JP4020255B2 - Variable optical attenuator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention Variable optical attenuator In particular, a MEMS device, a variable optical attenuation system, an optical attenuation method, an MEMS variable optical attenuator, and a wavelength branch that performs optical attenuation for each wavelength using the same, driven by a microelectromechanical system to perform optical attenuation It is useful when applied to a type of optical attenuator array.
[0002]
[Prior art]
<First prior art>
The first conventional technique will be described with reference to FIG. The prior art includes an input optical fiber 01, an output optical fiber 02, a circulator 03, an input / output optical fiber 04, a lens 05 with a focal length f, and a rotary drive mirror 06. The circulator 03 is an element whose light output port varies depending on the traveling direction of light. In FIG. 36, there are three ports 03-1, 03-2, and 03-3. The light that goes out to 03-2 and enters from the port 03-2 has a function of going out to the port 03-3.
[0003]
The axis connecting the center of the end face of the input / output optical fiber 04 and the center of the lens 05, the center axis of the lens 05, and the normal of the reflecting mirror surface of the rotary drive mirror 06 coincide. The distance from the end face of the input / output optical fiber 04 to the lens 05 is substantially equal to the focal length f.
[0004]
In such an optical system, functions will be described along the light traveling direction. The input light enters the circulator 03 from the port 03-1 through the input optical fiber 01, exits from the port 03-2, and enters the input / output optical fiber 04. The divergent light from the end face of the input / output optical fiber 04 is collimated through the lens 05. The collimated light is applied to the reflecting mirror surface of the rotary drive mirror 06, reflected by the reflecting mirror surface, and then converges again through the lens 05 and forms an image on the end surface of the input / output optical fiber 04. As a result, the input / output optical fiber 04 is entered. When the circulator 03 is entered from the port 03-2 via the input / output optical fiber 04, it exits to the port 03-3 due to the characteristics of the circulator 03. It enters the output optical fiber 02 from the port 03-3 and goes out of the apparatus.
[0005]
In such a conventional technique, when the line connecting the center of the input / output optical fiber 04 and the center of the optical axis of the lens 05 coincides with the normal direction of the reflecting mirror surface of the rotary drive mirror 06, the image formation position of the convergent light As a result, the light returning to the output optical fiber 02 is maximized. Here, when the rotary drive mirror 06 is rotated, the imaging position of the convergent light is shifted from the position of the core on the end face of the input / output optical fiber 04, and the light returning to the output optical fiber 02 decreases. Using this action, the light attenuation rate is variably controlled by adjusting the rotation angle of the rotary drive mirror 06.
[0006]
<Second prior art>
The second conventional technique will be described with reference to FIG. The prior art includes an input optical fiber 011, an output optical fiber 012, a lens 015 having a focal length f, and a rotary drive mirror 016. Here, the axis connecting the midpoint of the line connecting the input optical fiber 011 and the output optical fiber 012 and the center of the lens 015, the center axis of the lens 015, and the normal of the reflecting mirror surface of the rotary drive mirror 016 coincide. ing. The distances from the input optical fiber 011 and the output optical fiber 012 to the lens 015 are substantially equal to the focal length f.
[0007]
In such an optical system, divergent light from the input optical fiber 011 is collimated via the lens 015. The collimated light is irradiated on the reflecting mirror surface of the rotary drive mirror 016. Thereafter, the light is reflected on the reflecting mirror surface, is again converged through the lens 015, is focused on the end face of the output optical fiber 012, and enters the output optical fiber 012.
[0008]
In such prior art, the line connecting the midpoint between the centers of the input optical fiber 011 and the output optical fiber 012 and the optical axis center of the lens 015 coincides with the normal direction of the reflecting mirror surface of the rotary drive mirror 016. In this case, the image forming position of the convergent light coincides with the position of the core of the output optical fiber 012, and the light returning to the output optical fiber 012 is maximized. Here, when the rotary drive mirror 016 is rotated, the light that returns to the output optical fiber 012 is reduced by shifting the focusing light imaging position from the position of the core on the end face of the output optical fiber 012. Using this action, the light attenuation rate is variably controlled by adjusting the rotation angle of the rotary drive mirror 016.
[0009]
Here, FIG. 38 shows the relationship between the rotation angle of the rotary drive mirror 016 and the light attenuation rate when the lens 015 having a focal length f = 1.2 mm is used. In the figure, the vertical axis represents the attenuation rate (dB), and the horizontal axis represents the rotation angle (radian).
[0010]
As is apparent from FIG. 38, when a lens 015 having a focal length f of 1.2 mm is used, a rotation of 0.005 radians is required to attenuate about 20 dB. If the numerical aperture (NA) of the fiber is 0.1, the beam irradiation area on the reflecting mirror surface in this system is about 240 μm.
[0011]
<Third prior art>
The third prior art will be described with reference to FIG. The prior art is an array of variable optical attenuators I according to the first prior art and the second prior art, and the variable optical attenuator I according to the first prior art or the second prior art. Are arranged in parallel and installed in the same housing II so that they can be used easily. In the figure, III is an input and output optical fiber group.
[0012]
<Fourth prior art>
The fourth conventional technique will be described with reference to FIG. The related art is a waveguide-type variable optical attenuator, and includes an input optical port 041, a waveguide Mach-Zehnder interferometer 042, and a heater 043 installed to heat one optical path of the waveguide Mach-Zehnder interferometer 042. The control line 044 for supplying current to the heater 043 and the output port 045 are configured. This waveguide-type variable optical attenuator is abbreviated as VOA (Variable Optical Attenuator).
[0013]
In such a conventional technique, since the temperature of both optical paths is usually the same, there is no optical path length difference between the optical paths, and light from both optical paths interferes, and the output port 045 has the maximum light intensity. can get. Here, when the current of the control line 044 is passed to heat the heater 043 and the temperature of one optical path rises, an optical path length difference is generated. As a result, the interference is weakened and the light intensity obtained at the output port 045 is Decrease. When there is a temperature difference that causes a half-wavelength optical path length difference, the light between the two optical paths cancel each other, and the light intensity obtained at the output port 045 is minimized.
[0014]
FIG. 41 shows an outline of the dependence of the relative intensity of light at the output port 045 on the temperature difference. As is apparent from the figure, it has a cosine function dependence on the temperature difference. Therefore, the light intensity obtained at the output port 045 can be controlled by adjusting the temperature difference with the current of the heater 043.
[0015]
<Fifth prior art>
The fifth prior art will be described with reference to FIG. This prior art is obtained by integrating a plurality of variable optical attenuators according to the fourth prior art on a single waveguide substrate 051. According to the fifth prior art, the optical attenuation can be controlled independently for each channel. In FIG. 42, the same parts as those in FIG. 40 are denoted by the same reference numerals, and redundant description is omitted.
[0016]
<Sixth Prior Art>
The sixth conventional technique will be described with reference to FIG. The prior art includes an input optical fiber 062, a demultiplexing array waveguide diffraction grating 063, a variable optical attenuator array 064, a multiplexing array waveguide diffraction grating 065, and an output optical fiber 066. Are connected. The arrayed waveguide grating demultiplexes the input light consisting of many wavelengths to a different port for each wavelength, and combines the light of different wavelengths input from different ports and outputs it to one port (Hereinafter, abbreviated as AWG (Arrayed Waveguide Grating)). These are arranged and integrated on one waveguide substrate 061. The variable optical attenuator array 064 is a collection of waveguide Mach-Zehnder interferometers 042 shown in FIG. Each variable optical waveguide Mach-Zehnder interferometer 042 is connected to a control line 044 for controlling the optical attenuation for each channel. The arrayed waveguide diffraction gratings 063 and 065 have the same demultiplexing / multiplexing performance.
[0017]
In such a conventional technique, input light entering from the input optical fiber 062 is demultiplexed into a plurality of channels according to the wavelength when passing through the demultiplexing AWG063. Next, the variable optical attenuator array 064 is reached for each channel and attenuated for each channel. Here, the light attenuation amount control line 044 is controlled by a current amount representing the light attenuation amount. After passing through this variable optical attenuator array 064, light of different wavelengths that have undergone different attenuation by the multiplexing AWG 065 is multiplexed and output from the output optical fiber 066.
[0018]
The following non-patent document 1 exists as a known document disclosing this type of variable optical attenuator.
[0019]
[Non-Patent Document 1]
C. R Doerr, R.A. Pafchek, and L.L. W. Stulz IEEE Photonics Technology Letters, vol. 14, no. 3 page 334-336 (2002).
[0020]
[Problems to be solved by the invention]
In the variable optical attenuator of the drive system such as the first and second prior art rotary drive mirrors 06 and 016, the mirror surface is irradiated with collimated light to the mirror that controls the amount of light attenuation. Light is irradiated to the wide area above. If the mirror is curved, there is a disadvantage that it will be lost unexpectedly because it will not become a focal point when it returns to the end face of the optical fiber. In addition, since a mirror having a large area is required, the mass of the mirror is increased, the resonance frequency is lowered, and the rotation angle cannot be changed at high speed.
[0021]
Further, the light attenuation action is caused by the position of the core on the end face of the input / output optical fiber 04 in the first prior art or the output optical fiber 012 in the second prior art, and the position of the light returning from the lens 015. Therefore, if the rotation axis of the rotary drive mirror 016 and the normal direction of the light reflecting surface are deviated from the intended direction, the reflected light is also incident on the end face of the optical fiber by the rotation of the mirror. If it cannot be reached, there is a drawback that it is difficult to use an adjustment means such as obtaining the optimum direction of the mirror by grasping the light increasing / decreasing tendency. For this purpose, it is necessary to make fine adjustments with respect to the rotation axis direction of the mirror and the normal direction of the light reflecting surface of the mirror.
[0022]
In the third prior art, a variable optical attenuator is individually manufactured for each channel, and finally, a plurality of optical attenuators are collectively installed and arrayed. In this method, downsizing and multi-channeling are adopted. There was a limit.
[0023]
Further, in the fourth to sixth prior arts, the variable optical attenuator controls the optical attenuation amount by the amount of current flowing through the control line 044, and in order to maintain a specific optical attenuation amount, the current is always changed. The apparatus must be kept flowing, the power consumption is large, a heat problem occurs, and a cooler is required for temperature control, which makes the apparatus complicated and expensive. Furthermore, in the sixth prior art, in order to monitor the input spectrum and the output spectrum, an optical spectrum analyzer for monitoring is necessary, which is expensive and large.
[0024]
In view of the above-described conventional technology, the present invention can be driven at high speed, can reduce the trouble of fine position adjustment at the time of manufacture, and can be reduced in size and power consumption. Variable optical attenuator The purpose is to provide.
[0025]
[Means for solving the problems]
The configuration of the present invention that achieves the above object is characterized by the following points.
[0026]
[0027]
[0028]
input Optical fiber, output optical fiber, circulator, input / output optical fiber, first lens with a first focal length f1, and second lens with a second focal length f2, can be translated. In a variable optical attenuator having a translational mirror,
The distance from the end face of the input / output optical fiber to the first lens is f1, and the distance from the first lens to the second lens is f1 + f2, from the second lens to the translation drive. The distance to the mirror is f2, and it is arranged to focus on the mirror surface of the translation drive mirror,
Light radiated from the end face of the input / output optical fiber via the input optical fiber and the circulator is reflected on the mirror surface of the translation drive mirror via the first lens and the second lens. Then, the optical path is again formed so as to return to the end face of the input / output optical fiber via the second lens and the first lens, and again toward the output optical fiber via the circulator. on the other hand,
By driving the translation drive mirror in translation, the coupling efficiency of the return light at the end face of the input / output optical fiber to the input / output optical fiber is changed, and the output with respect to the intensity of light from the input optical fiber is changed. To control the attenuation factor of light intensity in optical fiber.
[0029]
[0030]
[0031]
[0032]
[0033]
[0034]
[0035]
[0036]
[0037]
[0038]
[0039]
[0040]
[0041]
[0042]
[0043]
[0044]
[0045]
[0046]
[0047]
[0048]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0049]
< First reference example >
Figure 1 First reference example It is explanatory drawing which shows notionally the structure of the variable optical attenuator which concerns on. As shown in the figure, the variable optical attenuator includes an input optical fiber 1, an output optical fiber 2, a circulator 3, an input / output optical fiber (core diameter 11 μm) 4, a lens 5 with a focal length f, and a rotational drive. It has a mirror 6.
[0050]
Here, the axis connecting the center of the end face of the input / output optical fiber 4 and the center of the lens 5, the center axis of the lens 5, and the normal of the reflecting mirror surface of the rotary drive mirror 6 coincide. The distance from the end face of the input / output optical fiber 4 to the lens 5 is substantially equal to 2f. The distance from the lens 5 to the reflecting mirror surface of the rotary drive mirror 6 is also approximately equal to 2f.
[0051]
The function of such a variable optical attenuator will be described. The input light enters the circulator 3 from the port 3-1 via the input optical fiber 1 and exits from the port 3-2. Further, it enters the input / output optical fiber 4. The divergent light from the end face of the input / output optical fiber 4 passes through the lens 5 and is focused on the reflecting mirror surface of the rotary drive mirror 6.
[0052]
The size of the focal point on the reflecting mirror surface of the rotary drive mirror 6 is substantially equal to the core diameter (11 μm) of the input / output optical fiber 4.
[0053]
The light reflected by the reflecting mirror surface becomes divergent light, and again forms convergent light via the lens 5 and forms an image on the end face of the input / output optical fiber 4. As a result, the input / output optical fiber 4 is entered. When the circulator 3 is entered from the port 3-2 via the input / output optical fiber 4, it exits to the port 3-3 due to the characteristics of the circulator 3. The light enters the output optical fiber 2 from the port 3-3 and is output to the outside.
[0054]
In such a variable optical attenuator, when the center of the input / output optical fiber 4 is coaxial with the optical axis of the lens 5, convergent light is imaged at the core position of the input / output optical fiber 4. In particular, when the reflecting mirror surface of the rotary drive mirror 6 is perpendicular to the optical axis of the lens 5, the convergent light is input perpendicularly to the end surface of the input / output optical fiber 4 and is taken into the input / output optical fiber 4 at this time. The light intensity is maximized. When the rotary drive mirror 6 is rotated from this state, the incident angle of the convergent light with respect to the end face of the input / output optical fiber 4 deviates from the vertical, and the light returning to the output optical fiber 2 decreases. By utilizing this action, the light attenuation rate is variably controlled by adjusting the rotation angle of the rotary drive mirror 6.
[0055]
FIG. 2 shows data obtained by measuring the rotation angle dependence of the optical attenuation factor in the variable optical attenuator. In this data, the curve of the rotation angle dependence of the light attenuation factor is data of f = 700 μm and f = 1200 μm, but they are overlapped and hardly depend on the focal length f. Therefore, the degree of freedom in selecting the lens 5 is considerably increased.
[0056]
For example, when designing a variable optical attenuator capable of obtaining a loss of 20 dB at a rotation angle of 0.096 radians, a desired small variable optical attenuator is realized by using, for example, the lens 5 having a focal length of 700 μm. it can.
[0057]
Here, it is assumed that the reflecting mirror surface of the rotary drive mirror 6 at the time of manufacturing the variable optical attenuator according to the present embodiment is deviated from perpendicular to the optical axis of the lens 5 in the initial state. Even in this case, the focus position where the light reflected from the mirror surface of the rotary drive mirror 6 is again collected by the optical system is always at the center position of the input / output optical fiber 4, so the increasing / decreasing tendency of the return light can be grasped. By doing so, it is possible to easily search for the position of the rotary drive mirror 6 at which the amount of return light is maximized.
[0058]
< Second reference example >
Figure 3 Second reference example It is explanatory drawing which shows notionally the structure of the variable optical attenuator which concerns on. As shown in the figure, the variable optical attenuator includes an input optical fiber 11, an output optical fiber 12, a circulator 13, an input / output optical fiber (core diameter 11 μm) 14, a lens 15 having a focal length f1, a focal length. An f2 lens 17 and a rotary drive mirror 16 are provided.
[0059]
Here, the axis connecting the center of the end face of the input / output optical fiber 14 and the centers of the lenses 15 and 17, the central axis of the lenses 15 and 17, and the normal of the reflecting mirror surface of the rotary drive mirror 16 coincide. The distance from the end face of the input / output optical fiber 14 to the lens 15 is substantially equal to the focal length f1. The distance from the lens 15 to the lens 17 is substantially equal to f1 + f2. Furthermore, the distance from the lens 17 to the mirror surface of the rotary drive mirror 16 is substantially equal to the focal length f2.
[0060]
The function of such a variable optical attenuator will be described. The input light enters the circulator 13 from the port 13-1 via the input optical fiber 11, and exits from the port 13-2. Further, the optical fiber enters the input / output optical fiber 14. The divergent light from the end face of the input / output optical fiber 14 passes through the lens 15 to become collimated light, travels a distance f1 + f2, and reaches the lens 17. The light is converged by the lens 17 and is focused on the reflecting mirror surface of the rotary drive mirror 16.
[0061]
Here, the size of the focal point on the reflecting mirror surface of the rotary drive mirror 16 is about the core diameter (11 μm) × (f2 / f1) of the input / output optical fiber 14. The light reflected by the reflecting mirror surface becomes divergent light and again becomes collimated light via the lens 17, reaches the lens 15, and becomes convergent light by the lens 15 and forms an image on the end face of the input / output optical fiber 14. To do. As a result, the input / output optical fiber 14 is entered. When entering the circulator 13 from the port 13-2 via the input / output optical fiber 14, it exits to the port 13-3 due to the characteristics of the circulator 13. Thereafter, the light enters the output optical fiber 12 from the port 13-3 and exits from the variable optical attenuator.
[0062]
In such a variable optical attenuator, when the optical axes of the lens 15 and the lens 17 coincide and the center of the input / output optical fiber 14 is on the same axis, the convergent light is positioned at the core position of the input / output optical fiber 14. Is imaged. In particular, when the reflecting mirror surface of the rotary drive mirror 16 is perpendicular to the optical axes of the lens 15 and the lens 17, the convergent light is input perpendicularly to the end surface of the input / output optical fiber 14. At this time, the amount of light taken into the input / output optical fiber 14 is maximized. When the rotary drive mirror 16 is rotated from this state, the incident angle of the convergent light with respect to the end face of the input / output optical fiber 14 deviates from the vertical, and the light returning to the output optical fiber 12 decreases. By utilizing this action, the light attenuation rate is variably controlled by adjusting the rotation angle of the rotary drive mirror 15.
[0063]
FIG. 4 shows data obtained by measuring the rotation angle dependence of the optical attenuation factor in the variable optical attenuator. As can be seen from this data, the rotation angle dependence curve of the light attenuation rate in this embodiment depends not on the value of the focal length itself but on the ratio of the focal lengths f1 and f2 of the two lenses 15 and 17.
[0064]
Therefore, when it is desired to construct an optical system that has an attenuation factor of a certain rotation angle using this relationship, a desired attenuation factor is determined by determining the ratio of the focal lengths f1 and f2 of the two lenses 15 and 17. The variable optical attenuator can be designed so as to obtain the relationship between the rotation angle and the rotation angle.
[0065]
For example, when designing a variable optical attenuator that can obtain a loss of 20 dB at a rotation angle of 0.1 radians, the ratio of the focal lengths f1 and f2 between the lens 15 and the lens 17 is set to 1, for example, the focal length is set as the lens 15. A desired variable optical attenuator can be realized by using a lens having a focal length of 700 μm (= f2) as the lens 17 and 700 μm (= f1). Further, when designing a variable optical attenuator that can obtain a loss of 20 dB at a rotation angle of 0,016 radians, the ratio of the focal length of the lens 15 and the lens 17 is 0.16, for example, the focal length is 115 μm as the lens 15. (= F1) By using a lens having a focal length of 700 μm (= f2) as the lens 17, a desired variable optical attenuator can be realized.
[0066]
Here, it is assumed that the reflecting mirror surface of the rotary drive mirror 16 at the time of manufacturing the variable optical attenuator according to the present embodiment is deviated from perpendicular to the optical axes of the lens 15 and the lens 17 in the initial state. Even in this case, although the incident angle of the return light to the input / output optical fiber 14 is not vertical, the focus position is always in the core portion of the input / output optical fiber 14, so that the tendency of increase / decrease in the intensity of the return light can be grasped. By doing so, it is possible to search for the position of the rotary drive mirror 16 at which the amount of return light is maximized.
[0067]
< Embodiment of the present invention >
FIG. Embodiment of the present invention It is explanatory drawing which shows notionally the structure of the variable optical attenuator which concerns on. As shown in the figure, the variable optical attenuator includes an input optical fiber 21, an output optical fiber 22, a circulator 23, an input / output optical fiber (core diameter 11 μm) 24, a lens 25 having a focal length f1, a focal length. An f2 lens 27 and a translational drive mirror 26 are provided.
[0068]
Here, the axis connecting the center of the end face of the input / output optical fiber 24 and the center of the lens 25, the center axis of the lens 27, and the normal line of the reflecting mirror surface of the translation drive mirror 26 coincide. The distance from the end face of the input / output optical fiber 24 to the lens 25 is substantially equal to the focal length f1. The distance from the lens 25 to the lens 27 is substantially equal to f1 + f2. Further, the distance from the lens 27 to the reflecting mirror surface of the translation drive mirror 26 is substantially equal to the focal length f2.
[0069]
The function of such a variable optical attenuator will be described. The input light enters the circulator 23 from the port 23-1 via the input optical fiber 21, and exits from the port 23-2. Thereafter, the input / output optical fiber 24 is entered. The divergent light from the end face of the input / output optical fiber 24 passes through the lens 25 to become collimated light, travels through the focal length f1 + f2, and reaches the lens 27. The light is converged by the lens 27 and is focused on the reflecting mirror surface of the translation drive mirror 26. The size of the focal point on the reflecting mirror surface is about the core diameter (11 μm) × (f2 / f1) of the input / output optical fiber 24. The light reflected by the translational drive mirror becomes divergent light and again becomes collimated light via the lens 27, reaches the lens 25, is converged by the lens 25, and is connected to the end face of the input / output optical fiber 24. Image. As a result, the optical fiber 24 enters the input / output optical fiber 24. When the circulator 23 is entered from the port 23-2 via the input / output optical fiber 24, it exits to the port 23-3 due to the characteristics of the circulator 23. Thereafter, the light enters the output optical fiber 22 from the port 23-3 and is output to the outside of the variable optical attenuator.
[0070]
In such a variable optical attenuator, when the optical axes of the lens 25 and the lens 27 coincide and the center of the input / output optical fiber 24 is on the same axis, the convergent light is positioned at the core position of the input / output optical fiber 24. Is imaged. In particular, when the position of the reflecting mirror surface of the translation drive mirror 26 coincides with the focal position, the convergent light input to the end face of the input / output optical fiber 24 is in a state of focusing at the end face position. The amount of light taken into the output combined optical fiber 24 is maximized. When the translation drive mirror 26 is moved from this state, the center position of the focal point becomes. Although it coincides with the center of the input / output optical fiber 24, the focal position deviates from the position of the end face of the input / output optical fiber 24 and is defocused, and the light returning to the output optical fiber 22 decreases. Using this action, the light attenuation rate is variably controlled by adjusting the moving distance of the translation drive mirror 26.
[0071]
FIG. 6 shows data obtained by measuring the translational distance dependency of the optical attenuation factor in the variable optical attenuator. As can be seen from this data, the translational distance dependency curve of the light attenuation rate in this embodiment depends on the ratio of the focal lengths f1 and f2 of the two lenses 25 and 27, not the values of the focal lengths f1 and f2. . Therefore, when it is desired to configure an optical system that has a predetermined attenuation rate at a certain translational distance by using this relationship, the ratio of the focal lengths f1 and f2 of the two lenses 25 and 27 is determined to be desired. It is possible to design a variable optical attenuator that obtains the relationship between the attenuation rate of the light source and the translational movement distance.
[0072]
For example, when it is desired to design a variable optical attenuator that can obtain a loss of 20 dB at a translational distance of 17 μm, the ratio of the focal lengths of the lens 25 and the lens 27 may be set to 6. For example, by using a lens having a focal length of 700 μm (= f1) as the lens 25 and a lens having a focal length of 115 μm (= f2) as the lens 27, a desired variable optical attenuator can be realized.
[0073]
Here, it is assumed that the initial position of the translation mirror at the time of manufacturing the variable optical attenuator according to the present embodiment is shifted from the position where the maximum amount of return light can be obtained. Even in this case, since the center position of the focal point of the return light is always on the central axis of the core of the input / output optical fiber 24, the amount of the return light can be maximized by grasping the increasing / decreasing tendency of the intensity of the return light. The position of the translation movable mirror 26 can be searched.
[0074]
< Third reference example >
FIG. Third reference example It is explanatory drawing which shows notionally the structure of the variable optical attenuator array which concerns on. The variable optical attenuator array according to this embodiment is First reference example It has a structure in which a large number of variable optical attenuators based on the optical attenuation principle are integrated.
[0075]
As shown in FIG. This form A variable optical attenuator array in which a large number of variable optical attenuators are integrated includes an input optical fiber group 31 composed of a plurality of optical fibers, an output optical fiber group 32 composed of a plurality of optical fibers, and a plurality of circulators 33. , An optical fiber group 34 for both input and output in which end faces of a plurality of optical fibers are aligned and arranged at regular intervals, a glass spacer 37, a lens array 35 in which a plurality of lenses having a focal length of 700 μm are arranged in parallel, and an optical distance of 1400 μm Remote place A MEMS array 36 which is a rotationally driven mirror array, and a MEMS electrode 39.
[0076]
Here, the glass spacer 37 has a thickness of 403 μm, the lens array 35 has a thickness of 530 μm, and the optical distance from the input / output optical fiber group 34 to the lens array 35 has a refractive index of 1. 5, the optical distance is 1400 μm, the thickness of the glass spacer 38 is 517 μm, the distance in the air to the MEMS mirror array 36 is 625 μm, and the optical distance from the lens array 35 to the MEMS mirror 39 is also 1400 μm. It is.
[0077]
Here, the lens array 35 will be briefly described with reference to FIG. FIG. 8A is a top view thereof, and FIG. 8B is a side view thereof. As shown in both figures, the lens array 35 is commercially available, and a number of refractive index distribution lenses 35b are formed in the vicinity of the surface of the glass substrate 35a with a period of 250 μm between the centers, and the thickness is 530 μm. .
[0078]
Next, the structure of the MEMS mirror array 36 will be described with reference to FIG. FIG. 2A is a perspective view thereof, FIG. 2B is a sectional view thereof A, and FIG. As shown in these drawings, the MEMS mirror array 36 includes a MEMS mirror array substrate 36a as an upper portion and a MEMS drive electrode substrate 36b as a lower portion.
[0079]
In particular, as shown in FIG. 9B and FIG. 9C, since the MEMS drive electrode substrate 36b has a recessed portion, the mirror 36c constituting the MEMS mirror array substrate 36 is separated from the MEMS mirror array portion 36a. It is supported by the spring only and held in the air. Further, a light blocking barrier 36d is provided between the single mirrors 36c so that stray light from adjacent mirrors 36c is blocked.
[0080]
FIG. 10 is a top view of the upper MEMS mirror array substrate. As shown in the figure, a mirror 36c, a light blocking barrier 36d, and a torsion spring 36e are integrally formed on the MEMS mirror array substrate.
[0081]
FIG. 11 is a top view of the lower MEMS drive electrode substrate 36b. Here, the pad electrode 36f and the drive electrode 36g are electrically insulated from the upper rotating mirror. A pair of drive electrodes 36g corresponding to the mirror 36c, which is one micro rotating mirror, is provided, and electrostatic attraction is generated by applying a voltage to the drive electrodes 36g via the pad electrode 36f. Then, the mirror 36c is rotationally driven to a desired angle. In addition, there is a separate ground electrode pad 36i, which is electrically connected to the upper rotary mirror and connected to the ground.
[0082]
Also this Third reference example In First reference example The relationship between the rotation angle and the attenuation rate is also First reference example The same characteristics can be obtained.
[0083]
The rotary drive mirror array in the variable optical attenuator shown in this embodiment can be manufactured in a batch by a micromachining technique based on a semiconductor process technique.
[0084]
The production method is described below. First, a method for manufacturing the upper MEMS mirror array substrate will be described.
[0085]
FIG. 12 shows the mask used. FIG. 5A shows a substrate-side etching pattern, and FIG. 5B shows a mirror and spring portion forming pattern. The substrate side etching pattern is a mask for engraving from the back surface, and the mirror and spring part forming pattern is a mask for forming the mirror 36c and the torsion spring part 36e.
[0086]
The upper mirror array creation process will be described with reference to FIG.
(1) An SOI (Si1 icon on Insulator) substrate is prepared. This substrate is composed of a Si substrate having a silicon active layer of 3 μm, a buried Si oxide layer of 1 μm, and a thickness of 625 μm.
(2) A photolithography process is performed on the Si active layer using the first upper MEMS mirror array mask (FIG. 12B) to form a torsion spring portion and a MEMS mirror.
(3) The substrate is turned upside down.
(4) A photolithography process is performed on the Si substrate using the second upper MEMS mirror array mask (FIG. 12A), and etching is performed at a depth of 625 μm using the Deep Reactive Ion Etching apparatus. Do.
(5) Dicing is performed to divide each chip, and the embedded Si oxide layer is removed.
(6) A Cr layer and an Au layer are formed.
(7) A Cr layer and an Au layer are formed from the back surface.
[0087]
Next, a manufacturing method of the lower MEMS drive electrode substrate will be described. FIG. 14 shows the mask used. As shown in the figure, (a) is a mask for forming an electrode forming pattern, and (b) is a mask for engraving by anisotropic etching. In the figure, 36g is a pair of drive electrodes, 36h is a drive electrode pad, 36i is a ground electrode pad, and 36j is a thermal oxide film pattern.
[0088]
The lower MEMS drive electrode substrate manufacturing process will be described with reference to FIG.
(1) A Si (100) substrate is prepared. This substrate has a thickness of 625 μm.
(2) A Si thermal oxide film is formed.
(3) A photolithography process is performed on the Si thermal oxide film using the first lower MEMS drive electrode substrate mask (FIG. 14B) to form a pattern.
(4) An anisotropic etching is performed using an aqueous potassium hydroxide solution or the like to form a recess having a depth of 40 μm.
(5) A Si thermal oxide film is formed.
(6) Evaporate Cr and Au.
(7) A photolithography process is performed using the second lower MEMS drive electrode substrate mask (FIG. 14A) to form electrode patterns of Au and Cr layers.
[0089]
A structure as shown in FIG. 16 may be used as a structure that enables the same action. This is a top view, and includes a mirror 36k and a torsion spring portion 36l. The torsion spring 36l extends in the longitudinal direction of the opening, and a simple bar is used as the torsion spring. Since a simple rod is used, the tension spring constant can be hardened while keeping the torsion spring soft, and operations other than rotation can be suppressed.
[0090]
FIG. 17 shows a part of the mask for the MEMS drive electrode substrate. As shown in the figure, a drive electrode 36m and a pad electrode 36n for rotating the mirror around the axis of the torsion spring are arranged. Further, a separate ground electrode pad 36i is provided, and is electrically connected to the upper rotary mirror, and the drive electrode 36m and the pad electrode 36n connected to the ground are electrically insulated from the upper rotary mirror.
[0091]
< Fourth reference example >
FIG. Fourth reference example It is explanatory drawing which shows notionally the structure of the variable optical attenuator array which concerns on. The variable optical attenuator array according to this embodiment is Second reference example It has a structure in which a large number of variable optical attenuators based on the optical attenuation principle are integrated.
[0092]
As shown in FIG. 18, a variable optical attenuator array in which a large number of variable optical attenuators according to this embodiment are integrated includes an input optical fiber group 41 composed of a plurality of optical fibers and an output optical fiber composed of a plurality of optical fibers. A lens in which a group 42, a plurality of circulators 43, an input / output optical fiber group 44 in which end faces of a plurality of optical fibers are aligned and arranged at a constant interval, a glass spacer 48, and a plurality of lenses having a focal length of 700 μm are arranged in parallel. An array 45, a lens array 47 in which a plurality of lenses having a focal length of 700 μm are arranged in parallel, a MEMS mirror array 46 that is a rotationally driven mirror array installed at a distance of 625 μm, and a MEMS electrode 49 are provided.
[0093]
Here, the thickness of the glass spacer 48 is 595 μm, the thickness of the lens arrays 45 and 47 is 530 μm, and the optical distance from the input / output optical fiber group 44 to the lens array 45 is the refractive index of the glass. 1.5 is 700 μm, and the distance in the air from the lens array 47 to the mirror in the MEMS mirror array 46 is 625 μm.
[0094]
Regarding the MEMS mirror array 46 in this embodiment, Third reference example The same structure as the MEMS mirror array 36 in FIG. Also for the top view of the rotating mirror Third reference example 11 or 16 in FIG. 16, and the electrode for rotation drive Third reference example The same as FIG. 11 or FIG.
[0095]
The structure and manufacturing method of the MEMS mirror array 46 in this embodiment are as follows: Third reference example Are omitted here.
[0096]
FIG. 19 shows data on the rotation angle dependency of the light attenuation rate in this embodiment. Here, since the optical attenuator according to the second reference example is used, the relationship between the rotation angle and the attenuation rate is also described. Second reference example Similar data is obtained.
[0097]
< Fifth reference example >
FIG. Fifth reference example It is explanatory drawing which shows notionally the structure of the variable optical attenuator array which concerns on. The variable optical attenuator array according to this embodiment is Embodiment of the present invention It has a structure in which a large number of variable optical attenuators based on the optical attenuation principle are integrated.
[0098]
As shown in FIG. 20, the variable optical attenuator array in which many variable optical attenuators according to this embodiment are integrated includes an input optical fiber group 51 composed of a plurality of optical fibers and an output optical fiber composed of a plurality of optical fibers. A lens in which a group 52, a plurality of circulators 53, an input / output optical fiber group 54 in which end faces of a plurality of optical fibers are aligned at a constant interval, a glass spacer 58, and a plurality of lenses having a focal length of 700 μm are arranged in parallel. An array 55, a lens array 57 in which a plurality of lenses having a focal length of 115 μm are arranged in parallel, a MEMS mirror array 56 which is a translational drive mirror array installed at a distance of 115 μm, and a MEMS electrode 59 are provided.
[0099]
Here, the thickness of the glass spacer 58 is 595 μm, the thickness of the lens arrays 55 and 57 is 530 μm, and the optical distance from the input / output optical fiber group 54 to the lens array 55 is the refractive index of the glass. 1.5 is 700 μm, and the distance in the air from the lens array 57 to the mirror in the MEMS mirror array 56 is 115 μm.
[0100]
FIG. 21 shows a part of a top view of the mask pattern of the upper MEMS mirror array 56 and the lower drive electrode substrate used in this embodiment. As shown in the figure, the mirror 56a in the MEMS mirror array 56 is supported by a tension spring 56b from four directions and held in the air. By applying a voltage to the drive electrode 56c directly below the mirror 56a via the pad electrode 56d, an electrostatic attractive force is generated, and the mirror 56a is drawn toward the drive electrode 56c to cause a translational movement of the mirror 56a.
[0101]
The manufacturing method of the MEMS mirror array 56 that causes the translational movement as described above is as follows. Third reference example Since the method is the same as that described in the above and only the pattern is different, it is omitted here.
[0102]
FIG. 23 shows the translational distance dependency of the attenuation rate in this embodiment. In this form, Embodiment of the present invention The relationship between translational distance and attenuation rate is also Embodiment of the present invention Similar data is obtained.
[0103]
< Sixth reference example >
FIG. Sixth reference example It is explanatory drawing which shows notionally the structure of the variable optical attenuator array which concerns on. The variable optical attenuator array according to this embodiment has a structure in which a large number of variable optical attenuators based on the optical attenuation principle of the first prior art are integrated.
[0104]
As shown in FIG. This form A variable optical attenuator array in which a large number of variable optical attenuators are integrated includes an input optical fiber group 61 composed of a plurality of optical fibers, an output optical fiber group 62 composed of a plurality of optical fibers, and a plurality of circulators 63. , A group of optical fibers 64 for both input and output, in which end faces of a plurality of optical fibers are aligned at a constant interval, a glass spacer 67, a lens array 65 in which a plurality of lenses having a focal length f are arranged in parallel, and a constant distance in the air It has a MEMS array 66 which is a rotary drive mirror array installed at a distant place, and a MEMS electrode 69.
[0105]
Here, when the focal length f of the lens array 65 is 700 μm, the thickness of the glass spacer 67 is 467 μm, the thickness of the lens array 65 is 530 μm, and the thickness of the substrate of the MEMS mirror array 66 is 115 μm. It is. Therefore, the optical distance from the input / output optical fiber group 64 to the lens array 65 is 700 μm, and the optical distance from the lens array 65 to the MEMS mirror array 66 is 530 μm in thickness of the lens array 65 and 115 μm in the air. The sum is 968 μm.
[0106]
When the focal length f of the lens array 65 is 115 μm, the thickness of the glass spacer 67 is 77 μm, the thickness of the lens array 65 is 530 μm, and the thickness of the substrate of the MEMS mirror array 66 is 115 μm. is there. Therefore, the optical distance from the input / output optical fiber group 64 to the lens array 65 is 115 μm, and the optical distance from the lens array 65 to the MEMS mirror array 66 is 530 μm in thickness of the lens array 65 and 115 μm in the air. The sum is 968 μm.
[0107]
As the mask pattern for the upper MEMS mirror array 66 and the mask pattern for the lower drive electrode substrate in this embodiment, either one shown in FIG. 24 or FIG. 25 is used. In FIG. 24, 66a is a mirror, 66b is a torsion spring, 66c is a drive electrode, 66d is a pad electrode, 66e is a mirror, 66f is a torsion spring, 66g is a drive electrode, and 66h is a pad electrode.
[0108]
The manufacturing method of the MEMS mirror array 66 is as follows. Third reference example Since it is the same as the method described in, it is omitted here.
[0109]
FIG. 26 shows the relationship between the rotation angle and the attenuation rate in this embodiment for two cases, when the focal length of the lens array 65 is 115 μm and when it is 700 μm. Since the optical attenuation method is the same as the first prior art, the dependency of the attenuation rate on the rotation angle also exhibits the same behavior.
[0110]
< Seventh reference example >
FIG. Seventh reference example It is explanatory drawing which shows notionally the structure of the variable optical attenuator array which concerns on. The variable optical attenuator array according to this embodiment has a structure in which many variable optical attenuators based on the optical attenuation principle of the second prior art are integrated.
[0111]
As shown in FIG. 27, a variable optical attenuator array in which many variable optical attenuators according to this embodiment are integrated includes an input optical fiber group 71 composed of a plurality of optical fibers and an output optical fiber composed of a plurality of optical fibers. A group 72, a glass spacer 77, a lens array 75 in which a plurality of lenses having a focal length f are arranged in parallel, a MEMS array 76 which is a rotationally driven mirror array installed at a certain distance in the air, and a MEMS electrode 79.
[0112]
Here, when the focal length f of the lens array 75 is 700 μm, the thickness of the glass spacer 77 is 467 μm, the thickness of the lens array 75 is 530 μm, and the thickness of the substrate of the MEMS mirror array 76 is 115 μm. It is. Therefore, the optical distance from the input and output optical fiber groups 71 and 72 to the lens array 75 is 700 μm, which is a distance obtained by multiplying the thickness of the spacer 77 by 467 μm and the refractive index 1.5, and the lens array 75 to the MEMS mirror array. The optical distance up to 76 is 968 μm, which is the sum of the distance 795 μm obtained by multiplying the thickness 530 μm of the lens array 75 by the refractive index 1.5 and the distance 115 μm in the air.
[0113]
here, This form As shown in FIG. 28, the mask pattern for the upper MEMS mirror array 76 and the mask pattern for the lower drive electrode substrate in FIG. In the figure, 76a is a mirror, 76b is a torsion spring, 76c is a drive electrode, and 76d is a pad electrode.
[0114]
The manufacturing method of the MEMS mirror array 76 according to this embodiment is as follows. Third reference example Since it is the same as the method described in, it is omitted here.
[0115]
FIG. 29 shows the relationship between the rotation angle and the attenuation rate in this embodiment for two cases, when the focal length of the lens array 75 is 115 μm and when it is 700 μm. Since the optical attenuation method is the same as the second prior art, the dependency of the attenuation rate on the rotation angle also exhibits the same behavior.
[0116]
< Eighth reference example >
Figure 30 Eighth reference example It is explanatory drawing which shows notionally the structure of the variable optical attenuator array which concerns on. The variable optical attenuator array according to this embodiment includes an input optical fiber 81, an output optical fiber 82, a circulator 83, an input / output optical fiber 84, a waveguide substrate 85, Third to sixth reference examples A variable optical attenuator array 86 that performs optical attenuation by the method described in the above section. The waveguide substrate 85 includes an input / output waveguide 85a and a demultiplexing / multiplexing array waveguide diffraction grating (AWG: Arrayed Waveguide Grating). ) 85b, an optical waveguide group 85c for connecting the demultiplexing / multiplexing AWG 85b and the variable optical attenuator array 86 is formed. All of these elements are fixed in contact with each other, and the alignment does not shift even with external impacts.
[0117]
In the variable optical attenuator array according to this embodiment, input light composed of a plurality of wavelengths (λ1,... ΛN) is input from the input optical fiber 81. This light enters the demultiplexing / multiplexing AWG 85b via the circulator 83, the input / output optical fiber 84, and the input / output waveguide 85a. The input light is separated for each wavelength by the demultiplexing / multiplexing AWG 85b and output to different channels (Ch1,..., ChN).
[0118]
By passing through the variable optical attenuator array 86 from the optical waveguide group 85c, each channel is attenuated independently. It returns to the demultiplexing / multiplexing AWG 85b again via the optical waveguide group 85c, and is multiplexed and output from the output optical fiber 82 via the input / output optical waveguide 85a, the input / output optical fiber 84, and the circulator 83. The
[0119]
According to this embodiment, input light composed of a plurality of wavelengths can be obtained as output light by performing an attenuation operation independently for each wavelength.
[0120]
<Ninth Reference Example>
FIG. Ninth reference example It is explanatory drawing which shows notionally the structure of the variable optical attenuator array which concerns on. The variable optical attenuator array according to this embodiment is Eighth reference example An output spectrum monitoring function is added to the variable optical attenuator array according to the above. That is, the variable optical attenuator according to this embodiment includes a directional coupler 95a for monitoring, an optical waveguide 95d for output light monitoring, an AWG 95b for output light monitoring, an optical waveguide group 95c for output light monitoring, The photodetector array 96 is added to the variable optical attenuator array according to the eighth reference example. Among these, the directional coupler 95a, the optical waveguide 95d, the output light monitoring AWG 95b, and the optical waveguide group 95c are installed on the same waveguide substrate 95. The directional coupler 95a is installed in the middle of the output optical waveguide 95d, and the separation ratio is A vs. (1-A) (A <1). The value of A is, for example, 0.99.
[0121]
In the variable optical attenuator array according to this embodiment, input light composed of a plurality of wavelengths (λ1... ΛN) is input from the input optical fiber 81. This light enters the demultiplexing / multiplexing AWG 85b via the circulator 83, the input / output optical fiber 84, the input / output waveguide 85a, and the directional coupler 95a. The input light is separated for each wavelength by the demultiplexing / multiplexing AWG 85b, output to different channels (Ch1,. Attenuated independently. After that, the signal returns to the demultiplexing / multiplexing AWG 85b, and is reversely combined to reach the directional coupler 95a.
[0122]
In the directional coupler 95a, A (for example, 99%) of the amount of returned light is passed through the input / output optical waveguide 85a, and (1-A) (for example, 1%) is sent to the output light monitoring AWG 95b. Send to. The demultiplexing function of the output light monitoring AWG 95b is the same as the demultiplexing / multiplexing AWG 85b. The light separated by the output light monitoring AWG 95b for each wavelength (λ1... ΛN) reaches the photodetector array 96, and the light intensity for each wavelength can be measured. Therefore, the spectrum output to the output optical fiber 82 can be monitored. As a result, it is possible to perform a light attenuation action with high accuracy. Functions other than monitoring the output spectrum Eighth reference example Is equivalent to
[0123]
< Tenth reference example >
Figure 32 Tenth reference example It is explanatory drawing which shows notionally the structure of the variable optical attenuator array which concerns on. This form Ninth reference example Is added with an input spectrum monitor function. That is, Ninth reference example On the other hand, a directional coupler 105a for input light monitoring, an optical waveguide 105d for input light monitoring, an AWG 105b for input light monitoring, an optical waveguide group 105c for input light monitoring, and light detection for input light monitoring. Is added, and the performance and specifications of the input light monitoring AWG 105b are the same as the demultiplexing / multiplexing AWG 85b and the output light monitoring AWG 95b in the ninth reference example.
[0124]
The separation ratio in the directional coupler 105a for monitoring input light is A vs. (1-A) (A <1), and the value of A is, for example, 0.99. A part (1-A) (for example, 1%) of the input light is sent to the input light monitoring AWG 105b. Since the demultiplexing function of the input light monitoring AWG 105b is the same as that of the demultiplexing / multiplexing AWG 85b, it is separated for each wavelength (λ1,..., ΛN), detected by the photodetector array 106, and input spectrum Can be monitored. This feature Ninth reference example Since both the spectrum before light attenuation and the spectrum after light attenuation can be monitored, it is possible to perform a light attenuation action with higher accuracy.
[0125]
In FIG. 32, Ninth and tenth reference examples The same numbers are assigned to the same parts as in FIG.
[0126]
< Eleventh reference example >
FIG. Eleventh reference example It is explanatory drawing which shows notionally the structure of the variable optical attenuator array which concerns on. The variable optical attenuator array according to this embodiment includes an input optical fiber 111, an output optical fiber 112, a waveguide substrate 113, Seventh reference example And a variable optical attenuator array 114 that performs optical attenuation by the method described in (1).
[0127]
The waveguide substrate 113 includes an input optical waveguide 113a, a demultiplexing AWG 113b, an input optical waveguide group 113c that connects the demultiplexing AWG 113b and the variable optical attenuator array 114, and a variable optical attenuator. An output optical waveguide group 113e that connects the array 114 and the multiplexing AWG 113d, a multiplexing AWG 113d, and an output optical waveguide 113f are formed.
[0128]
In the variable optical attenuator array according to this embodiment, input light composed of a plurality of wavelengths (λ1,..., ΛN) is input from the input optical fiber 111. This light enters the demultiplexing AWG 113b via the input optical fiber 111 and the input optical waveguide 113a. The input light is separated for each wavelength by the demultiplexing AWG 113b and output to different channels (Ch1,..., ChN).
[0129]
After that, the light is attenuated independently for each channel by passing through the variable optical attenuator array 114, multiplexed through the multiplexing AWG 113d, and output optical fiber 112 through the output optical waveguide 113f. Is output from.
[0130]
The variable optical attenuator array according to this embodiment can attenuate the light intensity independently for each wavelength. In addition, all these elements are fixed in contact with each other, so that the alignment does not shift even with an external impact or the like.
[0131]
< Twelfth reference example >
FIG. Twelfth reference example It is explanatory drawing which shows notionally the structure of the variable optical attenuator array which concerns on. The variable optical attenuator array according to this embodiment is Eleventh reference example Is added with an output spectrum monitor function.
[0132]
That is, the variable optical attenuator array according to this embodiment is Eleventh reference example On the other hand, a directional coupler 123a for output light monitoring, an optical waveguide 123d for output light monitoring, an output light monitoring AWG 123b having the same demultiplexing function as the demultiplexing AWG 113b and the multiplexing AWG 113d, The optical waveguide group 123c for output monitoring is added to the same optical waveguide substrate 123 and formed. The directional coupler 123a is installed in the middle part of the optical waveguide 123d, and the separation ratio in the directional coupler 123a is A vs. (1-A) (A <1). 99. The light demultiplexed in the output light monitoring AWG 123b is incident on the output light monitoring photodetector array 126 via the output light monitoring optical waveguide group 123c, and is detected for each channel.
[0133]
According to the variable optical attenuator array of the present embodiment, the light intensity can be attenuated independently for each wavelength, and the output spectrum can be monitored, so that a highly accurate optical attenuation operation can be performed. In addition, all the elements are fixed in contact with each other, so that the alignment does not shift even with an external impact or the like.
[0134]
In FIG. 34, Eleventh reference example The same numbers are assigned to the same parts as in FIG.
[0135]
< 13th reference example >
FIG. 13th reference example It is explanatory drawing which shows notionally the structure of the variable optical attenuator array which concerns on. The variable optical attenuator array according to this embodiment is Twelfth reference example Is added with an input spectrum monitor function.
[0136]
That is, the variable optical attenuator array according to this embodiment is Twelfth reference example On the other hand, a directional coupler 133a for input light monitoring, an optical waveguide 133d for input light monitoring, an input light monitoring AWG 133b having the same demultiplexing function as the demultiplexing AWG 113b, and the like, The optical waveguide group 133c is additionally formed on the same optical waveguide substrate 133. The directional coupler 133a for monitoring input light is installed in the middle part of the optical waveguide 133d, and the separation ratio in the directional coupler 133a is A vs. (1-A) (A <1). The value of A is, for example, 0.99. The light demultiplexed by the input light monitoring AWG 133b is incident on the input light monitoring photodetector array 136 via the optical waveguide group 133c for input light monitoring, and is detected for each channel.
[0137]
According to the variable attenuator array according to the present embodiment, the light intensity can be attenuated independently for each wavelength, and both the spectrum before and after the light attenuation can be monitored, so that the light attenuation action with higher accuracy can be achieved. It can be performed. In addition, all the elements are fixed in contact with each other, so that the alignment does not shift even with an external impact or the like.
[0138]
In FIG. 35, Eleventh and twelfth reference examples The same numbers are assigned to the same parts as in FIG.
[0139]
【The invention's effect】
As described above in detail with the embodiment, according to the present invention, the light that is not affected by the bending of the reflecting mirror, can be driven at a high speed, and the fine adjustment of position during the manufacturing is reduced. An attenuator can be realized. Further, it is possible to realize an optical attenuator array that is small and consumes less power.
[0140]
[Brief description of the drawings]
[Figure 1] First reference example It is explanatory drawing which shows notionally the structure of the variable optical attenuator which concerns on.
[Figure 2] First reference example It is a characteristic view which shows the rotation angle dependence of the optical attenuation factor in the variable optical attenuator concerning.
[Fig. 3] Second reference example It is explanatory drawing which shows notionally the structure of the variable optical attenuator which concerns on.
[Fig. 4] Second reference example It is a characteristic view which shows the rotation angle dependence of the optical attenuation factor in the variable optical attenuator concerning.
[Figure 5] Embodiment of the present invention It is explanatory drawing which shows notionally the structure of the variable optical attenuator which concerns on.
[Fig. 6] Embodiment of the present invention It is a characteristic view which shows the translation distance dependence of the optical attenuation factor in the variable optical attenuator concerning.
[Fig. 7] Third reference example It is explanatory drawing which shows notionally the structure of the variable optical attenuator array which concerns on.
[Fig. 8] Third reference example It is a figure which shows the lens array in the variable optical attenuator array which concerns on this, (a) is the top view, (b) is the side view.
FIG. 9 Third reference example It is a figure which shows the MEMS mirror array in the variable optical attenuator array which concerns on this, (a) is the perspective view, (b) is the A sectional drawing, (c) is the B sectional drawing.
FIG. 10 Third reference example It is a top view which shows the upper MEMS mirror array board | substrate in the variable optical attenuator array which concerns on.
FIG. 11 Third reference example It is a top view which shows the lower MEMS drive electrode board | substrate in the variable optical attenuator array which concerns on.
FIG. Third reference example 4A and 4B are views showing an upper MEMS mirror array mask in the variable optical attenuator array according to the first embodiment, wherein FIG. 4A is a top view showing a substrate-side etching pattern, and FIG. 4B is a top view showing a mirror and a spring portion forming pattern.
FIG. 13 Third reference example It is explanatory drawing which shows the preparation process of the upper MEMS mirror array in the variable optical attenuator array which concerns on.
FIG. 14 Third reference example 4A and 4B are diagrams showing a lower MEMS drive electrode substrate mask in the variable optical attenuator array according to FIG. 5A, a top view showing a mask for forming an electrode forming pattern, and FIG. 5B showing a mask for engraving by anisotropic etching. It is a top view.
FIG. 15 Third reference example It is explanatory drawing which shows the lower MEMS drive electrode board | substrate production process in the variable optical attenuator array which concerns on.
FIG. 16 Third reference example It is explanatory drawing of the variable optical attenuator array of the horizontal rotation which concerns on.
FIG. 17 is an explanatory diagram showing a laterally rotating electrode pattern of a variable optical attenuator array according to a third reference example.
FIG. 18 Fourth reference example It is explanatory drawing which shows notionally the structure of the variable optical attenuator array which concerns on.
FIG. 19 Fourth reference example It is a characteristic view which shows the rotation angle dependence of the attenuation factor in the variable optical attenuator array concerning.
FIG. 20 Fifth reference example It is explanatory drawing which shows notionally the structure of the variable optical attenuator array which concerns on.
FIG. 21 Fifth reference example It is explanatory drawing which shows the mask pattern of the upper MEMS mirror array and lower drive electrode board | substrate in the variable optical attenuator array which concerns on.
FIG. 22 Fifth reference example It is a characteristic view which shows the translation movement distance dependence of the attenuation factor which concerns on.
FIG. 23 Sixth reference example It is explanatory drawing which shows notionally the structure of the variable optical attenuator array which concerns on.
FIG. 24 Sixth reference example It is explanatory drawing which shows the 1st mask pattern of the upper MEMS mirror array and lower drive electrode board | substrate in the variable optical attenuator array which concerns on.
FIG. 25 Sixth reference example It is explanatory drawing which shows the 2nd mask pattern of the upper MEMS mirror array and lower drive electrode board | substrate in the variable optical attenuator array which concerns on.
FIG. 26 Sixth reference example It is a characteristic view which shows the rotation angle dependence of the attenuation factor in the variable optical attenuator array concerning.
FIG. 27 Seventh reference example It is explanatory drawing which shows notionally the structure of the variable optical attenuator array which concerns on.
FIG. 28 Seventh reference example It is explanatory drawing which shows the pattern of the lower drive electrode board | substrate in the variable optical attenuator array which concerns on.
FIG. 29 Seventh reference example It is explanatory drawing which shows the rotation angle dependence of the attenuation factor in the variable optical attenuator array which concerns on.
FIG. 30 Eighth reference example It is explanatory drawing which shows notionally the structure of the variable optical attenuator array which concerns on.
FIG. 31 Ninth reference example It is explanatory drawing which shows notionally the structure of the variable optical attenuator array which concerns on.
FIG. 32 Tenth reference example It is explanatory drawing which shows notionally the structure of the variable optical attenuator array which concerns on.
FIG. 33 Eleventh reference example It is explanatory drawing which shows notionally the structure of the variable optical attenuator array which concerns on.
FIG. 34 Twelfth reference example It is explanatory drawing which shows notionally the structure of the variable optical attenuator array which concerns on.
FIG. 35 13th reference example It is explanatory drawing which shows notionally the structure of the variable optical attenuator array which concerns on.
FIG. 36 is an explanatory diagram conceptually showing a variable optical attenuator according to the first conventional technique.
FIG. 37 is an explanatory diagram conceptually showing a variable optical attenuator according to a second conventional technique.
FIG. 38 is a characteristic diagram showing the relationship between the rotation angle of the rotary drive mirror and the light attenuation rate in the variable optical attenuator according to the second prior art.
FIG. 39 is an explanatory diagram conceptually showing a variable optical attenuator array according to a third conventional technique.
FIG. 40 is an explanatory diagram conceptually showing a variable optical attenuator according to a fourth conventional technique.
FIG. 41 is a characteristic diagram showing the relationship between the temperature difference and the relative intensity of light at the output port in the variable optical attenuator according to the fourth prior art.
FIG. 42 is a conceptual diagram showing a variable optical attenuator according to a fifth prior art.
FIG. 43 is a conceptual diagram showing a variable optical attenuator according to a sixth prior art.
[Explanation of symbols]
1, 11, 21, 81, 111 Input optical fiber
2, 12, 22, 82, 112 Output optical fiber
3, 13, 23, 83 Circulator
4, 14, 24, 84 Input / output combined optical fiber
5, 15, 17, 25, 27 Lens
6, 16 Rotating mirror
26 Translational drive mirror
31, 41, 51, 61, 71 Input optical fiber group
32, 42, 52, 62, 72 Output optical fiber group

Claims (1)

An input optical fiber, an output optical fiber, a circulator, an input / output optical fiber, a first lens having a first focal length f1, a second lens having a second focal length f2, and a translation drive In a variable optical attenuator with possible translation drive mirrors,
The distance from the end face of the input / output optical fiber to the first lens is f1, and the distance from the first lens to the second lens is f1 + f2, from the second lens to the translation drive mirror. The distance is f2, and the focal point is placed on the mirror surface of the translation drive mirror.
Light radiated from the end face of the input / output optical fiber via the input optical fiber and the circulator is reflected on the mirror surface of the translation drive mirror via the first lens and the second lens. Then, the optical path is again formed so as to return to the end face of the input / output optical fiber via the second lens and the first lens, and again toward the output optical fiber via the circulator. on the other hand,
By driving the translation drive mirror in translation, the coupling efficiency of the return light at the end face of the input / output optical fiber to the input / output optical fiber is changed, and the output with respect to the intensity of light from the input optical fiber is changed. A variable optical attenuator for controlling an attenuation rate of light intensity in an optical fiber for use.

Images