JP2009175633A - Optical signal processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the following problems: in an optical signal processor such as a wavelength blocker, a wavelength selective switch, and a variable dispersion compensator, a passband and signal processing bandwidth of each wavelength channel are wide, so that it is difficult to accurately detect and adjust a shift of a center wavelength of the passband so as to adjust the position of liquid crystal elements or the like by optical power meter measurements; and in a process of manufacturing and adjusting the optical signal processor, it takes measurement time to perform position adjustment using an optical spectrum analyzer, thereby hindering automation of the adjustment. <P>SOLUTION: The optical signal processor includes a narrow positioning mark on a signal processing element for modulating the optical signal. The light power of a test optical signal that passes through the positioning mark is detected to adjust the position of the signal processor element. It is preferable that the width of an electrode of the positioning mark is equal to or smaller than the beam diameter of the test optical signal. The positioning mark may have the same structure as that of elements and may be a mask that shields the optical signal. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical signal processing device. More specifically, the present invention relates to a signal processing element used in an optical signal processing apparatus including a spatial optical signal system.

  As the speed and capacity of optical communication networks have increased, there has been an increasing need for optical signal processing apparatuses such as those represented by processing of wavelength division multiplexing (WDM) transmission signals. For example, there is a demand for a function of switching the path of multiplexed optical signals between nodes. An optical signal processing apparatus has been increased in speed by performing path conversion without changing the optical-electrical conversion.

  On the other hand, from the viewpoint of miniaturization and integration of signal processing devices, research and development of waveguide type optical circuits (PLCs) are in progress. In the PLC, for example, a core made of quartz glass is formed on a silicon substrate and various functions are integrated in one chip, and an optical functional device with low loss and high reliability is realized. Furthermore, a composite optical signal processing component (apparatus) that combines a plurality of PLC chips and other optical functional components has also appeared.

  For example, Patent Document 1 discloses an optical signal processing device in which a waveguide type optical circuit (PLC) including AWG or the like and a spatial modulation element such as a liquid crystal element are combined. More specifically, a wavelength blocker including a PLC and a collimating lens arranged symmetrically with respect to the liquid crystal element, a wavelength equalizer, a dispersion compensator, and the like are being studied. In these optical signal processing devices, optical signal processing is performed independently for each wavelength for a plurality of optical signals having different wavelengths.

  FIG. 7 is a conceptual diagram illustrating an example of an optical signal processing device. In this optical signal processing apparatus, an optical signal is input / output via the spectroscopic element 51. The spectroscopic element 51 demultiplexes a plurality of optical signals having different wavelengths at an emission angle θ corresponding to the wavelengths. The demultiplexed optical signal is emitted toward the condenser lens 52. The optical signal condensed by the condenser lens 52 is condensed at predetermined positions on the signal processing element 53 having a function of intensity modulation, phase modulation or deflection corresponding to the emission angle θ. That is, it should be noted that the optical signal is collected at different positions of the signal processing element according to the wavelength of the input optical signal. The signal processing element 53 is, for example, a liquid crystal element composed of a plurality of element elements (pixels). By controlling the transmittance of each element, the optical signal of each wavelength is subjected to intensity modulation and the like, and a predetermined signal processing function is realized for each wavelength. The signal-processed optical signal is reflected by the mirror 54, reverses the traveling direction, passes through the condenser lens 53 again, and is multiplexed in the spectroscopic element 51. The combined optical signals of the respective wavelengths are output to the outside of the optical signal processing apparatus again as output light.

  In FIG. 7, the spectroscopic element 51 is conceptually shown as long as it can demultiplex and multiplex optical signals according to the wavelength. For example, there are a grating, a prism, and an arrayed waveguide grating (AWG). The signal processing element only needs to be capable of modulating the intensity or phase of the optical signal, or the intensity and phase, or capable of deflecting the traveling direction of the optical signal. For example, there are a liquid crystal element, a MEMS (Micro Electro Mechanical Systems) mirror, a non-linear crystal, and the like.

  The optical signal processing device shown in FIG. 7 is configured to perform both demultiplexing and multiplexing of the optical signal by one spectroscopic element by folding the optical signal using a mirror. This configuration is generally called a reflection type. Optical signal processing such as wavelength blocking is not limited to this configuration. For example, without using a mirror, the signal processing element shown in FIG. 7 is positioned on the axis of symmetry, and the output system is composed of another lens and a spectroscopic element on the opposite side of the incident system on the extension line of the incident light optical axis. It is also possible to have a configuration in which This configuration is a configuration that performs demultiplexing and multiplexing of optical signals via independent incident and outgoing systems, respectively, and is called a transmission type. Furthermore, in the apparatus configuration shown in FIG. 7, it is also possible to combine the optical signals by changing the direction of the mirror and using an emission system composed of another lens and a spectroscopic element arranged at an arbitrary position. . For example, it is also possible to configure the exit system with a lens and a spectroscopic element arranged in a direction perpendicular to the incident optical path with the mirror reflecting surface inclined by 45 degrees with respect to the incident optical path of the optical signal. Further, when the signal processing element has a deflection function, a plurality of emission systems can be provided.

  In FIG. 7, the spectroscopic element 51 and the condensing lens 52 are arranged apart from each other by a front focal length FFL, and the signal processing element 53 and the condensing lens 52 are arranged apart from each other by a rear focal length BFL. The focal point of the light collected by the condenser lens 52 must be on the surface of the mirror 54 at all wavelengths used. When deviating from the mirror surface, there arises a problem of causing a coupling loss between input and output light. At the same time, since the beam spot diameter of the collected optical signal on the signal processing element surface is increased, there arises a problem that the wavelength resolution is lowered.

  Further, the signal processing element 53 needs to have a spatially periodic structure so that it can selectively modulate for each wavelength of the optical signal. For example, when the signal processing element 53 is a liquid crystal element, the structure of a plurality of element elements in the liquid crystal element must be designed in accordance with the optical characteristics of the spectroscopic element and the condenser lens.

  More specifically, it is known that the wavelength dependence of the condensing position on the signal processing element follows the product of the angular dispersion value of the spectroscopic element and the focal length of the condensing lens. The wavelength dependence of the light collection position is also called a linear dispersion value of the spectroscopic optical system. The linear dispersion value of the optical system determined by the spectroscopic element and the condensing lens needs to be sufficiently coincident with the linear dispersion value used for designing the structure of the signal processing element. If there is a deviation between these linear dispersion values, the actual focal point position of the optical signal will not coincide with the position of the individual element elements (for example, pixels of the liquid crystal shutter element) of the signal processing element. Due to this mismatch, an error occurs in the wavelength of the optical signal actually processed. Next, the wavelength dependence of the condensing position on the signal processing element will be described in more detail using a liquid crystal element as an example.

Japanese Patent Laid-Open No. 2002-250828 (pages 16, 19, 20, 20, 27, 29D, etc.) ITU Recommendation G. 694.1

  FIG. 8 is a diagram showing a more specific configuration of an optical signal processing device using AWG. In FIG. 7, the AWG 56 is used as the spectroscopic element, and the liquid crystal element 53 is used as the signal processing element. A cylindrical lens 57 is disposed in the vicinity of the emission end 58 of the AWG 56. The cylindrical lens 57 condenses the optical signal in the direction perpendicular to the AWG spectral plane (xz plane), that is, in the thickness direction of the AWG substrate. The liquid crystal element 53 has a structure in which a plurality of element elements are arranged in the x direction.

  The AWG 56 is emitted to the spatial optical system at an emission angle θ with respect to the main optical axis from the emission end 58 in the z direction according to the wavelength of the optical signal. The optical signal is condensed on a predetermined element of the liquid crystal element 53 corresponding to the emission angle θ. As described above, the linear dispersion value of the optical system determined by the AWG 56 and the condensing lens 52 needs to be sufficiently coincident with the linear dispersion value used for designing the element element structure of the liquid crystal element 53. . If there is a deviation between these linear dispersion values, the actual focal point position of the optical signal will not coincide with the position of each element element. This mismatch causes an error in the wavelength of the optical signal actually processed. Therefore, in the manufacturing process of the optical signal processing device, it is necessary to adjust the actual focal point position of the optical signal and the position of each corresponding element.

  9a and 9b are diagrams for explaining the correspondence between the structure of the element element of the liquid crystal element and the transmission band of the communication band. As shown in FIG. 9a, the liquid crystal element 1 has a configuration in which a plurality of element elements 2a, 2b,... 2n are arranged in one direction (x-axis). The light transmittance of each element is controlled by a control signal supplied to the liquid crystal element 1, and the intensity of the optical signal transmitted through one element is modulated. The electrode width d in the arrangement direction (x-axis) of one element element is determined according to the communication wavelength bandwidth to be processed. The x direction in FIG. 9a corresponds to the x direction in FIG. In FIG. 9a, the number of element elements is determined by the number of channels of the communication system handled by the optical signal processing apparatus. Further, the electrode width d may be a constant value, or may be different for each element element depending on the design of the communication system and the optical system.

  In the optical communication field, individual communication channels are generally arranged at equal frequency intervals or equal wavelength intervals. For example, as disclosed in Non-Patent Document 1, in a C-band and L-band DWDM communication system, individual communication channels are arranged at fixed frequency intervals (12.5, 25, 50, 100 GHz). It is prescribed as follows. A channel arrangement configuration in which individual communication channels are arranged at equal frequency intervals or equal wavelength intervals is also called a communication wavelength grid having equal frequency intervals or equal wavelength intervals.

  FIG. 9b is a diagram showing a transmission band in a communication wavelength grid with equal wavelength intervals. The horizontal axis indicates the wavelength of the optical signal, and the vertical axis indicates the light transmittance of the optical signal transmitted through the element element. Corresponding to one element element 2a, one transmission band 3a is formed on the wavelength axis. The transmission band 3a has a bandwidth corresponding to the electrode width of the element element 2a. A plurality of transmission bands 3a, 3b,... 3n are arranged on the wavelength axis corresponding to the plurality of element elements.

  Optical signal processing devices such as wavelength blockers, wavelength selective switches, and tunable dispersion compensators are characterized by a wide transmission band and signal processing band for each wavelength channel. This is because the electrode width in the x direction of the element element and the bandwidth of each wavelength channel corresponding to each element element are substantially proportional, so that a wide bandwidth can be obtained simply by forming the electrode width wide. For example, in FIG. 9b, adjacent transmission bands 3a and 3b are arranged while overlapping attenuation bands 9 in which the light transmittance abruptly attenuates according to the communication system design specifications. Focusing on one transmission band, the light transmittance becomes the minimum value in a far wider wavelength range compared to the beam width of the unmodulated optical signal, and one transmission band has a flat transmission characteristic at this minimum value. . When trying to adjust the element element position of a liquid crystal element having a very wide signal processing band for each channel, the following problems arise.

  10a and 10b are diagrams for explaining the detected light power level of the test light signal that passes through the element element. In order to process an optical signal in a desired wavelength range for one element element, the actual position of the liquid crystal element in the optical signal processing apparatus is set in the x-axis direction using the test optical signal. It is necessary to adjust with. Alternatively, in order to change the emission direction of the optical signal from the AWG, it is necessary to rotate the AWG within the demultiplexing plane (in the xz plane) and adjust the direction in which the AWG is installed.

  Furthermore, in order to make the element elements located at both ends of the liquid crystal element coincide with the corresponding channel of the communication band, it is necessary to correct the error of the linear dispersion value of the optical system for the entire span on the wavelength axis. When adjusting the entire span on the wavelength axis, it is necessary to adjust the focal length of the condenser lens. In any of the adjustments, a test optical signal having a basic wavelength is transmitted through the element element, the light transmittance is measured, the positional deviation of the liquid crystal element is detected, and the position adjustment is performed. Here, the test optical signal refers to an optical signal whose wavelength is accurately known and can be used as a reference when performing wavelength adjustment of the optical signal processing apparatus.

  However, as shown in FIG. 10a, since the light transmittance is constant with respect to the wavelength change of the test optical signal, there is a dead area 5 in which the positional deviation cannot be detected. In the insensitive region 5 near the center wavelength of the transmission band 3 where position adjustment is to be performed, the detected light power level of the optical power meter is flat and does not fluctuate. That is, the positional deviation cannot be recognized unless the wavelength of the test optical signal is the wavelength of the inclined attenuation region 9 at both ends of the transmission band where the transmission characteristics fluctuate. In the manufacturing process of the optical signal processing apparatus, it is preferable to measure the transmittance of the test optical signal with an optical power meter because of the demand for simplicity of measurement. FIG. 10b shows the relationship between the wavelength of the test optical signal and the optical power detected by the optical power meter for one transmission band. The horizontal axis of FIG. 10b is equivalent to the wavelength error caused by the x-axis position error of the signal processing element. In the measurement by the optical power meter, the shift of the center wavelength of one transmission band can be accurately detected and adjusted. difficult.

  Although the transmission band characteristic can be measured by an optical spectrum analyzer, it takes time to measure the optical spectrum analyzer. As described above, the transmission band and signal processing band of one channel are wide. Further, when the optical spectrum analyzer measurement is performed in the measurement resolution band necessary for detecting the positional deviation in the total transmission band of all the communication channels handled by the liquid crystal element, the number of measurement points is very large and the sweep time is long. In the manufacturing and adjustment process of the optical signal processing apparatus, there are problems of measurement time and difficulty in automation of measurement adjustment in order to adjust the position of the liquid crystal element using an optical spectrum analyzer. Further, the optical spectrum analyzer is more expensive than the optical power meter, and there has been a demand for measuring the test optical signal and adjusting the position of the liquid crystal element in a short time by using a cheaper optical power meter.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a signal processing element and an optical signal processing having a configuration capable of easily adjusting the position of the signal processing element of the optical signal processing device. It is to provide a method for adjusting an apparatus.

  In order to achieve such an object, the present invention according to claim 1 divides an optical signal into a plurality of optical signals having different wavelengths and separates the optical signals of the respective wavelengths. An optical signal processing apparatus that performs processing, and that splits a plurality of optical signals having different wavelengths with an emission angle corresponding to the wavelength of the optical signal, and condenses the optical signal emitted from the spectral means Condensing means and signal processing means for modulating the collected optical signal, wherein the signal processing means corresponds to the optical signal of each wavelength and is formed by signal light from the spectroscopic means. A plurality of signal processing element elements arranged in a direction intersecting with the surface, and the width of the at least one adjustment signal processing element element among the plurality of signal processing element elements is the signal processing The one of the split optical signals on the means When the line direction beam diameter as Wx, an optical signal processing apparatus characterized by comprising a or less 1.5Wx.

  A second aspect of the present invention is the optical signal processing apparatus according to the first aspect, wherein a width of the at least one adjustment signal processing element element in a direction perpendicular to the intersecting line is the one light that is dispersed. If the beam diameter in the direction perpendicular to the intersecting line of signals is Wy, it is 1.5 Wy or less.

  A third aspect of the present invention is the optical signal processing device according to the first or second aspect, wherein the adjustment signal processing element elements are located at both ends of the plurality of signal processing element elements.

  A fourth aspect of the present invention is the optical signal processing device according to any one of the first to third aspects, wherein the width of the adjustment signal processing element element in the intersecting direction is in the range of 0.5 Wx to 1.0 Wx. It is characterized by that.

  A fifth aspect of the present invention is the optical signal processing device according to any one of the first to fourth aspects, wherein the signal processing means is a liquid crystal element having a liquid crystal element element as a signal processing element element, and the adjustment signal The processing element element is composed of a liquid crystal element element having the same configuration as the element element.

  A sixth aspect of the present invention is the optical signal processing device according to any one of the first to fourth aspects, wherein the signal processing means is a liquid crystal element having a liquid crystal element element as a signal processing element element, and The signal processing element element is constituted by a mask that blocks an optical signal.

  The invention according to claim 7 is a spectroscopic unit that splits a plurality of optical signals having different wavelengths at an emission angle corresponding to the wavelength of the optical signal, and a condensing unit that condenses the optical signal output from the spectroscopic unit. A plurality of signal processing element elements arranged in a direction intersecting with the spectral plane formed by the signal light from the spectroscopic means corresponding to the optical signals of the respective wavelengths, and modulating the collected optical signal An optical signal processing apparatus for performing signal processing on optical signals having different wavelengths, wherein the position of the signal processing means is adjusted from a test optical signal light source. Supplying a test optical signal so as to pass through at least one adjustment signal processing element element of the plurality of signal processing element elements, wherein the adjustment signal processing element element in the direction of the intersecting line is supplied. The width is The test that is 1.5 Wx or less, and that passes through the at least one adjustment signal processing element element, where Wx is the beam diameter in the crosswise direction of the one split optical signal on the processing means. Measuring the output intensity of the optical signal; and the position of the signal processing means in the intersecting direction or the effective focus of the light collecting means so that the measured output intensity of the test optical signal is maximized or minimized. And adjusting the distance. The invention is an invention of an adjustment method for an optical signal processing device.

  The invention according to claim 8 is the adjustment method of the optical signal processing device according to claim 7, wherein a width of the at least one adjustment signal processing element element in a direction perpendicular to the intersecting line is the spectrally separated. When the beam diameter of one optical signal in the direction perpendicular to the intersecting line is Wy, the output intensity of the test optical signal that is 1.5 Wy or less and passes through the at least one adjustment signal processing element is maximum or The position of the signal processing means is further adjusted so that the position of the signal processing means in the direction perpendicular to the intersecting line or the main optical path of the optical signal is a rotation axis so as to be minimized. .

  The invention of claim 9 is the adjustment method of the optical signal processing device according to claim 7 or 8, wherein the adjustment signal processing element elements are located at both ends of the plurality of signal processing element elements. And

  A tenth aspect of the present invention is the method of adjusting an optical signal processing device according to any one of the seventh to ninth aspects, wherein the width of the adjustment signal processing element element in the intersecting direction is from 0.5 Wx to 1. It is in the range of .0Wx.

  Preferably, in the adjustment method for an optical signal processing device according to any one of claims 7 to 10, the signal processing means is a liquid crystal element having a liquid crystal element element as a signal processing element element, and the adjustment signal processing element element is used. Can be composed of a liquid crystal element having the same structure as the element.

  Preferably, in the adjustment method for an optical signal processing device according to any one of claims 7 to 10, the signal processing means is a liquid crystal element having a liquid crystal element element as a signal processing element element, and the adjustment signal processing element element is used. Can be configured with a mask that blocks an optical signal.

  As described above, according to the present invention, it is possible to easily adjust the position of the signal processing element of the optical signal processing device. Using an inexpensive optical power meter, the element element position of the signal processing element can be adjusted so that an optical signal having a desired wavelength is processed by a simple measurement adjustment system configuration.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The optical signal processing device of the present invention is characterized in that a signal processing element that modulates an optical signal is provided with a narrow position adjustment mark. The optical power level of the test optical signal transmitted through the position adjustment mark and the vicinity thereof is detected to detect a positional shift and adjust the position of the signal processing element. The width of the position adjustment mark is preferably about the beam diameter of the test optical signal. In the signal processing element, individual element elements are arranged along an axis included in the spectral plane of the spectroscopic element. Each element element performs signal processing of the optical signal demultiplexed for each wavelength in the spectroscopic element. The position adjustment mark has the same configuration as the element element, and may have a signal processing function of an optical signal, or may be a mask that blocks the optical signal. Specific examples of signal processing elements include, but are not limited to, liquid crystal elements and MEMS. Specifically, the optical signal processing apparatus can be applied to wavelength blockers, wavelength selective switches, gain equalizers, dispersion compensators, optical signal synthesizers, and the like.

  FIG. 1a is a diagram showing a configuration of a position adjustment mark of a signal processing element in an optical signal processing device of the present invention. This signal processing element 1 is located at both ends of the element element group on the x-axis in addition to a plurality of element elements 2 that perform signal processing on a normal optical signal, and is used for adjustment marks 6a that are not used for signal processing. There is a feature in having 6b. The x-axis is an axis including the demultiplexing surface of a spectroscopic element such as an AWG, and the optical signal is condensed on the element element at a predetermined position according to the wavelength (channel) of the optical signal. The adjustment marks 6a and 6b have the same configuration and signal processing function as the element element 2, and can modulate the intensity of the optical signal. For example, in the case of a liquid crystal element, the position adjustment mark has the same configuration as the liquid crystal pixel, and can be easily formed simultaneously with the manufacture of the liquid crystal element. The present invention is characterized in that the width of the adjustment marks 6a and 6b in the x-axis direction is very narrow so as to be equal to or smaller than the beam diameter of the test optical signal used when adjusting the position of the signal processing element. If a MEMS mirror having a sufficiently narrow width can be formed, the present invention can be applied even when the signal processing element is a MEMS.

FIG. 1B is a diagram for explaining the relationship between the adjustment mark and the light transmittance of the test light signal. Since the width d _X of the adjustment marks 6a and 6b is about the beam diameter of the test optical signal, for example, the light transmittance of the optical signal transmitted through the adjustment mark shows a clear peak shape as shown in FIG. 1b. It does not have a flat transmission characteristic as in the case of transmitting through a normal element. Therefore, it is possible to easily align the signal processing element at a position where the transmitted light of the test light signal condensed near the position adjustment mark is maximized. Here, the beam diameter of the test optical signal refers to the beam diameter when the light intensity is 1 / e ^{2 of the} peak value. Next, the relationship between the beam diameter of the test optical signal and the width of the position adjustment mark will be described.

  FIG. 2 is a diagram showing the wavelength error dependence characteristics of the test optical signal transmittance that passes through the position adjustment mark of the present invention. In the reflection type wavelength blocker using the liquid crystal element having the structure shown in FIG. 1 as the signal processing element, the test optical signal appearing at the output of the AWG after passing through one of the position adjustment marks indicates the optical power level. It is a thing. The vertical axis shows the normalized transmittance (dB) based on the optical power level when the test light signal is completely transmitted through the liquid crystal element.

The test light signal and the conditions of the spectroscopic system and the condensing system are as follows. The beam diameter wo of the test optical signal is 30 μm. The linear dispersion value of the spectroscopic system and the condensing system is 120 μm / nm, and the width of each signal processing pixel is about 100 μm. The width d _{X in} the x direction of the position adjustment mark is changed to 0.5 wo (15 μm), wo (30 μm), 1.5 wo (45 μm), and 2.0 wo (60 μm).

As is clear from FIG. 2, when the width d _{X in} the x direction of the position adjustment mark is 1.5 wo or more, which is larger than the beam diameter of the test optical signal, a flat region appears at the center of the transmittance characteristic. This is because the energy of the Gaussian beam condensing spot is concentrated within 1.5 times its diameter, and corresponds to the insensitive area described with reference to FIG. On the other hand, when the width d _X is 0.5 wo smaller than the beam diameter of the test optical signal, the transmittance characteristic shows a clear peak characteristic. By using the inclined portions on both sides of this peak characteristic, the wavelength error can be detected as a change in light transmittance.

  In the C-band and L-band DWDM communication systems that are currently used as standard, the channel center wavelength has an accuracy of ± 0.01 nm, which is sufficiently smaller than the channel spacing, in order not to reduce the wavelength utilization efficiency. And the element element of the signal processing element are required to be aligned. That is, in the manufacturing / adjustment process of the optical signal processing apparatus, it is required to adjust the position of the position adjustment mark with a detection resolution of ± 0.01 nm.

  If attention is again paid to the case where the beam diameter is 1.5 wo in FIG. 2, even when the wavelength error is ± 0.01 nm, the light transmittance change amount is only 0.005 dB. Considering that a practical resolution that enables a normal optical power meter to stably measure optical power with good reproducibility is about 0.01 dB, it is necessary to detect a position adjustment mark when the beam diameter is 1.5 wo. A sufficient detection resolution of ± 0.01 nm cannot be obtained. On the other hand, when the beam diameter is wo, the light transmittance change amount increases to 0.04 dB when the wavelength error is ± 0.01 nm. Therefore, a detection resolution of ± 0.01 nm necessary for detecting the position of the position adjustment mark can be sufficiently obtained. When the beam diameter is 0.5 wo, when the wavelength error is ± 0.1 nm, the amount of change in light transmittance further increases to 0.1 dB, and further sufficient detection and decomposition necessary for position detection of the position adjustment mark is performed. can get.

  Even if the beam diameter is further narrowed to 0.5 wo or less, the sharpness of the peak shape of the transmittance characteristic does not change any more, and the transmittance is lowered and only the entire optical power level is lowered.

From the above, in order to perform position adjustment using the position adjustment mark, the width d _{X in the} X direction needs to be 1.5 wo or less with respect to the beam diameter wo, and further, approximately It is desirable to set in the range of 0.5wo to 1.0wo.

  FIG. 3 is a diagram illustrating an example of a configuration of a position adjustment system that performs position adjustment of a signal processing element including a position adjustment mark according to the present invention in a reflective optical signal processing apparatus. The optical signal processing device 13 includes a spectroscopic / condensing optical system 14 fixed on the device base, and a signal processing element 15 capable of adjusting its position. The spectroscopic / condensing optical system 14 includes a zoom condensing optical system including spectroscopic means such as AWG and a focal length variable mechanism 20. The signal processing element 15 is, for example, a liquid crystal element having the structure shown in FIG. 1, and is assumed to be integrated with a mirror in FIG.

  The focal length adjustment in the signal processing device 13 is performed by the first driving unit 16 that adjusts the focal length via the focal length variable mechanism 20, and the position adjustment of the signal processing element 15 is performed by adjusting the position of the signal processing element 15 in the x-axis direction. This is performed by the second driving means 17 for adjustment. Any of the drive means 16 and 17 can be an electric drive stage, for example. Each drive means 16 and 17 is controlled by a calculation means (for example, a personal computer) 19 including a program for performing calculation processing for adjustment.

  The second driving means 17 adjusts the position of the signal processing element 15 in the x-axis direction of FIG. That is, wavelength matching can be performed on the signal processing element. The first driving unit 16 can adjust the focal length in the spectroscopic / condensing optical system by driving the variable focal length mechanism 20. By adjusting the focal length, the linear dispersion value of the spectroscopic / condensing optical system can be adjusted. That is, it is possible to adjust the distance between two condensing points of the optical signal having the wavelengths of the both end channels in the desired wavelength band and the span width of the element elements at both ends of the signal processing element. The focal length can be adjusted by adjusting the position of the signal processing element 15 in the z direction by the second driving means 17. Therefore, the first driving means 16 and the second driving means 17 adjust the position of the signal processing element 15 in the x-axis direction and the span width of the element elements of the signal processing element 15, so that the optical signal corresponding to each channel. It is possible to make the actual condensing point and the position of each element element coincide with each other.

  The test light signal is input to the spectroscopic / condensing optical system 14 via the coupler 12 by the light sources 11a and 11b that generate test light signals having wavelengths corresponding to the positions of the position adjustment marks 6a and 6b in FIG. Is done. The test optical signal during position adjustment is input to the optical power meter 18. The measurement light power is input to the calculation means 19. The arithmetic means 19 also controls a signal processing element driving circuit 23 that generates a control signal for controlling the signal processing operation of the signal processing element 15. The light sources 11a and 11b may be sequentially switched by generating test optical signals of two types of wavelengths with one light source. The configuration of the position adjustment system shown in FIG. 3 is exemplary, and any means can be used alone, as long as the position of the signal processing element and the focal length of the spectroscopic / condensing optical system can be varied. You may use in combination. The two driving means 16 and 17 are removed from the optical signal processing apparatus 13 after the position adjustment is completed and the position of the signal processing element is fixed.

  By using the position adjustment system having the configuration shown in FIG. 3, the position of the signal processing element can be adjusted based on the detected light power level of the test light signal that passes through the position adjustment mark of the present invention. The adjustment procedure (algorithm) executed by the calculation means 19 may be any as long as it can be aligned while monitoring the level of the detection signal.

For example, wavelength matching can be performed by the following procedure.
1. The signal processing element driving circuit 23 drives the signal processing element 15 so that the test light signal from the light source 11a or the light source 11b passes through the position adjustment mark.
2. The optical power meter 18 obtains the optical power data value.
3. While the signal processing element is moved in the x-axis direction by the second driving means 17, the optical power measurement 2 is repeated several times to obtain respective optical power data values.
4). From the plurality of positions on the x-axis obtained in the procedure 3 and measured optical power data values, the x-axis position where the optical power is maximized is estimated by the computing means, and the signal processing element is moved to the estimated position.
5. Procedures 1-4 are repeated, and adjustment is terminated when the value falls within the allowable range.
The adjustment procedure described above is an exemplary method for estimating the peak value from the shape of the known peak characteristic and the actual measurement value, and determining the x-axis position that makes the measurement value of the optical power the peak value. Any other algorithm that can be used can be used. For example, there are a gradient method, a random method, and a combination thereof.

Further, the linear dispersion value of the spectroscopic optical system, that is, the span adjustment can be performed by the following procedure.
1. The signal processing element drive circuit 23 drives the signal processing element 15 so that the test light signal from the light source 11a passes through one position adjustment mark 6a.
2. The optical power data 18 is obtained by the optical power meter 18.
3. The signal processing element drive circuit 23 drives the signal processing element 15 so that the test light signal from the light source 11b passes through the other position adjustment mark 6b.
4). An optical power data value B is obtained by the optical power meter 18.
5. While moving the signal processing element 15 in the x-axis direction by the second driving means 17, steps 1-4 are repeated several times.
6). From the plurality of optical power data values A and B acquired in the procedure 5 and the x-axis position, the optimum position on the x-axis and the set amount of the focal length variable mechanism 20 set by the first driving means are determined. That is, the x-axis position of the signal processing element 15 and the focal length of the spectral / condensing optical system are set.
7). The procedure 1-6 is repeated, and if the allowable value is entered according to the set value of the procedure 6, the adjustment is finished.
The above adjustment procedure is not limited to this, and any other algorithm can be used as long as the signal processing element and the focal length can be adjusted so that the test light signal transmitted through the two adjustment markers is maximized. It may be used.

  In the position adjustment system shown in FIG. 3 described above, an example in which the focal length is mechanically adjusted via the first driving unit 16 has been shown. However, the focal length is directly adjusted by an electric signal supplied from the calculation unit 19. May be controlled. Further, a transmissive optical signal processing device may be used instead of the reflective optical signal processing device. The same adjustment method can be applied as long as the signal processing element having the position adjustment mark of the present invention having a width of 1.5 wo or less with respect to the beam diameter wo of the test optical signal is used.

  The position adjustment marks of the present invention are arranged at both ends outside the element element group as shown in FIG. 1b. However, when the span adjustment is not necessary, the position adjustment marks are arranged only in one of them. Also good. Further, it is not always necessary to be at both end positions, and when there is an unused channel or the like in the communication band of the target optical communication system, it can be arranged at a position in the element element group of the signal processing element. .

  4a and 4b are diagrams showing a signal processing element configuration including a position adjustment mark of the second embodiment in the optical signal processing apparatus of the present invention. The configuration of the signal processing element 1 shown in FIG. 4a is characterized in that the position adjustment marks 7a and 7b do not have the same configuration and signal processing function as the element elements, and are configured by a mask that blocks an optical signal. There is. In the case of a liquid crystal element, the optical signal is not completely blocked at a place other than each liquid crystal pixel 2 that is an element element, and the optical signal is transmitted to some extent. Therefore, if the position adjustment mark is formed of a mask that completely blocks the optical signal, the light transmittance of the test optical signal exhibits a peak (dip) characteristic having a minimum value as shown in FIG. 4b. This peak characteristic corresponds to an inverted version of the peak characteristic having the maximum value shown in FIG. Therefore, it is possible to adjust the position of the signal processing element with reference to the position on the x-axis where the transmittance of the test light signal is the minimum value. The position adjustment marks of the present embodiment are also arranged at both ends outside the element element group as shown in FIG. 4B. However, when the span adjustment is not necessary, the position adjustment marks may be arranged only in one of them. Further, it is not always necessary to be at both end positions, and when there is an unused channel in the central part of the communication band of the target optical communication system, it can be arranged at a position other than both ends of the signal processing element.

5a and 5b are diagrams showing a signal processing element configuration including a position adjustment mark of the third embodiment in the optical signal processing apparatus of the present invention. In this embodiment, signal alignment mark 21a of the processing element, 21b is to allow positional adjustment by the same method as the x-axis direction in the y-axis direction, the mark width d _Y in the y-axis direction in the y direction test light It is narrowed to be about the signal beam diameter. Normally, in the optical signal processing apparatus, the y direction corresponding to the thickness direction of the PLC substrate including the AWG is not related to the demultiplexing action and the formation of the optical communication channel. Accordingly, if the length in the y direction of the element element of the signal processing element is longer than the diameter of the focused beam, position adjustment may not be necessary. However, since the length of the element element in the y direction is short, if the position adjustment of the signal processing element is necessary also in the y direction, the position adjustment mark of the configuration of the present embodiment can be used for both the x axis and y axis directions. Can be adjusted independently. At this time, if the beam diameter wo _{Y in} the y-axis direction of the test light signal is used, the position adjustment mark width d _Y may be 1.5 wo _Y or less, and further, approximately in the range of 0.5 wo _Y to 1.0 wo _Y. It is preferable that

As a specific configuration of the signal processing element, for example, when the linear dispersion value of the spectral system is 120 μm / nm and the wavelength interval of one channel is 0.84 nm, the liquid crystal element has the following configuration. Each element (liquid crystal pixel) has a y-axis length of 500 μm and an x-axis length of 100 μm. When the beam diameter of the test optical signal is 250 μm and 30 μm in the y-axis and x-axis directions, respectively, the width of the position adjustment mark is y-axis width d _Y of 250 μm and x-axis width d _X of 30 μm.

  FIG. 5b shows an embodiment in which the position adjustment mark is used as a mask. The position adjustment marks in FIG. 5a are masks 22a and 22b for blocking optical signals. As in the case of the second embodiment, the position adjustment of the signal processing element can be performed with reference to the position on the x-axis and the y-axis where the transmittance of the test light signal is the lowest value.

6A and 6B are diagrams showing a driving method for position adjustment of the signal processing element. As shown in FIGS. 5a and 5b, the position adjustment marks that can be adjusted in two directions are formed, so that the signal processing elements are driven in the x-axis and y-axis directions as shown in FIG. Adjustments can be made. Further, as shown in FIG. 6b, the tilt angle θ _Z can be adjusted while being driven to rotate about the z-axis. Any adjustment algorithm may be used as long as the peak characteristic of the test light signal transmitted through the position adjustment mark can be used.

  As described above in detail, by providing the optical signal processing device with the signal processing element including the position adjustment required mark according to the present invention, the position of the signal processing element in the optical signal processing device can be easily adjusted. The position of the signal processing element can be easily adjusted so that an optical signal of the desired wavelength can be processed by the corresponding element without any coupling loss by a simple measurement adjustment system using an inexpensive optical power meter. Can do.

  The present invention can be applied to an optical signal processing device used for optical communication. It can be applied to wavelength blockers, wavelength equalizers, dispersion compensators, etc.

(A) is a figure which shows the signal processing element structure containing the position adjustment mark of 1st Example which concerns on this invention, (b) is the signal processing element containing the position adjustment mark of 1st Example which concerns on this invention It is a figure which shows the light transmittance of. It is a figure which shows the test light wavelength dependence characteristic which permeate | transmits the position adjustment mark of this invention. It is a block diagram of the position adjustment system of the signal processing element containing the position adjustment mark of this invention. (A) is a figure which shows the signal processing element structure containing the position adjustment mark of 2nd Example, (b) is a figure which shows the light transmittance of the signal processing element which concerns on a 2nd Example. (A) is a figure which shows the signal processing element structure containing the position adjustment mark of another Example, (b) is a figure which shows the light transmittance of the signal processing element which concerns on another Example. (A) is a figure explaining the drive method of a signal processing element, (b) is a figure explaining another drive method of a signal processing element. It is a notional block diagram of the conventional optical signal processing apparatus. It is a figure explaining the relationship between the output angle from a spectroscopic element, and a condensing point position. (A) is a figure explaining the relationship between the element element of a signal processing element, and a transmission band, (b) is a figure explaining the relationship between the element element of a signal processing element, and a transmission band. (A) is a figure explaining the detection light power of the test light signal which permeate | transmits an element element, (b) is a figure explaining the detection light power of the test light signal which permeate | transmits an element element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 15, 53 Signal processing element 2, 2a, 2b Liquid crystal element element 3, 3a, 3b Transmission band 4 Test optical signal 5 Dead area 6a, 6b, 7a, 7b, 21a, 21b, 22a, 22b Position adjustment mark 9 Attenuation region 11a, 11b Test light source 16, 17 Drive means 18 Power meter 20 Focal length variable mechanism 23 Signal processing element drive circuit 51 Spectroscopic element 52 Condensing lens 54 Mirror 55 Diffraction grating 56 AWG

Claims (10)

An optical signal processing device that splits an optical signal into a plurality of optical signals of different wavelengths and performs signal processing on the optical signals of each wavelength,
A spectroscopic means for splitting a plurality of optical signals having different wavelengths at an emission angle according to the wavelength of the optical signal;
Condensing means for condensing the optical signal emitted from the spectroscopic means;
Signal processing means for modulating the collected optical signal, wherein the signal processing means corresponds to the optical signal of each wavelength and intersects with a spectral plane formed by signal light from the spectral means A plurality of signal processing element elements arranged in a direction, and the width in the intersecting direction of at least one adjustment signal processing element element among the plurality of signal processing element elements is the signal processing means on the signal processing means An optical signal processing device comprising: 1.5 Wx or less, where Wx is a beam diameter in the cross direction of one optical signal that has been dispersed.   The width in the direction perpendicular to the intersecting line of the at least one adjustment signal processing element element is 1.5 Wy or less, where Wy is the beam diameter in the direction perpendicular to the intersecting line of the one dispersed optical signal. The optical signal processing apparatus according to claim 1, wherein:   The optical signal processing device according to claim 1, wherein the adjustment signal processing element elements are located at both ends of the plurality of signal processing element elements.   4. The optical signal processing device according to claim 1, wherein a width of the adjustment signal processing element element in the intersecting direction is in a range of 0.5 Wx to 1.0 Wx. 5.   The signal processing means is a liquid crystal element having a liquid crystal element as a signal processing element, and the adjustment signal processing element is composed of a liquid crystal element having the same configuration as the element. The optical signal processing apparatus according to claim 1.   5. The signal processing means is a liquid crystal element having a liquid crystal element element as a signal processing element element, and the adjustment signal processing element element is constituted by a mask for blocking an optical signal. The optical signal processing device according to any one of the above. A spectroscopic unit that splits a plurality of optical signals having different wavelengths at an emission angle corresponding to the wavelength of the optical signal, a condensing unit that collects the optical signal output from the spectroscopic unit, and an optical signal of each wavelength And a signal processing means for modulating the collected optical signal, including a plurality of signal processing element elements arranged in a direction intersecting with the spectral plane formed by the signal light from the spectroscopic means. In the optical signal processing apparatus that performs signal processing on the optical signals having the different wavelengths, the method of adjusting the position of the signal processing means,
Supplying a test light signal from a test light signal light source so as to pass through at least one of the plurality of signal processing element elements of the plurality of signal processing element elements, The width in the intersecting direction is 1.5 Wx or less, where Wx is the beam diameter in the intersecting direction of the one optical signal dispersed on the signal processing means,
Measuring the output intensity of the test light signal that is transmitted through the at least one adjustment signal processing element;
Adjusting the position of the signal processing means in the intersecting direction or the effective focal length of the light collecting means so that the measured output intensity of the test light signal is maximized or minimized. An optical signal processing device adjustment method.   The width in the direction perpendicular to the intersecting line of the at least one adjustment signal processing element element is 1.5 Wy or less, where Wy is the beam diameter in the direction perpendicular to the intersecting line of the one dispersed optical signal. The position of the signal processing means in the direction perpendicular to the intersecting line or the main of the optical signal so that the output intensity of the test optical signal transmitted through the at least one adjustment signal processing element is maximized or minimized. 8. The method of adjusting an optical signal processing device according to claim 7, further comprising adjusting an arrangement angle of the signal processing means in an orthogonal plane having the optical path as a rotation axis.   9. The method of adjusting an optical signal processing device according to claim 7, wherein the adjustment signal processing element elements are located at both ends of the plurality of signal processing element elements.   10. The method of adjusting an optical signal processing device according to claim 7, wherein a width of the adjustment signal processing element element in the intersecting direction is in a range of 0.5 Wx to 1.0 Wx.

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