas outlet port, flea shirt, 7 is drive motor for wire drawing, 8 1 shows the quartz glass tube for the cover.When converting to fiber, inert gas inlet 3
Inert gas is supplied into the rod support tube from the heating element 2.
The glass rod 1 is drawn at a temperature of 400 to 700 qo.
The wire was drawn at a drawing speed of 6 to 15 minutes while heating at . Here, ``In order to obtain an optical fiber with a diameter of 150 rm using WS6 glass with S = 66.7 mol%, the temperature is approximately 700 o 0, and in the case of WS6 glass with S = 85.7 mol %, the temperature is approximately 400 oo. It was possible to draw the wire.In other words, the appropriate drawing temperature is 400 to 700 qo.
Here, the higher the sulfur S content, the lower the temperature for drawing. On the other hand, as mentioned above, since fiberization is carried out under normal pressure while flowing an inert gas, sulfur S volatilizes from the glass surface during the fiberization process.

This becomes more remarkable as the sulfur S content increases, and S
Z85. In a glass with a composition of 7 mol% or xZ6,
During the drawing process, the sulfur S volatilized violently, causing the fiber surface to turn white, making it difficult to form the fiber itself.

In addition, ``When such volatilization of sulfur S occurs, the scattering loss of the obtained fiber increases, making it difficult to obtain a fiber with low optical loss. In order to obtain a low-loss optical fiber using a two-component material consisting of sulfur S, snake = 167 ~
33.3 mol%, S: 66.7-83.

It has been found that it is sufficient to use a material in the range of 3 mol %, that is, Sx (2 mm ≦5).

Next, the light transmission characteristics of the GSX (2Sx≦5) glass and the optical loss of the optical fiber using the S395 glass were measured.

(Measurement of optical loss) The optical loss of the WS3,5 (S = 77.8 mol%) glass fiber with a length of 1 to 2 mm, prepared as in Example 1 above, was measured at the wavelength of 1 to 5 # skin. Measured in the area.

The results are shown in Fig. When measuring optical loss
Using lnSb as a detector and a nichrome wire with a tungsten lamp as a light source, the fiber was cut every 30 skins and the output of each wavelength at each output end was measured, and the optical loss was determined from the output difference. In the figure, the optical loss value near wavelength 4.5 was 2.5×1 pidB'.
The absorption peak near 2.5 m is attributed to absorption by OH impurities, and the absorption peak of 3 to 4 A skin is attributed to absorption by SH impurities ~ By removing these impurities, WS
The optical loss of an optical fiber made of X-based glass can be calculated from the inherent loss of the material (
It was found that it is possible to reduce the noise level to 5 × 10-2 dB'.

(Measurement of light transmission characteristics) WS2 (S=
(66.7 mol%) The light transmission properties of the glass plate were measured over a wavelength range of 0.25 to 30 French.

The results are shown in FIG. In Fig. 3, the absorption edges of this glass are at about 0.4 F in the ultraviolet and about 12 F in the infrared, but as can be seen from Fig. 5×10-2d at wavelength castle of 7〃
It shows the low loss value of B' product. This low loss value corresponds to about the lowest loss value of silica glass fiber, which is currently widely known as glass fiber. Furthermore, the WSX ((2≦x≦5) glass used in the optical fiber of the present invention exhibits almost the same light transmission characteristics as the above-mentioned ○eS2 (S=66.7 mol%) glass, and has a 2 to 7 r It was found that there is a possibility of achieving a low loss value of less than that of a single ship at a wavelength castle of Glasses and glass fibers of various compositions were produced, and the optimal glass composition range for glass fiber production was clarified.

Snake S2P, /3 (Q = 30
mol%, S=60 mol%, P=10 mol%), heating at 950 qo for 80 hours was sufficient for vitrification.

It was found that when 10 mol% or less of phosphorus P was added, vitrification was easily performed.

However, when the phosphorus P content exceeds the proportion of phosphorus P in QS2P, that is, >25 mol%, it becomes impossible to obtain a uniform and transparent glass.On the other hand, when forming a fiber from the Q1P-S system, It has been found that when the neighboring P content is increased to 11 mol% or more, the volatilization of sulfur S and phosphorus P from the surface increases, making it impossible to obtain a fiber with low loss.

Similarly, glasses and fibers were prepared with various blending ratios of Q, P, and S. It has been found that it is possible to produce an optical fiber with a low loss of about 2×1 dB' or less only at the compounding ratio, that is, the compounding ratio within the shaded area in FIG.

Next, the optical loss of this kind of Pe-P-S glass fiber was measured.

(Measurement of optical loss) QS2.5P, /3 (Q226.

1 mol %, S 65.2 mol %, P = 8.7 mol %) An example in which the optical loss of a glass fiber was measured at a wavelength range of approximately 1 to 5 μm is shown in FIG.

In Figure 6, in the vicinity of wavelength 2 Buddha, 4
A low loss value of 4×l pi dB′ was obtained near the 4.5 mountain surface. In this manner, it has been found that with the Q-P-S glass fiber, by using glass within an appropriate composition range, a relatively low cost value can be obtained in the 2-7 slope zone.
Example 3 Next, the refractive index of the glass in the glass composition region suitable for producing the optical fiber shown in FIG. 5 was measured, and it was found that sulfur S
and increased as the phosphorus P content increased.

Therefore, by using the so-called rod-in-tube method, blocks of S3P, /3 glass and WS3 glass, which has a lower refractive index than this glass, are processed into cylindrical and cylindrical rods, respectively, and these are used as the core and cladding.
An optical fiber with a step-like refractive index distribution was drawn. The coefficients of thermal expansion of the two types of glasses used for the core and cladding are both 20 to 25 x 10-6, and the thermal matching is good.
It was possible to draw dozens of lines through the optical fiber of Buddha's skin at a speed of about low per minute. It has also been found that a relatively easy-to-handle large-diameter stepped-index optical fiber can be produced with a core made of Bo-P-S glass and a cladding made of Q-S glass. As explained above, the Snake-S type or Snake-P-S type lucogenide glass according to the present invention has low toxicity and has a glass composition of 15 to 33.3 mol%.
By setting the P content to 0 to 10 mol% and the S content to 60 to 83.3 mol%, chalcogenide glass can be easily vitrified and made into a fiber, and light with reduced optical transmission loss at a wavelength range of 2 to 7 r. fiber can be realized.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a drawing apparatus for producing the optical fiber of the present invention, and Fig. 2 shows a WS3 in the wavelength range of 1 to 5 μm.
．． 5 Optical loss characteristic curve diagram of glass fiber, Figure 3 is WS
2 A diagram of the light transmission characteristic curve for each wavelength of the glass plate (0.5 side thickness) "Figure 4 is a characteristic curve diagram showing the straight lines of the ultraviolet and infrared absorption edges, and Figure 5 is the characteristic curve diagram that is optimal for making optical fibers. Diagram L showing the glass composition range Figure 6 is an optical loss characteristic curve diagram of the WS2.5P,'3 glass fiber in the wavelength range 1 to 5#. body,
3...Inert gas inlet, 4... Core support pipe 5...
...Gas exhaust port 6...Shirt cover, 7...Driving motor for wire drawing, 8...Quartz glass tube for cover.

Claims (1)

[Claims] 1 Germanium 15-33.3 mol%, phosphorus 0-1
An optical fiber characterized in that its core or cladding is formed of glass containing 0 mol% and 60 to 83.3 mol% of sulfur.