JPS6343727B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an optical control device used as an optical carrier that has active functions such as optical modulation and optical branching.

Prior Art Conventionally, in order to modulate or branch light propagating in an optical fiber, a device that appropriately controls the light using mechanical means, electro-optic effect, or acousto-optic effect is connected to the optical fiber via an optical waveguide. I am trying to install it on. FIG. 4 shows an example of this, in which the input side optical fiber 13 and the output side optical fiber 1 are connected.
A thin film optical waveguide 15 is connected between the thin film waveguide 15 and the thin film waveguide 15, and the refractive index of this thin film waveguide 15 is appropriately changed at that portion by a control device 16 to confine and guide light.

However, in such conventional optical control devices, a method for directly and efficiently coupling an optical fiber and an optical waveguide has not yet been established.
A dedicated coupler with high optical coupling efficiency is required,
The entire device must be sophisticated and complicated. In addition, the thickness of the thin film optical waveguide is several μm.
However, the requirements for alignment for optical coupling and the flatness of the end face of the optical fiber are extremely strict, and various problems remain in practical use.

OBJECTIVES Therefore, an object of the present invention is to provide an optical control device that eliminates the above-mentioned disadvantages by giving an active function to the optical fiber itself, which conventionally only played the role of propagating light.

Configuration To achieve this object, the present invention provides an optical directional branch path formed by coupling a first optical fiber and a second optical fiber;
an ultrasonic transducer disposed on an end face of a third optical fiber coupled to the optical directional branch so that the ultrasonic wave propagates substantially parallel to the propagation direction of the light wave input into the optical fiber; and selectively transmitting the light wave input into the first optical fiber and reflected by the ultrasound propagation to the second optical fiber via the optical directional branch path according to the ultrasound signal. It is configured to branch.

Since the optical fiber has a fine structure, the excitation power of the ultrasonic wave is extremely small, and the above-mentioned problems in input/output coupling of the optical fiber can be essentially solved.

The invention will now be explained in further detail with reference to embodiments shown in the drawings.

According to the present invention, first, as shown in FIG. 1, a thin piezoelectric material film 3 is formed on the end face of the optical fiber 1 so that ultrasonic waves propagate substantially parallel to the propagation direction of the light waves propagating in the optical fiber 1. An ultrasonic transducer 2 is formed in which the electrode thin films 4 and 5 sandwich the ultrasonic transducer 2 between the electrode thin films 4 and 5. As the piezoelectric material thin film 3, ZnO thin film,
A LiNbO ₃ crystal thin piece or the like can be used.
ZnO thin films can be formed into high-quality thin films for transducers by sputtering. The materials of the electrode thin films 4 and 5 include Au, Al, and In.
Metals such as are used. Further, as the optical fiber 1, one having a core diameter of 10 to 150 microns is usually used. An excitation voltage is applied between the electrode thin films 4 and 5 from an ultrasonic generation power source 6.

Next, using the optical fiber 1 having the transducer 2 shown in FIG. 1, as shown in FIG. A light control device is configured in which a first optical fiber 7 and a second optical fiber 9 are branched via a branching path 8 .

In the optical control device according to the present invention configured in this manner, when the power source 6 is applied to the transducer 2, ultrasonic waves are excited in the portion 10 of the third optical fiber 17 that is close to the transducer 2. At this time, when a light wave P is made incident from the opposite end of the first optical fiber 7, the light wave is diffracted by ultrasonic waves at the ultrasonic excitation portion 10 in the third optical fiber 17 via the optical directional branch path 8. reflected. At that time, not all of the arriving light waves are diffracted and reflected, but the frequency that satisfies the relationship 2k = mK, where k is the wave number vector of the light wave, that is, the propagation constant, K is the wave number vector of the ultrasonic wave, and m is an integer. Only light waves are diffracted and reflected. The diffracted and reflected light wave is transmitted to the optical directional branch path 8.
The light hardly enters the first optical fiber 7, but enters the second optical fiber 9, and is output as an output light wave Q from its output end.

In this way, the device shown in FIG. 2 can propagate light from the first optical fiber 7 to the second optical fiber 9 only when there is an ultrasonic signal, and the output light intensity is also the same as the ultrasonic output. It can be controlled by the amplitude of the grating created by the sound waves.

Note that the ultrasonic output can be controlled by an external electrical signal using the configuration shown in FIG.
In FIG. 3, reference numeral 11 is a transmission signal generator provided as an external electric signal source, and the output signal thereof modulates the ultrasonic signal from the ultrasonic generation power source 6 in the mixer 12, and the output is amplified in the amplifier 13. is applied to the transducer 2.

Effects As described above, according to the present invention, the ultrasonic excitation part excited in the third optical fiber by the ultrasonic transducer reflects the incident light wave from the first optical fiber, and converts it into light. Since the output is made to the second optical fiber side via a directional branch path, the efficiency of optical coupling is high, unlike the conventional method using an optical coupler, and the optical arrangement is Problems such as complexity and poor workability can essentially be avoided.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of the ultrasonic conversion transducer section of the optical control device according to the present invention, FIG. 2 is a layout diagram showing an example of the overall configuration of the optical control device, and FIG.
This figure is a layout diagram showing an example of a configuration for controlling ultrasonic output by an external electric signal, and FIG. 4 is a simplified configuration diagram showing a conventional optical control device. 1, 7, 9... Optical fiber, 2... Ultrasonic transducer, 3... Piezoelectric material thin film, 4, 5...
Electrode thin film, 6... Power supply for generating ultrasonic waves, 8... Optical directional branch path, 11... Transmission signal generator, 12...
mixer.

Claims (1)

[Claims] 1 An optical directional branch path formed by coupling a first optical fiber and a second optical fiber, and an optical directional branch path substantially parallel to the propagation direction of the light wave input into the first optical fiber. an ultrasonic transducer disposed on an end face of a third optical fiber coupled to the optically directional branch such that ultrasonic waves are transmitted into the first optical fiber; An optical control device characterized in that a light wave reflected by acoustic wave propagation is selectively branched to the second optical fiber via the optical directional branch path according to an ultrasonic signal.