JPH1084320A - Optical beam transmitter-receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical axis adjustment device over a wide range with a small and simple configuration and high precision by using elastically a fiber container part with an elastic hinge and directly controlling a position of an optical fiber based on a piezoelectric element and a drive signal. SOLUTION: An elastic hinge 12 is made of a metal and constricted toward a center 20 and rigidity in the axial direction is high and rigidity in the radial direction is low. A rod 11 containing an optical fiber 10 to receive an optical beam is fitted to a center of a disk at one end of the elastic hinge 12, four piezoelectric elements 13 are arranged at an equal interval to an outer ridge of the disk via four hinges 14a, 14b each in total and fixed to a case upper cover 15b. A disk at the other end of the elastic hinge 12 is pressed to a lower cover 15c of the case 15. Thus, two sets of the four piezoelectric elements 13 are differentially driven to displace the position of the optical fiber 10 in two orthogonal axial directions. A pre-load is applied to each piezoelectric element 13 so as to eliminate a hysteresis in the displacement/drive voltage characteristic thereby attaining high precision. Error detecting very small vibration and optical axis displacement control are conducted by the synthesis of command voltages and the entire configuration is made simple and small in size.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light beam transmitting / receiving apparatus used for optical communication equipment and the like.

[0002]

2. Description of the Related Art Conventionally, in an optical communication device, for example, an optical communication device between artificial satellites, a light beam transmitting / receiving device as shown in FIG. 5 has been studied. In this light beam transmitting and receiving apparatus, the communication light beam 51 is formed by using an optical axis adjustment mechanism (not shown).
The light is incident on a vibrating mirror 52 that is vibrating minutely, reflected by the vibrating mirror 52, and sent to an optical fiber (not shown) via an optical axis adjusting mirror driving mechanism 53.

A light beam 51 incident on an optical fiber via an optical axis adjusting mirror driving mechanism 53 is sent to a light detecting means 57. Then, the light beam 51 vibrating minutely is split into two light paths by the beam splitter 57a of the light detecting means 57. The separated light is supplied to the photoelectric converter 57b.
After being converted into electric signals by ₁ and 57b ₂ respectively, they are sent to an adder 57c and added.

The output of the adder 57c is a communication signal. Then, an optical axis error of the light beam 51 is obtained by the control means 56 based on the outputs of the photoelectric converters 57b ₁ and 57b ₂ and the vibration information of the vibration mirror 52, and the light beam error is obtained based on the obtained optical axis error. A control signal is output from the control means 56 such that the light is coupled to the optical fiber.
This control signal is separated into a horizontal drive control signal and a vertical drive control signal. The light beam is amplified by the amplifiers 59a and 59b and sent to the horizontal drive adjusting means 55 and the vertical drive adjusting means 54, respectively, whereby the optical axis adjusting mirror driving mechanism 53 is connected so that the optical axis center of the light beam 51 is coupled to the optical fiber. Controlled.

[0005] As a support mechanism used for driving the mirrors 52 and 53, a ball bearing, a leaf spring or the like is used.

[0006]

In such a conventional light beam transmitting and receiving apparatus, a driving system for the vibrating mirror 52 and an optical axis adjusting mirror driving mechanism 53 for coupling the light beam 51 to the optical fiber are provided separately. In addition, it has been difficult to reduce the size of the device. Further, when a ball bearing is used for driving the mirror, there is a problem that lubrication is difficult when used in outer space. Even if the lubrication problem is solved by using a leaf spring, the mounting space and the supporting range of the leaf spring depend on the deflection of the plate, and there is a problem that a wide range of support in the torsion direction of the plate cannot be performed. Was. Furthermore, in practical use, it cannot be said that there is sufficient margin for fatigue of mechanical elements.

The present invention has been made in view of the above circumstances, and has as its object to provide a light beam transmitting / receiving apparatus which can be downsized and can support and drive an optical fiber in a wide range.

[0008]

According to the present invention, there is provided a light beam transmitting / receiving apparatus comprising: an optical fiber for receiving a light beam; a fiber housing for housing the optical fiber; an elastic hinge for elastically supporting the fiber housing; Optical fiber driving means for displacing the optical fiber housed in the fiber housing section based on a signal, signal processing means for converting a light beam passing through the optical fiber into an electric signal, and microvibrating the optical fiber A vibration signal generating means for generating a signal for detecting the optical axis error when the light beam enters and exits the optical fiber based on an output of the signal processing means and an output of the micro vibration signal generating means. Optical axis error detecting means, and the optical axis error based on the optical axis error detected by the optical axis error detecting means and the output of the micro vibration signal generating means. Difference, characterized in that it comprises a control means for driving and controlling the optical fiber driving means so that the zero.

[0009]

FIG. 1 shows the configuration of an embodiment of a light beam transmitting / receiving apparatus according to the present invention. The light beam transmitting and receiving apparatus of this embodiment includes a light beam combining mechanism 1, a mirror driving mechanism 2, a beam splitter 3, an optical axis position detecting means 4, a driving control means 5, a signal processing means 6, an optical axis An error detecting unit 7, a communication unit 8, and a vibration operation adjusting unit 9 are provided.

The external light beam is transmitted to the mirror driving mechanism 2
The light is reflected by the mirror 2a driven by the light source 2 and transmitted to the beam splitter 3. This reflected light is split into two optical paths by the beam splitter 3. One of the separated lights is detected by the light detection device 4.
Then, based on the detection signal, the mirror driving mechanism 2 is driven so that the other of the separated lights enters the optical fiber 1a of the light beam combining mechanism 1.

The optical fiber 1a is driven and controlled by the drive control means 5 based on a vibration position control signal from the vibration operation adjusting means 9 so as to vibrate minutely. Optical fiber 1
The light incident on a is sent to the signal processing means 6 and converted into an electric signal. The optical axis error of the light beam incident on the optical fiber 1a is detected by the optical axis error detecting means 7 based on the converted electric signal and the vibration control position signal from the vibration operation adjusting means 9.

The detection of the optical axis error is performed as follows. Since the vibration frequency of the optical fiber 1a can be determined from the vibration control position signal from the vibration operation adjusting means 9, the vibration frequency component is detected from the optical fiber incident light amount signal output from the vibration processing means 6, whereby the vibration of the optical fiber 1a is detected. It is possible to know the change in the incident light amount due to the operation. Specifically, as shown in FIG. 4, when the optical fiber 1a is oscillating around the optical axis of the light beam (when oscillating in the range indicated by reference numeral 41), the amplitude of the light amount change is minimized. Become. Further, when the optical fiber 1a vibrates while being displaced from the optical axis (when vibrating in the range indicated by the reference numeral 45), the amplitude value of the change in the light amount increases. An axis error can be detected. The direction of the optical axis error, that is, in which direction the error is shifted, is determined by comparing the phase of the vibration control position signal output from the vibration operation adjusting means 9 and the phase of the light amount signal output from the signal processing means 6 with light. It can be obtained by comparison in the axis error detecting means 7.

The light beam combining mechanism 1 is driven by the drive control means 5 based on the optical axis error obtained in this way and the output of the vibration operation adjusting means 9, so that the optical axis of the light beam is It is led to the center of 1a. The drive signal output from the drive control means 5 at this time is a signal 35 shown in FIG. The drive signal 35 is transmitted to the optical axis error detecting means 7.
(That is, the low-frequency signal 37 shown in FIG. 3) is superimposed on a high-frequency component serving as a vibration operation signal of the optical fiber 1a. This high frequency component is the output of the vibration operation adjusting means 9.

The light beam whose optical axis is guided to the center of the optical fiber 1a is converted into an electric signal by the signal processing means 6, and the converted electric signal is sent to the communication means 8 so that the communication signal is transmitted. Can be obtained.

Next, a specific structure of the light beam combining mechanism 1 used in the above embodiment will be described with reference to FIG. FIG. 2A shows an appearance of the light beam combining mechanism, and FIG. 2B shows a cross section thereof. The cutting line BB shown in FIG.
FIG. 2 (c) shows a cross section cut by. The light beam coupling mechanism of this embodiment includes a fiber rod 11 and an elastic hinge 1.
2, four piezoelectric elements 13 and four elastic hinges 14a
And four elastic hinges 14 b and a case 15.

The optical fiber 10 into which the light beam is incident is housed in the fiber rod 11 with a part thereof protruding from one end of the fiber rod 11. Fiber rod 11
Is supported by an elastic hinge 12 so as to operate integrally with the elastic hinge 12. The elastic hinge 12 has a disk shape at both ends, and has a shape whose thickness becomes thinner toward the center 20, and is usually made by cutting a cylindrical material made of metal, for example. Therefore, the elastic hinge 12 has high rigidity in the axial direction (direction toward the center 20), but low rigidity in the radial direction (direction perpendicular to the axial direction).

One end of the elastic hinge 12 is in contact with the fiber rod 11, and the other end is attached to the lower lid 15c of the case 15 so as to be detachable in the axial direction.

Also, four elastic hinges 14 are provided on the disk of the elastic hinge 12 on the side where the fiber rod 11 is in contact.
a is attached. Each elastic hinge 14a has substantially the same shape as the elastic hinge 12, but a protrusion is provided on the disk attached to the elastic hinge 12, and this protrusion is provided on the disk of the elastic hinge 12. It is attached to the elastic hinge 12 by being fitted into the hole.

A piezoelectric element 13 is mounted on a disk of each elastic hinge 14a opposite to the side on which the elastic hinge 12 is mounted. An elastic hinge 14b is in contact with an end of each piezoelectric element 13 opposite to the elastic hinge 14a. Each elastic hinge 14b has the same shape as the elastic hinge 14a,
The disk on the side opposite to the side in contact with the piezoelectric element 13 is provided with a projection, and the projection is fitted into a hole provided in the upper lid 15b of the case 15 to be attached to the upper lid 15b.

Therefore, the light beam coupling mechanism controls the position of the fiber rod 11, that is, the optical fiber 10 by driving the disk of the elastic hinge 12 with the four piezoelectric elements 13. All four piezoelectric elements 13 are preloaded, and the two opposing elements are set as a set, and the set of piezoelectric elements 13 is driven to perform a differential operation.

The support by the elastic hinge is rigid in the hinge compression direction, that is, in the axial direction of the fiber rod 11, but is soft in the other direction. Therefore, there is no need to configure a support mechanism for each axis as in the case where a leaf spring-like elastic hinge is used.
Also, since the driving range of a general laminated piezoelectric element is small,
It is customary to realize the required driving range by combining the displacement enlarging mechanism, and when one set of one piezoelectric element is used, that is, when four piezoelectric elements are used as in this specific example,
A total of four sets of displacement magnifying mechanisms are required. However, when the elastic hinge 12 capable of biaxial support is used for the support mechanism of the fiber rod 11, the center 20 of the elastic hinge 12 is used as a fulcrum of the lever-like displacement enlarging mechanism, and the elastic hinge-shaped disk and the fiber rod 11 are used as arms. With this configuration, the displacement enlargement mechanism for four piezoelectric elements can be reduced to one. Therefore, it is possible to secure two degrees of freedom with a simple and compact mechanism, which can greatly contribute to miniaturization of the entire light beam combining mechanism. Further, since the displacement enlarging mechanism is shared, smoother and more accurate driving of the optical fiber 10 can be realized.

Further, the piezoelectric element is used as the driving means because the piezoelectric element can generate displacement according to the command voltage, and the optical fiber driving operation for controlling the optical axis and the optical axis error described above. This is because the vibration operation for detection can be easily realized by generating the command voltage. However, it is known that the displacement / drive voltage characteristics of the piezoelectric element have hysteresis. For this reason, as described above, a method in which two piezoelectric elements are used for one axis and pre-loaded with a voltage of 耐 圧 of the withstand voltage, respectively, and differentially driven is adopted, and a signal having inverted characteristics is added. This hysteresis is canceled. Due to this differential drive, the disk on the elastic hinge 12 performs a rotational motion with two degrees of freedom about the center 20 of the elastic hinge 12 as the center of rotation. Therefore, a rotational motion with two degrees of freedom can be realized at the tip of the optical fiber 10, but the driving range of this mechanism in the tracking operation of the optical axis of the light beam and the vibration operation for detecting the optical axis is very small. , Which can be approximated to a translational motion.

Further, applying a preload to the piezoelectric element 13 means that a compressive stress is generated in the elastic hinges 12 and the elastic hinges 14a and 14b of the support mechanism, so that a tensile stress caused by a bending stress generated by driving the piezoelectric element 13 is generated. And the burden on the elastic hinges 12, 14a, 14b can be reduced. Moreover, the piezoelectric element 13 itself
Since the compressed state becomes steady, it can be used while avoiding the influence of an undesired load such as a tensile force. That is, an effect that a mechanism that can afford fatigue of the support mechanism and the driving unit can be expected.

On the other hand, the light beam combining mechanism of the present invention can be effectively utilized by being incorporated not only in a receiving device but also in a transmitting device. For example, when the transmission light is slightly vibrated by the present mechanism, the reflection mirror on the receiving side can easily catch the signal, and the driving range of the mirror driving mechanism can be reduced. In addition, if the transmitted light is slightly vibrated, the beam diameter can be reduced and a larger amount of received light can be incident, so that the mirror diameter can be reduced. That is, it is possible to contribute to the reduction of the burden of the capturing / tracking operation on the receiving side, and to the simplification and downsizing of the receiving device. Therefore, by constructing a system in which this mechanism is combined as a receiving device and a transmitting device, higher precision and larger capacity of optical communication can be expected.

As described above, by controlling the optical fiber directly by piezoelectric driving, the same function as the mechanism combining the vibrating mirror and the optical axis adjusting mirror can be realized by one mechanism. Further, the circular elastic hinge support enables a wide range of support with two degrees of freedom in a simple and compact configuration. Also, by preloading the piezoelectric element and driving it two differentials per axis, it suppresses the hysteresis of the displacement characteristics and reduces the load on the elastic hinge and the piezoelectric element. it can. In addition, with the same configuration and driving, it is possible to contribute to simplification and downsizing of the receiving side, and it is possible to construct an optical communication system with higher accuracy and larger capacity.

Incidentally, a solid actuator such as an electrostrictive element may be used instead of the piezoelectric element.

[0027]

As described above, it is possible to obtain an optical beam transmitting / receiving apparatus that can be downsized and can support and drive an optical fiber in a wide range.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a light beam transmitting / receiving apparatus according to the present invention.

FIG. 2 shows a specific structure of a light beam combining mechanism according to the light beam transmitting / receiving apparatus of the present invention.

FIG. 3 is a diagram showing an example of a drive signal of the light beam combining mechanism according to the embodiment shown in FIG.

FIG. 4 is an explanatory diagram of an optical axis error detection process.

FIG. 5 is a block diagram showing a configuration of a conventional light beam transmitting / receiving device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical beam coupling mechanism 1a Optical fiber 2 Mirror drive mechanism 2a Reflection mirror 3 Beam splitter 4 Optical axis position detection means 5 Drive control means 6 Signal processing means 7 Optical axis error detection means 8 Communication means 9 Vibration operation adjustment means 10 Optical fiber 11 Fiber rod 12 Elastic hinge 13 Piezoelectric element 14a, 14b Elastic hinge 15 Case 15a Case outer frame 15b Case upper lid 15c Case lower lid 20 Center of elastic hinge 35 Drive signal 37 Signal 41 Area near optical axis 45 Area off optical axis

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical indication location H04B 10/26 10/04 10/06 (72) Inventor Shigeharu Nakamori 2 Sengen 2 Tsukuba, Ibaraki Pref. No. 1-1, Space Development Agency Tsukuba Space Center (72) Inventor Fumika Kondo 1 Komukai Toshiba-cho, Koyuki-ku, Kawasaki-shi, Kanagawa Prefecture Toshiba R & D Center (72) Inventor Kenichi Takahara (72) Inventor: Toshikatsu Akiha Toshikatsu Akiha, Komukai Toshiba-cho, Kawasaki-shi, Kanagawa 1

Claims (2)

[Claims] An optical fiber for receiving the light beam; a fiber housing for housing the optical fiber; an elastic hinge for elastically supporting the fiber housing; and an elastic hinge housed in the fiber housing based on a drive signal. Optical fiber driving means for displacing the optical fiber, signal processing means for converting a light beam passing through the optical fiber into an electric signal, and micro vibration signal generating means for generating a signal for micro vibration of the optical fiber, Optical axis error detecting means for detecting an optical axis error when the light beam enters and exits the optical fiber based on an output of the signal processing means and an output of the micro vibration signal generating means; The optical axis error detected by the means,
Control means for controlling the driving of the optical fiber driving means so that the optical axis error becomes zero based on the output of the micro vibration signal generating means. 2. The light beam according to claim 1, wherein said driving means has a preloaded piezoelectric element or electrostrictive element, and said elastic hinge has a structure capable of supporting two axes. Transceiver.