JP4691665B2 - Dispersion compensator - Google Patents

Description

  The present invention relates to a dispersion compensator used in optical fiber communication or the like.

  High-capacity optical communication network systems that have shown rapid development in recent years are shifting from point-to-point systems, which have been the mainstream, to ring-mesh systems. This is because the ring-mesh type system can flexibly cope with changes in communication demand between nodes by using a transparent wavelength selective switch or the like that processes an optical signal in an optical state. Specifically, there is an advantage that the amount of on-site work accompanying the opening and closing of a new path can be greatly reduced by the dynamic switching of wavelength paths. However, in a ring-mesh network, the path length also changes as the wavelength path is switched, so the chromatic dispersion value of the path also changes dynamically.

  A conventional dispersion compensator is of a type in which a dispersion compensation fiber or a dispersion compensation amount is fixed, and is different for each WDM wavelength when the wavelength path distance is different in the network of the ring mesh type configuration as described above. The variance value could not be set. For this reason, adaptability is also required for dispersion compensation of wavelength paths in optical communications.

  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 an arrayed waveguide grating (hereinafter referred to as AWG) 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. 11 is a configuration diagram illustrating an example of a tunable dispersion compensator using a PLC. The input optical signal 100 to which dispersion compensation is applied is given a predetermined dispersion value by the variable dispersion compensator 200, and an output optical signal 106 is obtained. The input waveguide 101 to which the input optical signal 100 is input is first connected to the first AWG and the input optical signal is demultiplexed. The first AWG includes a first slab waveguide 102a, a first arrayed waveguide 103a, and a second slab waveguide 102b. The demultiplexed optical signal is input to the phase modulator 107. In the phase modulator 107, after a predetermined phase difference is given for each wavelength, it is input to the second AWG and multiplexed. The second AWG includes a third slab waveguide 102c, a second array waveguide 103b, and a fourth slab waveguide 102d. The fourth slab waveguide 102 d is connected to the output waveguide 104.

  In the waveguide type phase modulator 107, a phase difference φ expressed by a quadratic function with respect to the wavelength is given to the optical signal. That is, a dispersion compensation value corresponding to the coefficient of the quadratic function is given to the optical signal. Although the phase modulator 107 is not shown in FIG. 11, the waveguide refractive index in the phase modulator 107 can be changed by, for example, including a temperature variable heater and performing temperature control. By this temperature control, the variable dispersion compensation can be realized by changing the phase difference to be applied according to the wavelength path.

Japanese Patent Laid-Open No. 2002-250828 (pages 16, 19, 20, 20, 27, 29D, etc.) US Pat. No. 7,203,400 Specification US Pat. No. 7,106,923 Specification C. R. Doerr, et al. “Four-Stage Mach-Zehnder-Type Tunable Optical Dispersion Compensator With Single-Knob Control,” IEEE Photonics Technol. Lett., Vol. 17, No. 12, 2005, pp. 2637-2639

However, the tunable dispersion compensator using the PLC shown in FIG. 11 has a problem in that the transmission bandwidth is limited, which limits the optical signal processing in a wide band, and does not have sufficient performance. In FIG. 11, attention is focused on the optical path of the optical signal propagating through the tunable dispersion compensator 200. The optical signal having the center frequency λ ₀ in the target wavelength band is emitted from the first array waveguide 103a at the emission angle of approximately 0 ° in the first AWG as indicated by the optical path 50, and the phase modulator 107 A predetermined phase difference is given through the vicinity of the center. Thereafter, the second AWG also follows the same optical path as that of the first AWG, and enters the output waveguide 104 vertically at the end surface A of the fourth slab waveguide 102d.

However, an optical signal having a peripheral wavelength at the end of the band far from the center wavelength λ ₀ of the target wavelength band is incident on the output waveguide 104 obliquely as in the optical path 51 indicated by the broken line. In principle, optical coupling loss occurs. An optical signal having a peripheral wavelength is demultiplexed from the first arrayed waveguide 103a with a certain emission angle, passes through a position off the center of the phase modulator 107, and is given a predetermined phase difference. Thereafter, the optical signal incident on the second arrayed waveguide 103b is incident on the end surface A of the fourth slab waveguide 102d with a certain angle θ, not perpendicular to the output waveguide 104. Since this θ increases as the distance from the center wavelength λ ₀ increases, the optical coupling loss generated at the end face A also increases. Accordingly, focusing on the transmission characteristics of the tunable dispersion compensator, the light transmittance decreases as the distance from the center wavelength λ ₀ increases.

  FIG. 12 is a diagram for explaining band limitation of transmission characteristics due to optical coupling loss in the tunable dispersion compensator. Due to the optical coupling loss in the peripheral wavelength band described above, the transmittance of the tunable dispersion compensator decreases at both ends of the transmission band as shown by the solid line in FIG. In order to operate the tunable dispersion compensator with a constant performance, the operation range is limited to a wavelength range having a transmittance of a certain value or more. Therefore, the decrease in transmittance limits the usable bandwidth of the tunable dispersion compensator. In order to perform dispersion compensation for a broadband optical signal that requires high-speed optical signal processing, it is essential to increase the bandwidth of the dispersion compensator, and excess loss due to the optical coupling loss at the connection surface of the output waveguide described above. Need to be resolved. The optical coupling loss is described as a problem of the incident angle θ of the optical signal with respect to the output waveguide 104 for convenience of explanation. However, when the optical waveguide is traced from the exit waveguide 104 with the exit waveguide 104 side as a base point, the same problem occurs at the boundary surface between the entrance waveguide 101 and the first slab waveguide. As a method for solving the above-described problem of limiting the transmission band of the tunable dispersion compensator, a tunable dispersion compensator in which two PLC type tunable dispersion compensation circuits are arranged symmetrically in a point-symmetric manner has been proposed (Non-Patent Document). 2).

  FIG. 13 is a diagram showing a configuration of a PLC type tunable dispersion compensator having a point-symmetric structure in the prior art. The variable dispersion compensator 201 has a configuration in which two variable dispersion compensators having the configuration shown in FIG. That is, the first tunable dispersion compensator 111 a and the second tunable dispersion compensator 111 b are arranged so as to have a point-symmetric configuration as a whole with respect to the center point of the connection surface 112. The configuration of each tunable dispersion compensator is the same as that of the dispersion compensator described with reference to FIG. 11, and thus detailed description is omitted, but it should be noted that each tunable dispersion compensator has phase modulators 107a and 107b, respectively. I want. That is, in the tunable dispersion compensator 201, since the optical signal passes through the phase modulator twice, a dispersion compensation value that is twice that of the configuration shown in FIG. 11 is given.

In the configuration shown in FIG. 13, the optical signal always enters the output waveguide 104 perpendicularly at the end face A where the slab waveguide 102h of the second variable dispersion compensator 111b and the output waveguide 104 are connected. There was a feature. That is, regardless of whether or not the center wavelength λ ₀ is the target of the tunable dispersion compensator, as shown by the optical path 50, an optical signal of any wavelength enters the output waveguide 104 perpendicularly. Therefore, no optical axis shift occurs in the output waveguide 104. Therefore, no optical coupling loss occurs regardless of the wavelength. This is because the elements of the tunable dispersion compensator 201 are arranged symmetrically about the midpoint of the boundary line 112 between the slab waveguide 102d and the slab waveguide 102e. With this configuration, a decrease in the transmittance in the peripheral wavelength band indicated by the solid line in FIG. 12 is significantly suppressed, and the transmission band is flattened to realize a wider band.

  However, since the tunable dispersion compensator having the configuration shown in FIG. 13 is configured by cascading two tunable dispersion compensators, a total of four arrayed waveguides 103a to 103d and eight slab waveguides 102a to 102h are provided. Consists of a number of elements. Therefore, it is necessary to form a large-scale circuit on the substrate constituting the PLC. The chip area for configuring one dispersion compensator 201 is large, and the cost is high. In addition, the manufacturing yield may be reduced due to the complexity of the circuit configuration. In addition, the optical loss due to the size of the entire circuit increases. A tunable dispersion compensator having a line symmetric structure, which will be described below, can be used to solve the problems such as the size of the chip and the complexity of the circuit configuration.

  FIG. 14 is a block diagram showing a tunable dispersion compensator according to another prior art. This variable dispersion compensator has a configuration in which six slab waveguides 102 a to 102 f and three arrayed waveguides 103 a to 103 c are connected between an input waveguide 101 and an output waveguide 104. The arrayed waveguide 103b has a line-symmetric structure with the transverse line (X1-X2) including each waveguide midpoint as a symmetry axis, and two variable dispersion compensators 131a and 131b are formed across the symmetry axis. There is a feature. Also in this configuration, the optical signal propagates in one direction from the input waveguide 101 to the output waveguide 104 and has a so-called transmission type configuration. (See Patent Document 3 and Non-Patent Document 1)

  If the optical path through which the optical signal propagates is traced from the input waveguide 101 side and the configuration is described in detail, the input waveguide 101 is first connected to the first slab waveguide 102a. The optical signal is further demultiplexed by the first arrayed waveguide 103a and propagates through the second slab waveguide 102b and the third slab waveguide 102c. Between the second slab waveguide 102b and the third slab waveguide 102c, there is a waveguide-type first phase modulator 107a. The third slab waveguide 102c is further connected to the arrayed waveguide 103b. Here, each waveguide of the second arrayed waveguide 103b has a double optical path difference between adjacent waveguides as compared to the first arrayed waveguide 103a, and includes a line including the midpoint of each waveguide ( X1-X2) has a line-symmetric structure. Therefore, it should be noted that the second arrayed waveguide 103b has the same configuration as that obtained by connecting the two first arrayed waveguides 103a in a mirror-symmetric manner.

  As described above, the first variable dispersion compensator 131a is configured by the first portion from the first slab waveguide to the line symmetry axis (X1-X2) of the second slab waveguide. . Furthermore, the fourth slab waveguide 102d, the fifth slab waveguide 102e, the third array waveguide 103c, and the second array waveguide are separated from the second portion other than the symmetry axis (X1-X2) of the second slab waveguide. The second tunable dispersion compensator 131b is configured by up to six slab waveguides 102f. A waveguide-type second phase modulator 107b is provided between the fourth slab waveguide 102d and the fifth slab waveguide 102e.

  The first slab waveguide 102a and the sixth slab waveguide 102f, the second slab waveguide 102b and the fifth slab waveguide 102e, and the third slab waveguide 102c and the fourth slab waveguide 103d are respectively They have the same shape and are arranged symmetrically with respect to the (X1-X2) axis. Therefore, the variable dispersion compensator as a whole has a line-symmetric structure with respect to the symmetry axis (X1-X2).

Referring also to the configuration of the first prior art variable dispersion compensator shown in FIG. 13, it can be easily understood that the optical axis shift does not occur in the optical path of the optical signal even in the variable dispersion compensator shown in FIG. right. Here, for the sake of simplicity, attention is focused on the optical path in the line symmetry axis (X1-X2). An optical signal having the center wavelength λ ₀ of the wavelength band targeted by the tunable dispersion compensator passes through the center of each of the phase modulators 107 a and 107 b while following the optical path 50 and is given a predetermined phase difference. On the other hand, when an optical signal having a peripheral wavelength at the end of the band far from the center wavelength λ ₀ of the target wavelength band is observed, the optical path 51 indicated by the broken line is traced. The optical signal propagating in the optical path 51 is transmitted through a position off the center of the phase modulators 107a and 107b to give a predetermined phase difference, and propagates in the peripheral portion of the second arrayed waveguide 103b. Here, due to the symmetry of the structure of the second arrayed waveguide 103b and the symmetry of the overall configuration of the tunable dispersion compensator, the optical path 51 is on the symmetry axis regardless of whether the optical path 51 is tracked from either the input side or the output side. It will be understood that the optical axis shift is smooth and continuous with no optical axis misalignment.

  Compared with the configuration of the prior art shown in FIG. 13, the configuration of the tunable dispersion compensator of the prior art shown in FIG. 14 aligns the input and the output on the same side of the entire circuit, and the configuration shown in FIG. The entire structure is folded back. Therefore, the total length of the circuit is short, and the chip area can be reduced as compared with the configuration of FIG. In addition, since the number of circuit components is smaller, optical loss can be reduced.

  The arrangement of the components shown in FIG. 13 is essentially a point-symmetric configuration, and therefore cannot be applied to a reflective line-symmetric configuration using a mirror. This means that the configuration shown in FIG. 13 can be applied only to the transmission-type variable dispersion compensator, and is generally not applicable to the reflection-type variable dispersion compensator which is excellent in terms of downsizing and cost reduction. is doing. Further, the phase modulator in the configuration shown in FIG. 13 is limited to a transmission type and a waveguide type configuration. Therefore, a spatial phase modulation element using liquid crystal or the like as described in the background art cannot be used.

  The prior art variable dispersion compensator shown in FIG. 14 achieves circuit miniaturization with a line-symmetric configuration. However, as with the variable dispersion compensator shown in FIG. 13, for example, a high dispersion value can be given throughout the dispersion compensator and the flexibility of phase control is excellent, such as LCOS (Liquid crystal on silicon). It had the disadvantage that the spatial phase modulator could not be used. The phase difference of the waveguide type phase modulator is limited, and a large wavelength dispersion cannot be given to the dispersion compensator. For example, when a waveguide type phase modulator using an arrayed waveguide having an FSR of 100 GHz and a thermo-optic phase modulator is used, only a dispersion compensation value of about ± 100 ps / nm can be obtained.

  Further, in the conventional variable dispersion compensator, coupling loss occurs unless the center wavelengths of the two arrayed waveguides are exactly matched. In particular, when an arrayed waveguide with a small FSR is used to obtain a large chromatic dispersion, the required wavelength accuracy becomes very high. For example, in the case of a 100 GHz FSR, an accuracy of about 0.01 nm is required. This is an accuracy value smaller than a manufacturing error of a general array waveguide, and a special manufacturing process is required.

  The present invention has been made in view of such problems, and the object of the present invention is to provide a variable dispersion that has a wide band characteristic with a flat transmission band and can provide a high dispersion compensation value by a larger phase difference. It is to realize a compensator. A spatial phase modulator capable of flexible phase setting can be used to achieve more flexible variable dispersion compensation performance.

In order to achieve the above object, according to the present invention, a first spectroscopic unit that emits an input optical signal at an angle corresponding to a wavelength, and the first spectroscopic unit emits the optical signal. First condensing means for condensing the optical signal, a first spatial phase modulator for providing a predetermined phase amount to the optical signal collected by the first condensing means, and the first A second condensing unit that collimates the optical signal emitted from the spatial phase modulator, and is disposed opposite to the first spectroscopic unit around the position of the first spatial phase modulator, A second spectroscopic means for emitting the optical signal collimated by the second condensing means with an equiphase surface independent of the wavelength, and connected to the second spectroscopic means via the equiphase surface; a third spectral means for emitting at an angle corresponding optical signals having the equal phase plane on the wavelength, the third A third condensing unit for condensing the optical signal emitted from the optical unit; a second spatial phase modulator for providing a predetermined phase amount to the optical signal collected by the third condensing unit; A fourth condensing means for collimating an optical signal emitted from the second spatial phase modulator, and a third converging means centered on the position of the second spatial phase modulator. Light having each wavelength when the signal light is condensed on the first spatial phase modulator by the first spectroscopic means and the first condensing means. and the condensing position of the signal, the condensing position of the optical signal of each wavelength in the case where is focused on the first spatial phase modulator on by the signal light second spectroscopic unit and the second focusing means DOO equal, the second spatial phase variations by the signal light third spectroscopic means and said third focusing means A focusing position of the optical signal of each wavelength in the case that has focused on the vessel, condensing the signal light to the second spatial phase modulator on by the fourth spectroscopic unit and the fourth focusing means And the light collecting positions of the optical signals of the respective wavelengths are determined by the second light collecting means, the second light separating means, the third light separating means, and the third light collecting means. The sum of the linear dispersion value determined by the first spectroscopic means and the first light collecting means and the linear dispersion value determined by the fourth spectroscopic means and the fourth light collecting means. The dispersion compensator is characterized in that

The invention according to claim 2 is the dispersion compensator according to claim 1, wherein the first spectroscopic means and the fourth spectroscopic means are at least one input waveguide formed on a substrate; A slab waveguide connected to the input waveguide; and an arrayed waveguide composed of a plurality of waveguides connected to the slab waveguide and having adjacent optical path length differences. The waveguide light is configured to be coupled to the space from the end face of the substrate, and the second spectroscopic unit and the third spectroscopic unit are formed on the substrate and are connected to each other via the equiphase plane. The adjacent waveguides each have an arrayed waveguide composed of a plurality of waveguides having a constant optical path length difference, and the guided light of each arrayed waveguide is coupled to the space from each end surface opposite to the equiphase surface. Each of which is configured to .

According to a third aspect of the present invention, there is provided: a first spectroscopic unit that emits an input optical signal at an angle corresponding to a wavelength; a first condensing unit that condenses the optical signal emitted from the first spectroscopic unit; A spatial phase modulator that gives a predetermined phase amount to the optical signal collected by the first condensing means, and a second condensing means that collimates the optical signal emitted from the spatial phase modulator; The optical signal arranged opposite to the first spectroscopic means with the position of the spatial phase modulator as the center and parallelized by the second condensing means is emitted with an equiphase surface independent of wavelength. Each of the first spectral means and the first light collecting means formed on the spatial phase modulator. a focusing position of the optical signal wavelength, the second spectral means and said second current A dispersion compensator, characterized in that the focusing position of the optical signals of each wavelength are formed on the spatial phase modulator are equal by means.

According to a fourth aspect of the present invention, there is provided a first spectroscopic unit that emits an input optical signal at an angle corresponding to a wavelength, a first condensing unit that condenses the optical signal emitted from the first spectroscopic unit, A second condensing means for collimating the optical signal emitted from the first condensing means, and an optical signal emitted from the second condensing means is emitted with an equiphase surface independent of the wavelength; Second spectroscopic means and a mirror for turning back the optical path of the optical signal on the equiphase surface, and the first spectroscopic means and the second condensing means by the first spectroscopic means and the first condensing means . a focusing position of the optical signals of each wavelength are formed on the main optical axis perpendicular plane in the optical path midpoint between the spectroscopic means, the first by the second spectroscopic unit and the second focusing means Formed on the vertical plane of the main optical axis at the intermediate point of the optical path between the spectroscopic means and the second spectroscopic means. That of each wavelength optical distance between the focusing position of the optical signal and equal rather the first spectroscopic means and said first focusing means, and said second focusing means and the second The dispersion compensator further includes a moving mechanism that varies an optical distance between the spectroscopic means.

A fifth aspect of the present invention is the dispersion compensator according to the third aspect, wherein the spatial phase modulator is a reflection type, and the first condensing unit and the second condensing unit are combined into one concentrator. It also serves as a light means.

The invention of claim 6 is the dispersion compensator according to claim 4, further comprising an optical path conversion mirror at an intermediate point of the optical path between the first condensing unit and the second condensing unit, The first condensing unit and the second condensing unit are combined with one condensing unit.

The invention according to claim 7 is the dispersion compensator according to claim 5 or 6, wherein the first spectroscopic means and the second spectroscopic means are formed on the same substrate with a common spectral plane. It is a waveguide type spectroscopic means or an arrayed waveguide type spectroscopic means arranged in a stack in parallel with each spectral plane in the vertical direction.

The invention according to claim 8 is the dispersion compensator according to any one of claims 3 to 7, wherein the first spectroscopic means includes at least one input / output waveguide formed on a substrate, and the input / output waveguide. A slab waveguide connected to the waveguide, and an arrayed waveguide composed of a plurality of waveguides connected to the slab waveguide and having adjacent optical path length differences, and the guided light of the arrayed waveguide And the second spectroscopic means has an arrayed waveguide composed of a plurality of waveguides in which adjacent waveguides have a constant optical path length difference, and The guided light of the arrayed waveguide is configured to be coupled to a space from a substrate end surface opposite to the equiphase surface.

The invention of claim 9 is the dispersion compensator according to claim 8, further comprising a wavefront tilt element between the arrayed waveguide of the second spectroscopic means and the mirror, It is characterized in that it is optically coupled with two input / output waveguides at different junctions of the slab waveguide of the spectroscopic means.

A tenth aspect of the present invention is the dispersion compensator according to any one of the first to ninth aspects, wherein at least one of the first spectroscopic means and the second spectroscopic means outputs a condensing signal light. The light is emitted and includes a light collecting function of the at least one light collecting means.

  As described above, according to the present invention, a variable dispersion compensator having a wide-band transmittance characteristic with a flat transmission band and a higher dispersion compensation value can be realized by setting a large phase difference. it can. By making it possible to use a spatial phase modulator capable of flexible phase setting, highly flexible variable dispersion compensation performance can be realized, and the conditions of manufacturing errors of AWG can be relaxed.

  The tunable dispersion compensator of the present invention significantly reduces the optical coupling loss in the peripheral band of the operating band by combining the PLC and the spatial optical system and arranging the components in line symmetry. There is also a feature in a configuration in which a reflective spatial phase modulator can be used. Since a reflective spatial phase modulator such as LCOS can be used, a large dispersion compensation value can be set, and a more flexible dispersion compensation pattern can be realized.

  FIG. 1 is a configuration diagram illustrating a tunable dispersion compensator including a spatial optical system according to the first embodiment of the present invention. The variable dispersion compensator of the present invention has a configuration in which a spatial optical system including an arrayed waveguide circuit having a PLC configuration and a spatial phase modulator is combined. The two arrayed waveguide circuits are arranged to face each other through the spatial optical system, and the center wavelength optical axes can be easily matched.

  More specifically, the first AWG 10a includes an input waveguide 1, a slab waveguide 2, and an arrayed waveguide 3a as a waveguide type circuit based on PLC. A second AWG 10b facing the first AWG 10a is further arranged via a spatial optical system to be described later. The second AWG 10b has an arrayed waveguide 3b and a mirror 8. The mirror 8 is formed on an equiphase surface independent of the wavelength, which is formed by the spectral action of the arrayed waveguide 3b. The mirror 8 operates so as to constitute two variable dispersion compensators optically symmetrically arranged in the present variable dispersion compensator with the mirror forming surface as the axis of symmetry. That is, the first variable dispersion compensator configured by the forward optical path from the first AWG 10a to the mirror 8 and the second variable dispersion compensator configured by the return optical path from the mirror 8 to the first AWG 10b. Note that the above forms an optically symmetrically arranged system. Further, the optical path of the mirror 8 is not folded back, and the optical path of the axisymmetric return path is developed on the extension line, and the first dispersion compensator and the second dispersion compensator are separately prepared and connected. It is also clear that a variable dispersion compensator having a function equivalent to that of FIG. 1 can be configured.

  A spatial optical system is configured along the z-axis direction in which the optical signal propagates. That is, the optical signal emitted from the end face of the first AWG 10b is first collimated in the thickness direction of the AWG substrate by the cylindrical lens 11a. The optical signal that has passed through the cylindrical lens 11a is condensed by the first condenser lens 12a. The collected optical signal passes through the transmissive spatial phase modulator 17 and is given a predetermined phase difference. The optical signal given the phase difference is further incident on the second AWG 10b via the second condenser lens 12b and the cylindrical lens 11b.

  In order to obtain optical coupling between the AWG 10a and the AWG 10b, it is necessary to match the condensing positions of the optical signals of the respective wavelengths on the spatial phase modulator 17 by the left and right optical systems including the respective AWGs. That is, the value of the linear dispersion determined by the AWG 10a and the condensing lens 12a and the wavelength-dependent direction on the dispersion axis need to be equal to the value of the linear dispersion determined by the AWG 10b and the condensing lens 12b and the wavelength-dependent direction on the dispersion axis, respectively. is there.

  As described above, when the second variable dispersion compensator is formed on the extended line of the position of the mirror 8 without using the mirror 8, it is determined by the AWG and the condenser lens included in the second dispersion compensator. The two sets of linear dispersion values and directions must match. Here, it is not necessary that the linear dispersion values match between the first dispersion compensator and the second dispersion compensator. However, even in this case, the first dispersion compensator and the second dispersion compensator need to have the same linear dispersion direction because of the necessity of flattening the transmission band as described later. That is, the linear dispersion value when the spatial phase modulator of the first dispersion compensator is regarded as one spectroscope up to the spatial phase modulator of the second dispersion compensator is regarded as the first dispersion compensation. It is necessary to connect the two dispersion compensators on the above-described equiphase plane so that the sum of the linear dispersion value of the detector and the linear dispersion value of the second dispersion compensator is obtained. This condition can be satisfied if at least the first dispersion compensator and the second dispersion compensator are symmetrical with respect to the connected equiphase planes. However, if attention is paid to the direction of linear dispersion, the flatness of the transmission band can be satisfied even if the structure is not completely symmetric.

  The function as a tunable dispersion compensator is realized by giving a phase difference corresponding to the wavelength to the optical signal by the spatial phase modulator 17. Specifically, when the optical signal passes through the spatial phase modulator 17, a phase difference having a quadratic function profile with respect to the x-axis is given to the optical signal.

The optical signal having the center wavelength λ ₀ of the transmission band targeted by the tunable dispersion compensator is emitted vertically from the end face of the first AWG 10 a as shown by the solid line optical path 50, and the center of the spatial phase modulator 17. The phase difference is given through the part, and enters the second AWG 10b perpendicularly. On the other hand, when an optical signal having a peripheral wavelength at the end of the band far from the center wavelength λ ₀ of the target wavelength band is observed, the optical path 51 indicated by the broken line is traced.

  Generating a phase difference having a quadratic function profile means that the spatial phase modulator 17 acts as a lens. Therefore, an optical signal having a peripheral wavelength is bent like an optical path 51. The light is condensed again by the second condenser lens 12b, and the incident position on the second AWG 10b is slightly shifted from the optical path 50. However, since the incident angle is maintained, the forward optical path and the backward optical path coincide.

  In the second AWG 10b, the mirror 8 is formed on the equiphase surface of the arrayed waveguide 12b. In the mirror 8, the optical signal is reflected, propagates in the reverse direction of the z-axis using the same optical path 50 or optical path 51 as the above-described forward path, and returns to the first AWG 10a. In the entire tunable dispersion compensator, the phase difference is given twice by the spatial phase modulator 17 in the forward path and the return path across the mirror 8. The optical signal returns to the same position on the emission end face of the first AWG 10 a while maintaining the same emission angle, and the optical signal is input to and output from the input / output waveguide 1 vertically. Regardless of the wavelength of the optical signal, the optical axis shift does not occur in either the forward path or the return path. Similar to the prior art, the lowering of the transmittance in the peripheral wavelength band is greatly suppressed, and the transmission band is flattened to realize a wider band.

  According to this embodiment, it is possible to use a spatial phase modulator that can give a large phase difference and has excellent phase modulation characteristics, such as a liquid crystal, a nonlinear crystal, and a variable focus lens.

  In the variable dispersion compensator of this embodiment, even if there is an error in the center wavelength of the two array waveguides, the relative position of the two array waveguide chips or the distance between the condenser lens and the phase modulation element is finely adjusted. By doing so, the bond can be restored.

  In the present embodiment, the arrayed waveguide type spectroscopic means is used. However, the same effect as in the present embodiment can be obtained even if another angular dispersive element such as a bulk grating element is used as the spectroscopic means.

  Furthermore, in this embodiment, since the arrayed waveguide type spectroscopic means is used, an optical system for shaping the input light into an appropriate beam system, which is necessary when a bulk grating element is used, is not required, and the size and cost can be reduced. It becomes possible.

  In the tunable dispersion compensator of the present embodiment, the spatial phase modulator 17 is a transmission type that transmits an optical signal and imparts a phase difference. However, by using a reflection type that reflects an optical signal, the circuit configuration can be further increased. Can be simplified.

  FIG. 2 is a block diagram showing a tunable dispersion compensator including a spatial optical system according to the second embodiment of the present invention. In the present embodiment, the configuration shown in FIG. 1 is used in that the two arrayed waveguides 3a and 3b are formed on the same substrate of the AWG 10 by using the reflective spatial phase modulator 17. Is different. The following description will be made with attention paid to differences from the configuration shown in FIG.

  By using the reflective spatial phase modulator 17, the functions of the two condensing lenses 12a and 12b and the two cylindrical lenses 11a and 11b in FIG. 1 are changed to one condensing lens 12 and one cylindrical lens 11 respectively. Can also be used. The input / output waveguide 1, the slab waveguide 2, the first array waveguide 3 a, the second array waveguide 3 b, and the mirror 8 are integrally formed on one AWG substrate 10. Needless to say, the two arrayed waveguides 3a and 3b are formed on the same plane, but can be formed on different substrates.

The optical signal having the center wavelength λ ₀ of the transmission band targeted by the tunable dispersion compensator is emitted in the z-axis direction perpendicularly from the end face of the first arrayed waveguide 3a of the AWG 10, as indicated by the optical paths 50a and 50b. The light is reflected after being given a phase difference at the center of the spatial phase modulator 17. Here, in the forward path 50a traveling in the z-axis direction, the optical signal is transmitted through a portion off the center of the condenser lens 12 and is incident on the spatial phase modulator 17 with a slight inclination angle. After being reflected by the spatial phase modulator 17, in the forward path 50b traveling in the reverse direction of the z axis, the optical signal passes through different positions of the condenser lens 12 and propagates toward the arrayed waveguide 3b. The optical signal is reflected by the mirror 8 formed on the equiphase surface through the arrayed waveguide 3b, and then continues to the arrayed waveguide 3a in the opposite direction along the same optical path as the optical paths 50b and 50a described above as the return path. Propagate.

  An optical signal having a peripheral wavelength is given a phase difference having a quadratic function profile at different positions of the spatial phase modulator 17, and the spatial phase modulator 17 acts as a lens as in the third embodiment. Means. An optical signal having a peripheral wavelength follows the optical paths 51a and 51b, and enters the second AWG 10b at a position slightly shifted from the optical path 50b. However, since the incident angle is maintained, the forward optical path 51b coincides with the return optical path 51b.

  Reflective spatial phase modulators such as LCOS and optical addressing type liquid crystal cells have a feature that the number of pixels is large and phase setting is possible with high spatial resolution. In this embodiment, since the spatial phase modulator 17 is a reflection type, the phase can be set with high wavelength resolution. Since one wavelength channel is controlled by a large number of pixels, a large dispersion can be given without restriction by giving a Fresnel lens-like phase difference pattern. Further, not only the phase of the quadratic function shape but also a higher order phase shape can be generated to perform higher order dispersion compensation.

  Further, the spatial optical system can be configured with a half optical path length of the first embodiment. Furthermore, the slab waveguide 2, the arrayed waveguides 3a and 3b, and the mirror 8 can be formed on the same substrate and configured by a single PLC. Compared with the first embodiment that requires two separate PLCs, the overall circuit configuration can be further simplified and the cost can be reduced.

  FIG. 3 is a block diagram showing another variable dispersion compensator including a spatial optical system according to the third embodiment of the present invention. This is a modification of the second embodiment shown in FIG. In the second embodiment, the two arrayed waveguides 3a and 3b are configured on the same plane. However, in the present embodiment, the stacks are formed on different AWG substrates, and the two substrates are stacked. It is different in that it is an arrangement configuration. In FIG. 3, two upper plan views (a) and (b) each including two AWGs 10a and 10b as viewed from the xz plane, and a side view (c) as viewed from the yz plane. Is shown. An input / output waveguide 1, a slab waveguide 2a, and an arrayed waveguide 3a are formed in the first AWG 10a on the upper stage of the stack. An arrayed waveguide 3b and a mirror 8 are formed in the second AWG 10b at the lower stage of the stack. The optical system is separated in the y-axis direction by the cylindrical lens 11a disposed near the exit end face of the first AWG 10a, the cylindrical lens 11b disposed near the exit end face of the second AWG 10b, and the condenser lens 12. . Therefore, the optical path is separated into the optical paths 50a and 51a and the optical paths 50b and 51b in the y-axis direction before and after the spatial phase modulator 17.

The optical paths 50a and 50b of the optical signal having the center wavelength λ ₀ of the transmission band targeted by the tunable dispersion compensator and the optical paths 51a and 51b of the optical signal having the peripheral wavelength are separated in the y-axis direction. Except for this, the operation is the same as in the second embodiment. As in the second embodiment, the overall length of the tunable dispersion compensator can be reduced by shortening the length of the spatial optical system. In both the second and third embodiments, an LCOS spatial phase modulator and a MEMS type phase modulator excellent in phase resolution can be used as the spatial phase modulator. By using a phase modulator with a large number of pixels and high resolution, such as LCOS, not only setting chromatic dispersion by repeating single-channel chromatic dispersion compensation operation for each FSR, but also independently for multiple channels. Dispersion can be set. Thus, the ability to set the dispersion compensation characteristics in a variety of ways is an excellent feature that cannot be obtained with a conventional variable dispersion compensator that can only use a waveguide type phase modulator.

  In the variable dispersion compensators of the second and third embodiments, even if there is an error in the center wavelengths of the two arrayed waveguides, by finely adjusting the distance between the condenser lens and the spatial phase modulator, The bond can be restored.

  As described in the first embodiment, the configuration of each of the embodiments described above can be set to the operating wavelength by arranging the components so as to effectively form two variable dispersion compensators in line symmetry. Regardless of the fact that an optical path that does not cause an optical axis misalignment is formed. In any of the embodiments, a mirror is arranged on the symmetry axis at the midpoint of all the optical paths so as to form a line-symmetric configuration, thereby realizing a reduction in size and simplification of the circuit. In the above-described embodiment, a highly functional spatial phase modulator is used, but a tunable dispersion compensator can be realized with a simpler configuration.

  FIG. 4 is a block diagram showing a tunable dispersion compensator including a spatial optical system according to the fourth embodiment of the present invention. This embodiment is different in that the distance between the AWG 10 and the condenser lens 12 is changed by replacing the spatial phase modulator in the second embodiment with a mirror 8a and further translating the AWG 10 on the z-axis. .

  It is known that when the distance from the exit end face of the AWG 10 to the condenser lens 12 is different from the focal length of the condenser lens 12, a secondary phase difference can be imparted to the x-axis in the wavelength axis direction at the position of the mirror 8a. Therefore, by moving the AWG 10 and the cylindrical lens 11 together and moving on the z-axis, it is possible to give a secondary phase difference on the mirror 8a surface without using a spatial phase modulator.

  Also in the tunable dispersion compensator having the above-mentioned translation mechanism, two mirrors 8b formed on the equiphase surface of the second arrayed waveguide 3b formed on the AWG 10 are equivalently arranged in line symmetry. A variable dispersion compensator can be configured. Compared to the second embodiment, the configuration is such that the spatial phase modulator is replaced with a mirror 8a, and a decrease in the transmittance in the peripheral wavelength band is greatly suppressed, and the transmission band is flattened to realize a wider band. Is the same as in the other embodiments.

  FIG. 5 is a block diagram showing a tunable dispersion compensator including a spatial optical system according to the fifth embodiment of the present invention. In the present embodiment, the spatial phase modulator in the fifth embodiment is replaced with a mirror 8a, and the AWGs 10a and 10b are translated on the z-axis to change the distance between the AWGs 10a and 10b and the condenser lens 12. It is different in point.

  Similar to the fourth embodiment, the AWGs 10a and 10b and the cylindrical lenses 11a and 11b are integrated and moved on the z-axis, so that a second-order phase difference is obtained on the mirror 8a without using a spatial phase modulator. Can be granted. As in the fourth embodiment, it is possible to significantly reduce the transmittance decrease in the peripheral wavelength band and flatten the transmission band to realize a wider band.

  Both the fourth embodiment and the fifth embodiment can avoid the problem of deterioration of characteristics due to the pixel gap associated with the phase modulator having pixels. For example, there is a merit in that a ripple problem occurring in the transmittance characteristic and the group delay characteristic does not occur. Although it has a high phase setting capability, it requires a complicated driving circuit and is characterized in that a relatively expensive spatial phase modulator is not used.

  Each of the embodiments described so far has a configuration in which both an input waveguide and an output waveguide are used as a single waveguide. Therefore, an external circulator is required to input and output an optical signal to the variable dispersion compensator. And Therefore, the input position and the output position of the optical signal at the boundary surface of the slab waveguide are separated by separating the condensing points by making the optical path length difference ΔL of the two opposing array waveguides slightly different. be able to.

FIG. 6 is a block diagram showing a tunable dispersion compensator including a spatial optical system according to the sixth embodiment of the present invention. In the present embodiment, the configuration of one arrayed waveguide 3a and the configuration of the other arrayed waveguide 3b in the second embodiment shown in FIG. 2 are different, and the input waveguide 1 and the output waveguide 4 are The difference is that they are provided separately. The first arrayed waveguide 3a has an optical path length difference ΔL = A between adjacent waveguides. On the other hand, the second arrayed waveguide 3b has an optical path length difference ΔL = A + α. The second arrayed waveguide 3b is a combination of ΔL = A having the same angular dispersion as the first arrayed waveguide 3a and ΔL = α for tilting the wavefront when the optical path is folded back at the mirror 8. Can be considered. By reciprocating the wavefront tilting element, the wavefront tilts by 2α / (array waveguide pitch). Corresponding to the inclination of the wavefront, the optical signal returning from the second array waveguide 3b to the first array waveguide 3a is condensed at a position different from the input waveguide 1 at the boundary of the slab waveguide 2. That is, when considering an optical signal having a center wavelength λ ₀ , an optical signal reaching the mirror 8 from the input waveguide 1 via the optical path 50 is output from the output waveguide 4 via the optical path 52 indicated by a broken line.

  Here, in the forward optical path 50 and the return optical path 52, a phase difference is given at different positions of the spatial phase modulator 7. However, since the second-order coefficient of the phase profile given by the spatial phase modulator acts as the chromatic dispersion value, the difference in position hardly affects. With the configuration of the present embodiment described above, input and output optical signals can be input and output from different waveguides of the AWG 10. Further, when the phase modulator 7 has a pixel structure, the condensing position on the forward path and the condensing position on the return path are shifted by a distance of (N + 0.5) times (N is an integer including 0) the pixel repetition period. Accordingly, it is possible to prevent an error in the phase addition amount caused by the gap between pixels from being added in the forward path and the backward path. No circulator or the like is required outside the tunable dispersion compensator. This embodiment can be applied to all other embodiments described so far that serve both as an input waveguide and an output waveguide.

  All of the above-described embodiments operate to focus on the spatial phase modulator using a bulk condenser lens, but omit the condenser lens by controlling the wavefront of the emitted light from the AWG. You can also

  FIG. 7A is a configuration diagram showing a tunable dispersion compensator including a spatial optical system according to the seventh embodiment of the present invention. This embodiment is different from the first embodiment in that the two condensing lenses 12a and 12b do not exist in the configuration shown in FIG. 1 and the configurations of the arrayed waveguides 3a and 3b are different. In the first embodiment, the waveguide lengths of the arrayed waveguides 3a and 3b are designed so that plane waves are emitted from the emission end faces of the AWGs 10a and 10b. On the other hand, the arrayed waveguides 33a and 33b in the present embodiment are designed such that the lengths of the respective waveguides are emitted so as to emit arc wavefronts from the emission ends of the AWGs 10a and 10b so as to be focused at the position of the spatial phase modulator 7. ing.

As shown in the optical path 50 of the optical signal having the center wavelength λ ₀ and the optical path 51 of the optical signal having the peripheral wavelength indicated by the broken line, the optical signal travels straight to the second AWG 10b with an arc wavefront. Incident. The arrayed waveguide 33b is designed to generate an arc wavefront, and reflects an optical signal while maintaining an effective line symmetry on the reflecting surface of the mirror 8.

  By applying this embodiment, the condensing lens can be omitted. By providing a condensing function by AWG, an optical system with less aberration and low loss can be formed. This embodiment can be applied to all configurations including the above-described arrayed-waveguide-type component and a spatial optical system.

  In each of the above-described embodiments, the mirror 8 formed on the equiphase surface of the second arrayed waveguide can be formed in the plane of the AWG substrate, but as shown in FIG. It can also be formed using the end face of the AWG substrate. That is, the mirror 18 can be more easily formed by forming a polishing surface on the side surface of the chip different from the light signal output end surface of the AWG 10 from the spatial optical system and coating the metal film. Since the arrayed waveguide 3 only needs to maintain a predetermined optical path length difference ΔL between the waveguides, the optical signal can be easily terminated perpendicularly to the chip end face by adjusting the arrangement of the arrayed waveguides. It is. A more specific embodiment of the variable dispersion compensator will be shown below.

  FIG. 8 is a block diagram showing a tunable dispersion compensator including a spatial optical system according to the eighth embodiment of the present invention. This embodiment is based on the configuration of the third embodiment of the stack arrangement and further adds a polarization diversity configuration in order to eliminate the polarization dependency. A comparison result of compensation characteristics between the present embodiment and a variable dispersion requirement device according to the prior art will also be described.

  FIG. 8 shows two upper top views (a) and (b) each including two AWGs 10a and 10b as viewed from the xz plane, and a side view (c) as viewed from the yz plane. Is shown. As shown in (a), the input and output of the first AWG 10a are connected to the optical network analyzer 35 via the circulator 38, and the transmission characteristics and the like of the variable dispersion compensator are measured.

  Only differences from the third embodiment will be described directly. Near the exit end face of the two AWGs 10a and 10b, a polarization separation crystal 36 is disposed to separate or combine the optical signal into a TE mode component and a TM mode component. Of the separated optical signals, the TE mode component optical signals traveling along the optical paths 61a and 61b are converted in polarization mode by polarization rotation elements 37a and 37b such as λ / 2 plates. In the optical path from the upper polarization rotator 37a to the lower polarization rotator 37b, the separated TE mode optical signal traveling through the optical paths 60a and 60b and the TM mode traveling through the optical paths 61a and 61b are converted to the TE mode. Since there is only an optical signal, only the TE mode exists. After the two polarization components are combined by the polarization separation crystal 36, the optical signal passes through the λ / 4 plate 38 and is reflected by the mirror 8 in the lower AWG 10b. Since it passes through the λ / 4 plate 38 twice, it undergoes polarization rotation. Therefore, polarization diversity is realized by TE-TM conversion even at an intermediate point of the entire optical path of the tunable dispersion compensator.

  For comparison, a variable dispersion compensator according to the configuration of the prior art is realized by a configuration in which reflected light from the spatial phase modulator 7 is folded back to the upper AWG 10a using only the upper AWG system in FIG. That is, the optical axis was adjusted with respect to the y-axis direction so that the optical signal returned directly from the spatial phase modulator 7 to the AWG 10a. The above-described configuration of the prior art is realized by implementing the waveguide configuration shown in FIG. 11 with a reflective configuration including a spatial optical system. Since it is configured to transmit through the spatial phase modulator 7 only once in the entire optical path, an optical axis shift similar to that described in the prior art occurs in the optical path for an optical signal having a peripheral wavelength in the transmission band. .

FIG. 9 is a diagram illustrating specific configuration parameters of each element of the tunable dispersion compensator according to the eighth embodiment. LCOS was used as the spatial phase modulator 7, and a phase difference having a profile corresponding to a quadratic function was given to the x-axis direction of the spectral axis. A pixel near the both end positions of the LCOS was given a phase difference equivalent to about 6λ ₀ with the center wavelength being λ ₀ .

  FIG. 10 is a graph showing the transmittance spectrum and group delay characteristics of the tunable dispersion compensator of the eighth embodiment in comparison with the prior art. If attention is paid to the transmittance spectrum shown in (a), it can be understood that the bandwidth characteristics of the transmittance according to the configuration of the present invention are remarkably flattened as compared with the prior art. A 1 dB bandwidth indicating a bandwidth in which the transmittance is reduced by 1 dB from the center wavelength is 90 GHz in the present invention, whereas the conventional type is 18 GHz. When the chromatic dispersion value is obtained based on the corresponding group delay characteristic shown in (b), it is -630 ps / nm according to the prior art and -1260 ps / nm according to the present invention.

In the configuration of the present invention, further by driving to provide the phase difference of the maximum 15Ramuda ₀ corresponds to LCOS, and can be set to any wavelength dispersion value of ± 3000 ps / nm. When a waveguide phase modulator using an arrayed waveguide with an FSR of 100 GHz and a thermo-optic phase modulator is used as in the prior art, only a dispersion compensation value of about ± 100 ps / nm can be obtained at most. In comparison, a large dispersion compensation value can be set.

  As described above in detail, according to the variable dispersion compensator of the present invention, it has a wide-band transmittance characteristic in which the transmission band is flattened, and a higher dispersion compensation value by setting a large phase difference. Can be realized. By making it possible to use a spatial phase modulator capable of flexible phase setting, highly flexible variable dispersion compensation performance can be realized, and the conditions of manufacturing errors of AWG can be relaxed.

  The present invention can be applied to optical communication. In particular, it is suitable for use in a network of a ring mesh type configuration using a wavelength selective switch.

It is a block diagram which shows the variable dispersion compensator which concerns on the 1st Embodiment of this invention. It is a block diagram which shows the variable dispersion compensator which concerns on the 2nd Embodiment of this invention. It is a block diagram which shows the variable dispersion compensator which concerns on the 3rd Embodiment of this invention. It is a block diagram which shows the variable dispersion compensator which concerns on the 4th Embodiment of this invention. It is a block diagram which shows the variable dispersion compensator which concerns on the 5th Embodiment of this invention. It is a block diagram which shows the variable dispersion compensator which concerns on the 6th Embodiment of this invention. It is a block diagram which shows the variable dispersion compensator which concerns on the 7th Embodiment of this invention. It is a block diagram of the variable dispersion compensator using the spatial phase modulator of the 8th Embodiment of this invention. It is a figure which shows the structural parameter of the variable dispersion compensator of 8th Embodiment. It is a figure which shows the graph of the dispersion compensation characteristic of the variable dispersion compensator of 8th Embodiment. It is a block diagram which shows an example of the variable dispersion compensator using PLC. It is a figure explaining the restriction | limiting of the transmission characteristic in a tunable dispersion compensator. It is a figure which shows the structure of the PLC type dispersion compensator with a point object structure. It is a figure which shows the structure of the PLC type dispersion compensator which has a line symmetrical structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,101 Input waveguide 2, 2a, 2b, 102a-102f Slab waveguide 3, 3a, 3b, 33a, 33b, 103a, 103b, 103c Array waveguide 4, 104 Output waveguide 7, 17 Spatial phase modulator 8 , 8a, 8b, 18 Mirror 10, 10a, 10b AWG
11a, 11b Cylindrical lenses 12, 12a, 12b Condensing lenses 36 Polarization separation crystals 37a, 37b λ / 2 plates 38 λ / 4 plates 39 Circulators 50, 50a, 50b, 52 Optical signal optical paths 51, 51a having central wavelengths 51b Optical paths of optical signals having peripheral wavelengths 111a, 111b, 131a, 131b Variable dispersion compensators 107, 107a, 107b Waveguide type phase modulators

Claims (10)

A first spectroscopic means for emitting an input optical signal at an angle corresponding to the wavelength;
First condensing means for condensing the optical signal emitted from the first spectroscopic means;
A first spatial phase modulator that gives a predetermined phase amount to the optical signal collected by the first light collecting means;
Second condensing means for collimating the optical signal emitted from the first spatial phase modulator;
The optical signal collimated by the second light converging means is disposed opposite to the first spectroscopic means with the position of the first spatial phase modulator as a center, and has an equiphase surface independent of wavelength. A second spectroscopic means for emitting
Is connected to the second spectroscopic unit through the equal phase plane, and a third spectral means for emitting at an angle corresponding optical signal to a wavelength having the equal phase surface,
Third condensing means for condensing the optical signal emitted from the third spectroscopic means;
A second spatial phase modulator that gives a predetermined phase amount to the optical signal collected by the third light collecting means;
Fourth condensing means for collimating the optical signal emitted from the second spatial phase modulator;
A fourth spectroscopic unit disposed opposite to the third spectroscopic unit with the position of the second spatial phase modulator as a center,
The condensing position of the optical signal of each wavelength when the signal light is condensed on the first spatial phase modulator by the first spectroscopic means and the first condensing means, and the signal light The condensing position of the optical signal of each wavelength when the light is condensed on the first spatial phase modulator by the two spectroscopic means and the second condensing means,
When the signal light is condensed on the second spatial phase modulator by the third spectroscopic unit and the third condensing unit, the condensing position of the optical signal of each wavelength, and the signal light The light collecting positions of the optical signals of the respective wavelengths when the light is condensed on the second spatial phase modulator by the four spectroscopic means and the fourth light collecting means,
The linear dispersion values determined by the second condensing means, the second spectroscopic means, the third spectroscopic means, and the third condensing means are the first spectroscopic means and the first collective means. dispersion compensator, characterized by the sum of linear dispersion value determined by linear dispersion value and the fourth spectroscopic unit and the fourth focusing means determined by light means. The first spectroscopic means and the fourth spectroscopic means are at least one input waveguide formed on a substrate, a slab waveguide connected to the input waveguide, and adjacent to the slab waveguide. And an arrayed waveguide composed of a plurality of waveguides having a certain optical path length difference, and configured to couple the guided light of the arrayed waveguide to the space from the end face of the substrate;
The second spectroscopic unit and the third spectroscopic unit are formed on a substrate, connected to each other via the equiphase surface, and adjacent waveguides from a plurality of waveguides having a constant optical path length difference. The dispersion according to claim 1, wherein each of the arrayed waveguides is configured to be coupled to a space from each end surface opposite to the equiphase surface. Compensator. A first spectroscopic means for emitting an input optical signal at an angle corresponding to the wavelength;
First condensing means for condensing an optical signal emitted from the first spectroscopic means;
A spatial phase modulator that gives a predetermined phase amount to the optical signal collected by the first light collecting means;
Second condensing means for collimating the optical signal emitted from the spatial phase modulator;
The optical signal arranged opposite to the first spectroscopic unit with the position of the spatial phase modulator as the center and parallelized by the second condensing unit is emitted with an equal phase plane independent of the wavelength. A second spectroscopic means;
A mirror that folds the optical path of the optical signal on the equiphase plane,
The condensing position of the optical signal of each wavelength formed on the spatial phase modulator by the first spectroscopic unit and the first condensing unit, the second spectroscopic unit and the second condensing unit The dispersion compensator is characterized in that the condensing position of the optical signal of each wavelength formed on the spatial phase modulator is the same. A first spectroscopic means for emitting an input optical signal at an angle corresponding to the wavelength;
First condensing means for condensing the optical signal emitted from the first spectroscopic means;
Second condensing means for collimating the optical signal emitted from the first condensing means;
A second spectroscopic means for emitting an optical signal emitted from the second light collecting means with an equiphase surface independent of wavelength;
A mirror that folds the optical path of the optical signal on the equiphase plane,
Light of each wavelength formed on the main optical axis vertical plane at the intermediate point of the optical path between the first spectroscopic unit and the second spectroscopic unit by the first spectroscopic unit and the first condensing unit The signal condensing position and the main optical axis vertical plane at the intermediate point of the optical path between the first spectroscopic unit and the second spectroscopic unit by the second spectroscopic unit and the second condensing unit optical distance between said first focusing means focusing position and is equal rather the first spectroscopic unit of the optical signals of each wavelength are formed, and the said second focusing means the A dispersion compensator further comprising a moving mechanism for changing an optical distance between the two spectroscopic means. 4. The dispersion compensator according to claim 3, wherein the spatial phase modulator is a reflection type, and the first condensing unit and the second condensing unit are combined with one condensing unit. . An optical path conversion mirror is further provided at an intermediate point of the optical path between the first light collecting means and the second light collecting means, and the first light collecting means and the second light collecting means are provided as one light collecting light. The dispersion compensator according to claim 4, wherein the dispersion compensator is also used.   The first spectroscopic unit and the second spectroscopic unit are arrayed waveguide type spectroscopic units formed on the same substrate with a common spectral plane, or stacked in parallel in the vertical direction on each spectral plane. 7. The dispersion compensator according to claim 5, wherein the dispersion compensator is an arrayed waveguide type spectroscopic unit. The first spectroscopic means includes at least one input / output waveguide formed on a substrate, a slab waveguide connected to the input / output waveguide, and a waveguide connected to the slab waveguide and adjacent to the slab waveguide. An arrayed waveguide composed of a plurality of waveguides having optical path length differences, and configured to couple the guided light of the arrayed waveguide from the end face of the substrate to space.
The second spectroscopic means has an arrayed waveguide composed of a plurality of waveguides in which adjacent waveguides have a constant optical path length difference, and the guided light of the arrayed waveguide is opposite to the equiphase surface. The dispersion compensator according to claim 3, wherein the dispersion compensator is configured to be coupled to a space from an end face of the substrate.   A wavefront tilt element between the arrayed waveguide of the second spectroscopic means and the mirror; and two input / output waveguides at different junctions of the slab waveguide of the first spectroscopic means; 9. The dispersion compensator according to claim 8, wherein the dispersion compensator is optically coupled.   2. The at least one of the first spectroscopic unit and the second spectroscopic unit emits condensing signal light and includes a condensing function of the at least one condensing unit. The dispersion compensator according to any one of 9 to 9.

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