JP6434879B2 - Optical signal monitoring device - Google Patents

Description

  The present invention relates to an optical signal monitoring device.

  With the increase in Internet traffic, the need for an increase in communication capacity in optical fiber communication is increasing. In order to meet this demand, the trend of increasing the speed and multi-level of modulated light passing through the fiber, and multiplexing in the wavelength direction, polarization direction, and spatial direction is becoming more and more advanced. In order to maintain the quality of the optical signal modulated in this way for a long period of time, an optical signal monitoring technique is important. For monitoring the optical signal, for example, an optical channel monitor (OCM) that measures the light intensity for each wavelength channel, an OSNR monitor that measures the S / N ratio of the optical signal, and a CD monitor that measures the chromatic dispersion (CD) of the optical signal. And a PMD monitor for measuring polarization mode dispersion (PMD). As a method for monitoring these, for example, the method of Patent Document 1 is used for OCM, the methods of Non-Patent Documents 1 and 2 are used for OSNR, and the method of Non-Patent Document 3 is used for PMD or CD. . In addition to the methods listed here, various monitoring methods have been proposed and each has its own characteristics.

JP 2003-204302 A International Publication No. WO2014 / 087673 Pamphlet

JHLee et al., “A Review of the Polarization-Nulling Technique for Monitoring Optical-Signal-to-Noise Ratio in Dynamic WDM Networks”, Journal of Lightwave Technology, Vol.24, No.11, pp.4162-4171, 2006 X. Liu et al., “OSNR Monitoring Method for OOK and DPSK Based on Optical Delay Interferometer”, IEEE Photonics Technology Letters, Vol. 19, No. 15, pp. 1172-1174, 2007 Y. K. Lize et al., “Independent and Simultaneous Monitoring of Chromatic and Polarization-Mode Dispersion in OOK and DPSK Transmission”, IEEE Photonics Technology Letters, Vol. 19, No. 1, JANUARY 1, 2007

  On the other hand, monitoring of optical signal quality requires different monitoring functions at the time of design / opening / operation / failure. For example, during operation, an optical channel monitor that can immediately detect disconnection of an optical signal is useful. However, monitoring of characteristics such as OSNR and the like that are directly connected to the BER is important at the time of circuit design and failure analysis. However, since these measuring apparatuses generally have different optical configurations, disposing all the monitoring functions in each optical node has a high barrier in terms of cost and size.

  In addition, in the conventional OSNR measurement, an ASE complement method is generally used in which the OSNR is monitored by linearly complementing the spontaneous emission (ASE) level outside the signal band and estimating the ASE-induced noise power ratio with respect to the optical signal power. Has been used. However, it is difficult to estimate the ASE level by the conventionally used ASE interpolation method due to the broadening of the optical signal bandwidth accompanying the increase in the symbol rate and the non-uniform spectral characteristics of the ASE light passing through the multistage optical filters. Therefore, there is a need for an in-band OSNR monitoring method that can directly estimate the noise power in the signal band. Furthermore, in the process of propagation of optical signals, it is generally known that PMD changes with time due to shaking of an aerial optical cable, contact of the maintenance operator with the optical cable, temperature change of the optical cable, etc. If the influence on the optical signal can be constantly monitored, it is expected that a more reliable optical communication system can be operated. Further, it is necessary to perform protection switching from the working path when the link is broken, and CD monitoring is required.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide an optical monitoring device capable of changing the optical monitoring function in a programmable manner according to the occasion.

  In order to solve the above problems, an invention described in an embodiment includes an input port for inputting an optical signal to be monitored, a plurality of pixels arranged in a matrix in a plane, and a drive for driving the pixels. A spatial light modulation element that emits light by changing the optical phase of the signal light input to each pixel by controlling the phase pattern of the plurality of pixels by the drive unit, and the light is emitted from the input port to the space An optical element that converts the angle and position of the emitted light of the signal light so that the signal light that has been emitted is irradiated onto the spatial light modulation element, and a light receiving port to which the light emitted from the spatial light modulation element is coupled, A light receiving element that measures the intensity of light coupled to the light receiving port, and a calculation unit that calculates a measurement value according to the monitor content of the optical signal based on the intensity of the light measured by the light receiving element, Sky The light modulation element controls the phase pattern of the plurality of pixels so that the signal light is output to a predetermined path with a predetermined intensity / phase and delay time according to the monitoring content of the optical signal. This is an optical signal monitoring device.

It is a figure which shows the structural example of the optical signal monitor apparatus using reflection type SLM. It is a figure which shows the other example of a structure of the optical signal monitor apparatus using reflection type SLM. It is a figure which shows the other example of a structure of the optical signal monitor apparatus using reflection type SLM. It is a figure which shows the other example of a structure of the optical signal monitor apparatus using reflection type SLM. It is a figure which shows the other example of a structure of the optical signal monitor apparatus using reflection type SLM. It is a figure which shows the other example of a structure of the optical signal monitor apparatus using reflection type SLM. It is an example which shows a light irradiation area | region in the structure of reflection type SLM seen from the z-axis direction. It is an example which shows the light irradiation area | region decomposed | disassembled into the wavelength channel in the structure of reflective SLM seen from the z-axis direction. Indicates. It is a figure which shows a blazed phase pattern. It is a figure shown about the example of a coupling | bonding of the light in a delay interferometer. It is a figure which shows the phase pattern which superimposed the sin wave of a different frequency on the sawtooth wave. It is a figure which shows the structure which divides area | region in the structure of reflection type SLM seen from the z-axis direction, and applies a different phase pattern to each. It is a figure explaining the structural example of a delay interferometer. It is a figure which shows the example which controlled the phase modulation element SLM so that 90 degree hybrid might be implement | achieved. It is a figure which shows the intensity | strength of the signal light couple | bonded with the light reception ports A and B in a 90 degree hybrid structure. It is a figure which shows the structural example of the optical switch integrated type optical signal monitoring apparatus using reflection type SLM. It is a figure which shows the other example of a structure of the optical switch integrated type optical signal monitoring apparatus using reflection type SLM.

Hereinafter, embodiments of the present invention will be described in detail.
[First Embodiment]
(Basic configuration of optical system)
FIG. 1 shows a configuration example of an optical signal monitoring apparatus using a reflection type SLM (Spatial Light Modulator) phase modulation element. In FIG. 1, the direction in which the input port and the light receiving port are arranged is shown as the y axis, and the direction in which the optical signal propagates is shown as the z axis. The optical signal monitoring device includes a plurality of optical fibers 11-i that are input ports, a plurality of collimating lenses 12-i provided corresponding to the optical fibers 11-i, an optical element 13, an SLM 14, and a collimating lens. The array 15-1 to 15-m, a plurality of optical fibers 16-1 to 16-m as light receiving ports, and optical power monitors 17-1 to 17-m are configured.

  The optical element 13 emits the light input from the optical fiber 11-i via the collimator lens 12-i toward the phase modulation element 14, and also reflects the light reflected from the phase modulation element 14 to the collimator lens array. It couple | bonds with the optical fibers 16-1 to 16-m through 15-1 to 15-m. As the optical element 13, means for changing the emission direction of the signal light so that the input light is emitted toward the phase modulation element 14 can be used. For example, a lens, a prism, a diffraction grating, or the like is used. Can do.

  The SLM 14 controls the phase pattern of the matrix pixels, and controls and outputs the light intensity, light phase, and delay time of the input light.

  In the optical signal monitoring apparatus shown in FIG. 1, the input m optical signals are emitted to the space via the optical fiber 11-i and given to the optical element 13 via the collimator lens 12-i. Here, i is a value corresponding to each input port number. The outgoing light from the optical element 13 is reflected by the SLM 14 and is again passed through the optical element 13 through the collimating lens arrays 15-1 to 15-m and applied to the optical fibers 16-1 to 16-m which are light receiving ports. Optical power monitors 17-1 to 17-m are connected to the subsequent stage of the light receiving port, and the intensity of light coupled to the light receiving port is acquired, and the intensity of light coupled to the light receiving port is obtained by a calculation unit (not shown). Based on the monitor contents, the measured value is calculated.

  Here, the signal light input to the optical signal monitoring device may be, for example, WDM (Wavelength Division Multiplexing) light that bundles wavelengths λp to λq.

  As shown in FIG. 2, a wavelength dispersion element 18 is arranged between the collimating lenses 12, 15-1 to 15-m and the optical element 13, so that the condensing position is different for each wavelength, and the phase pattern is different for each wavelength. May be settable. In FIG. 2, the wavelength dispersion element has diffraction performance in the direction perpendicular to the paper surface, and light may be irradiated to different positions in the paper surface perpendicular direction of the SLM 14 depending on the wavelength of the input light. The wavelength dispersion element 18 may be disposed between the optical element 13 and the SLM 14.

  Moreover, it is good also as a structure which monitors the optical signal for every core by connecting the core from which a multi-core fiber differs in the front | former stage of an input port. Further, there may be a configuration in which a plurality of input ports are present, a multimode fiber is disposed in the preceding stage, and each mode is connected to a separate input port, thereby monitoring an optical signal for each mode.

  1 and 2 show the case where one light receiving port is arranged for one input port, but a plurality of light receiving ports are provided for one input port as shown in FIG. It may be possible to select at an emission angle of. By arranging as shown in FIG. 3, it is possible to output to any single or multiple light receiving ports with any intensity / phase and delay time. In this case, it is possible to develop a function that the light receiving port can be shared by different input ports and wavelength channels by temporally switching the light receiving port.

  As shown in FIG. 4, signals from a plurality of input ports may be combined in the same region of the SLM 14. This configuration is effective for phase measurement of an optical signal as will be described later.

  As shown in FIG. 5, an optical coupler may be connected downstream of the light receiving port, and measurement may be performed by interfering between different light receiving ports. This configuration is effective for the OSNR monitor described later.

  As shown in FIG. 6, a band pass filter may be connected after the light receiving port to measure only a signal component having an arbitrary frequency. This configuration is effective for PMD and CD monitors using clock tone detection described later.

  Further, a transmissive SLM can be used instead of the reflective SLM 14 shown in FIGS. When a transmission type SLM is used, an equivalent function can be obtained by configuring the input side and output side optical systems symmetrically with respect to the y axis passing through the center of the SLM 14 in the configuration shown in FIGS. It can be expressed.

(Configuration of phase modulation element)
The SLM 14 used in the optical signal monitoring apparatus of this embodiment will be described in further detail. 7 and 8 are diagrams showing a configuration when the reflective SLM 14 is viewed from the z-axis direction. FIG. 7 shows a light irradiation region, and FIG. 8 shows a light irradiation region decomposed into wavelength channels. The SLM has p × q pixels arranged in a matrix on the xy plane, a large number of pixels 41-11 and 41-pq that independently control the phase of light in each pixel, and a driver that controls the phase of each pixel The element 42 and the reflection part 43 are provided on the back surface. The transmissive SLM 14 has a configuration in which the reflection part 43 on the back surface of FIGS.

  In the above optical signal monitoring device, the light irradiation region when light is incident on the SLM 14 is the region R shown in FIG. By giving a specific phase pattern to each pixel in the region R, the wavefront of the emitted light can be controlled, and the traveling direction of the emitted light and the light intensity / phase in that direction can be controlled. It is also possible to split the input light in multiple directions and output it. In addition, when the incident light is a WDM signal and is dispersed in the x-axis direction (for example, the direction perpendicular to the paper surface of FIGS. 2 and 4) by the diffraction grating, the incident area differs for each wavelength channel as shown in FIG. ~ Rn. In this case, by independently controlling the phase patterns of the regions R1 to Rn, it is possible to set different light receiving port selections, output light intensities / phases, and delay amounts for each wavelength channel.

  The SLM 14 can be realized using, for example, LCOS (Liquid Crystal On Silicon). In this element, the orientation direction of the liquid crystal material can be controlled by a voltage applied to the driver electrode, and thus the phase can be controlled by changing the refractive index of the liquid crystal felt by the input signal. A reflective phase modulator can be realized by using the front electrode as a transparent electrode and the back electrode as a reflective electrode. Further, by using both the front and back electrodes as transparent electrodes, a transmissive phase modulator can be realized. A material exhibiting an electro-optic effect may be used instead of the liquid crystal material.

  The SLM 14 can also be realized by using a MEMS (Micro Electro Mechanical System) mirror. For example, by applying a voltage, it is possible to change the optical path length for each pixel and to control the phase by displacing the mirror corresponding to the position of each pixel in the z-axis direction.

  In the optical signal monitoring apparatus described above, various measurements can be performed on the optical signal based on the light intensity acquired by the optical power monitor 17. For example, an optical channel monitor (OCM), OSNR monitor, PMD / CD monitor, and optical phase monitor can be used. These measurement methods will be described below.

(Optical channel monitoring method)
Next, a method for performing optical channel monitoring (OCM) in the optical signal monitoring apparatus of this embodiment having the above-described configuration will be described. Here, a method using the optical system shown in FIG. 3 will be described as an example. However, in any of the optical systems shown in FIGS. 1 to 6, the intensity of the optical channel can be monitored by the same method as described below.

Light intensity P of the input signal, for example, selects the optical fiber 16-1 as a single light receiving port, the losses due to coupling of the optical system at the time the received light intensity P _PD and port selection power monitoring at the optical fiber 16-1 The value α can be converted through the following equation.

In order to couple light to a single light receiving port, for example, a blazed phase pattern as shown in FIG. 9 may be applied. Since the value of the loss α can be held in advance by experiment or light propagation simulation, the value of the intensity P of the optical channel can be specified by monitoring _PPD .

  Further, when there are a plurality of light receiving ports for one input port as shown in FIGS. 5 and 6, for example, it is possible to measure different wavelength channels by that number. If the number of light receiving ports is smaller than the number of wavelength channels, for example, by changing the wavelength channel coupled to the light receiving port with time and recording the relationship between the time and wavelength, different wavelength channels can be received by the same light receiving port. It is possible to measure at the port. At this time, it is possible to remove influences other than the desired wavelength channel by applying a phase pattern to the SLM so that wavelength channels not to be measured are not coupled to the light receiving port. Thereby, since the number of light receiving ports can be reduced, it is possible to provide additional values such as downsizing and cost reduction of the system.

(OSNR monitoring method)
A method for performing OSNR monitoring in the optical signal monitoring apparatus of this embodiment will be described. First, a method for using the optical system shown in FIG. 5 will be described. A plurality of optical system OSNR monitors have been proposed. Here, an OSNR monitor method using a delay interferometer described in Non-Patent Document 2 will be described. Compared with other systems, this system has excellent characteristics such as in-band measurement, measurement regardless of the modulation signal format, and excellent polarization mode dispersion and chromatic dispersion tolerance. In general, a delay interferometer as shown in Non-Patent Document 2 requires a plurality of optical members such as a wavelength filter, a delay line, an optical phase sweep element, and an optical splitter. In the optical signal monitoring apparatus of this embodiment, these members are used. The functions of the delay interferometer that can be realized by the above can be realized with fewer members.

  FIG. 10 is a diagram showing an example of light coupling in the delay interferometer realized in the optical system shown in FIG. The light incident on the SLM 14 is branched into two and coupled to optical fibers 16-n and 16-n-1 which are different light receiving ports. At this time, the relative delay amount Δτ is generated because the optical path length passing through the path differs. By setting Δτ to a natural number multiple of one symbol period of the signal light or a natural number, an undesired beat component can be eliminated, and the measurement accuracy is improved. Further, the number of branches of light emitted from the SLM 14 may be two or more if not coupled to the light receiving port.

The signal lights coupled to the light receiving ports 16-n and 16-n-1 are respectively connected to different input ports of the optical coupler 19- (n / 2) to cause interference. Optical power monitors 17- (n-1) and 17-n are arranged at the subsequent stage of the optical coupler 19- (n / 2), and by measuring the respective intensities P _PD1 and P _PD2 , the delay interferometer It is possible to measure the interference light intensity. The relative phase difference φ between the two branched lights is swept by sweeping one phase of the two branched lights on the SLM 14 so that the ratio of the interference light intensity at each port is maximized. The OSNR can be calculated from the following equation using the intensity ratio R = P _PD1 / P _PD2 of each power monitor. (See Non-Patent Document 2)

  In the above equation (2), s and n are values of R when there is no optical noise and when there is no optical signal, and NEB is an effective transmission band of the noise component. By calibrating s and n in advance, the NEB can be calculated from the width of the transmission band set by the SLM. Therefore, the OSNR can be estimated by monitoring the above-mentioned R.

  A phase pattern for splitting light into a plurality of paths and sweeping the relative phases thereof can be obtained using CGH (Computer Generated Hologram), and frequency modulation described in Patent Document 2 can be used. This can be realized, for example, by superposing sin waves with different frequencies on a sawtooth wave as described in FIG. The relative phase difference can be swept by changing the phase value of the sin wave. The superimposed wave (phase pattern) can exhibit the same function if it has periodicity such as a sawtooth wave and a triangular wave as well as a sin wave. By controlling the amplitude of the superimposed wave, a desired optical phase change can be given to the incident wave. Further, it can also be realized by dividing a region on the SLM to which the incident beam is coupled as shown in FIG. 12 and applying a different phase pattern to each.

  Next, a technique for performing OSNR monitoring using the optical system shown in FIG. 3 will be described. In addition, any of the optical systems shown in FIGS. 1 to 6 can perform OSNR monitoring by the same method as described below. FIG. 13 shows an optical configuration when the optical system of FIG. 3 is viewed from the y-axis direction. In FIG. 13, for convenience, the input side and the light receiving side are shown as the same configuration. In this configuration, the two beams branched on the SLM 14 are set so that the emission angles are slightly different so that they are combined at the same light receiving port 16 after being given an optical path difference, so that interference light can be measured without a coupler. Is possible.

  The light receiving port 16 is coupled with a relative delay amount Δτ according to the optical path difference between the branched optical signals, thereby forming a delay interferometer. By setting Δτ to a natural number multiple of the 1-bit period of signal light or a natural number, it is possible to eliminate an undesired beat component and improve measurement accuracy. Further, the number of branches of light emitted from the SLM 14 may be two or more if not coupled to the light receiving port. An optical power monitor 17 is disposed after the light receiving port, and the optical monitor intensity Pmax at which the power monitor intensity is maximized and the intensity Pmin at which the power monitor is minimized are swept while sweeping the relative phase difference φ of the light bifurcated on the SLM 14. And the ratio R = Pmax / Pmin is obtained, and the OSNR can be calculated from the equation (2). Compared with the OSNR monitor configuration described above, this configuration provides an excellent effect of reducing the number of parts.

  3 and 5, when there are a plurality of light receiving ports for one input port, for example, it is possible to measure different wavelength channels by that number. If the number of light receiving ports is smaller than the number of wavelength channels, for example, by changing the wavelength channel coupled to the light receiving port with time and recording the relationship between the time and wavelength, different wavelength channels can be received by the same light receiving port. It is possible to measure at the port. At this time, it is possible to remove influences other than the desired wavelength channel by applying a phase pattern to the SLM so that wavelength channels not to be measured are not coupled to the light receiving port. Thereby, since the number of light receiving ports can be reduced, it is possible to provide additional values such as downsizing and cost reduction of the system.

(PMD / CD monitor)
Next, a method for monitoring PMD and CD in the optical signal monitoring apparatus of FIG. 6 will be described. A plurality of methods have been proposed for PMD and CD monitor. Here, a method of monitoring PMD and CD from a clock tone using a delay interferometer described in Non-Patent Document 3 can be adopted. Compared with other systems, this system has excellent features such as measurement capability regardless of the modulation signal format and simple optical configuration.

  The delay interferometer that monitors PMD and CD from the clock tone can be realized by the configuration of FIG. 6 in which the band-pass filter 20 is arranged after the light receiving port of the optical signal monitoring device having the optical configuration shown in FIG. . PMD and CD can be monitored by extracting a clock tone of a predetermined frequency by the band pass filter 20 and measuring the signal intensity of the extracted clock tone. The clock tone intensity varies depending on the occurrence of PMD and CD. Therefore, the correlation between the clock tone intensity and the generation level of PMD and CD is measured in advance, the correlation is held as a calibration line, and PMD and CD corresponding to the clock tone intensity measured based on the calibration line are stored. By specifying, PMD and CD can be monitored.

  In the configuration shown in FIG. 13 described in the OSNR monitoring method in order to measure interference light without a coupler in the optical signal monitoring apparatus of FIG. 6, a bandpass filter 20 is provided between the light receiving port 16 and the optical power monitor 17. The intensity of the clock tone signal is measured with the arrangement of In this configuration, the two beams branched on the SLM 14 are set so that the emission angles are slightly different so that they are combined at the same light receiving port 16 after being given an optical path difference, so that interference light can be measured without a coupler. Is possible.

  The light receiving port 16 is coupled with a relative delay amount Δτ according to the optical path difference between the branched optical signals, thereby forming a delay interferometer. By setting Δτ to a natural number multiple of the 1-bit period of signal light or a natural number, it is possible to eliminate an undesired beat component and improve measurement accuracy. Further, the number of branches of light emitted from the SLM 14 may be two or more if not coupled to the light receiving port.

  In addition, when there are a plurality of light receiving ports for one input port as shown in FIG. 6, for example, it is possible to measure different wavelength channels by the number. If the number of light receiving ports is smaller than the number of wavelength channels, for example, by changing the wavelength channel coupled to the light receiving port with time and recording the relationship between the time and wavelength, different wavelength channels can be received by the same light receiving port. It is possible to measure at the port. At this time, it is possible to remove influences other than the desired wavelength channel by applying a phase pattern to the SLM so that wavelength channels not to be measured are not coupled to the light receiving port. Thereby, since the number of light receiving ports can be reduced, it is possible to provide additional values such as downsizing and cost reduction of the system.

(Optical phase monitor)
A method for performing optical phase monitoring in the optical signal monitoring apparatus of this embodiment will be described. Here, a case where optical phase monitoring is performed using the optical system of FIG. 3 will be described as an example. The optical phase monitor generally adopts a 90 ° hybrid configuration, and a method for performing measurement equivalent to that of the 90 ° hybrid by using the SLM 14 will be described below.

  FIG. 14 shows an example in which the phase modulation element SLM is controlled so as to realize a 90 ° hybrid in the optical system of FIG. An optical signal P ′ (optical path indicated by a solid line) and a measured optical signal P (optical path indicated by a broken line), which serve as a phase reference, are incident from different input ports and branched into three on the SLM. One of the branched signals is controlled to be coupled to the light receiving port A for each of the optical signals P and P ′, and one signal different from the signal coupled to the light receiving port A is applied to the optical signals P and P ′. Are coupled to the light receiving port B one by one. The remaining branch signal need not be coupled to the light receiving port. At this time, the optical phase difference Δφ between the two lights coupled to the light receiving ports A and B is set with respect to either one of the optical signals P and P ′.

  Since the light receiving ports A and B each operate as a delay line interferometer, the light intensity varies according to the relative phase difference Δθ caused by the optical path length difference between P and P ′. At this time, the intensity of the signal light at the light receiving ports A and B varies as shown in FIG. 15 with respect to Δθ. As can be seen from FIG. 15, since the received light intensity of each port is shifted by ΔΨ, the phase value can be uniquely determined by observing both light intensity values. In order to split the light into three, for example, the above-described sin wave superposition, region division, use of CGH, and the like can be considered.

  Further, when there are a plurality of light receiving ports for one input port as shown in FIG. 3, it is possible to measure, for example, different wavelength channels corresponding to the number of light receiving ports. If the number of light receiving ports is smaller than the number of wavelength channels, for example, by changing the wavelength channel coupled to the light receiving port with time and recording the relationship between the time and wavelength, different wavelength channels can be received by the same light receiving port. It is possible to measure at the port. At this time, it is possible to remove influences other than the desired wavelength channel by applying a phase pattern to the SLM so that wavelength channels not to be measured are not coupled to the light receiving port. Thereby, since the number of light receiving ports can be reduced, it is possible to provide additional values such as downsizing and cost reduction of the system.

(Programmable monitor)
For example, if the optical signal monitoring apparatus having the optical system configuration shown in FIG. 6 is used, the monitoring function of OCM, OSNR, PMD, and CD can be arbitrarily changed from the above method only by changing the phase pattern on the SLM 14. . Since the phase pattern of the SLM 14 can be changed from the outside in a programmable manner, desired characteristics can be flexibly monitored according to the needs of the time. As a result, for example, when designing a circuit, OSNR and GD are monitored and applied to a budget design for optical signal quality. During operation, a certain threshold value that degrades optical signal quality using a PMD monitor or OSNR monitor is not exceeded. It is possible to monitor, and at the time of failure analysis, it is possible to specify a link disconnection location by OCM, etc., which contributes to advancement of circuit design, high reliability of maintenance operation, efficiency improvement of failure analysis, and the like.

  In the optical signal monitoring apparatus of the present embodiment, the reflection type SLM (Spatial Light Modulator) is controlled to output to any path with any intensity / phase and delay time. An optical monitor device capable of programmably changing the optical monitor function is provided. Further, according to the optical signal monitoring apparatus of the present embodiment, it is possible to extract and monitor optical signals of arbitrary wavelength channels and input cores, and it is also possible to provide different monitoring functions for each wavelength channel and for each input core. is there.

[Second Embodiment]
The optical switch integrated optical signal monitoring device of this embodiment has a configuration in which an optical switch is combined with the optical signal monitoring device that realizes the monitoring function described in the first embodiment. The optical switch integrated type optical signal monitoring device of this embodiment branches an input signal by an optical coupler, and couples the branched optical signal to an input of the optical signal monitoring device and an input of the optical switch.

  16 and 17 are diagrams illustrating a configuration example of an optical switch integrated optical signal monitoring device using the reflective SLM of the present embodiment. However, the direction in which the input and light receiving ports are arranged is the y-axis, and the direction in which the optical signal propagates is the z-axis.

  In the optical switch integrated type optical signal monitoring device, an optical signal incident from an input port 21 is branched by an optical coupler 22 and connected to input optical fibers 23 and 24 for an optical switch and an optical signal monitor, respectively. The respective optical signals are emitted into the space and given to the optical element 27 via the collimating lenses 25 and 26.

  The outgoing light from the optical element 27 is reflected by the SLM 28 and again passes through the optical element 27 to collimate lens arrays 29-1 to 29-n ′ and 30-1 to 30-n, and an optical fiber 31 that is an output port and a light receiving port. -1 to 31-n 'and 32-1 to 32-n. The optical signal on the output port side of the optical switch layer is output as it is from the output port. Optical power monitors 33-1 to 33-n are connected downstream of the light receiving port for optical monitoring, and light coupled to the light receiving port can be monitored. Here, the optical intensity, optical phase, and delay time of the optical signal are selected based on the phase pattern given to the SLM 28.

  As the optical element 27, means for changing the emitting direction of the signal light so as to emit the input light toward the SLM can be used, and for example, a lens, a prism, a reflecting mirror, or a diffraction grating can be used. The input signal light may be, for example, WDM light that bundles wavelengths λp to λq.

  Further, as shown in FIG. 17, a wavelength dispersion element 34 may be arranged between the collimating lens and the optical element so that the condensing position is different for each wavelength, and a different phase pattern can be set for each wavelength. In FIG. 17, the wavelength dispersive element has diffraction performance in the direction perpendicular to the paper surface, and light may be irradiated to different positions in the paper surface perpendicular direction of the SLM depending on the wavelength of the input light. The wavelength dispersion element 34 may be disposed between the optical element 27 and the SLM 28. Moreover, it is good also as a structure which monitors the optical signal for every core by connecting the core from which a multi-core fiber differs in the front | former stage of an input port. Also, there may be a configuration in which a plurality of input ports are present, a multimode fiber is arranged in the previous stage, and each mode is connected to each input port, thereby monitoring the optical signal for each mode.

  16 and 17 show the case where one light receiving port is arranged one by one, but a plurality of light receiving ports may be selectable by the emission angle from the SLM 28 as in the first embodiment. Thereby, it is possible to output to any single or plural light receiving ports with any intensity / phase and delay time. In this case, it is possible to develop a function that the light receiving port can be shared by different input ports and wavelength channels by temporally switching the light receiving port. Further, signals from a plurality of input ports may be combined in the same region of the SLM. This configuration is effective for the phase measurement of the optical signal described above.

  Alternatively, an optical coupler may be connected downstream of the light receiving port, and measurement may be performed by causing interference between different light receiving ports. This is effective for the OSNR monitor as described above. Alternatively, a band pass filter may be connected after the light receiving port to measure only a signal component having an arbitrary frequency. This is effective for PMD and CD monitors as described above. The SLM may be a transmissive type. In this case, for example, if the optical system is arranged in line symmetry with respect to the y-axis passing through the center of the SLM, an equivalent function can be exhibited. The same optical monitoring technique as that of the first embodiment may be used.

  The optical switch integrated type optical signal monitoring apparatus according to the present embodiment can integrate the optical switch device including the wavelength selective switch and the optical signal monitoring apparatus in the same optical system. It is possible to integrate a large number of monitoring functions in each optical node while suppressing.

11 Optical fiber 12 Collimating lens 13 Optical element 14 SLM
15 Collimating lens array 16 Optical fiber 17 Optical power monitor 18 Wavelength dispersion element 41 Pixel 42 Driver element

Claims (8)

An input port for inputting the optical signal to be monitored;
A plurality of pixels arranged in a matrix in a plane and a drive unit that drives the pixels, and the phase pattern of the plurality of pixels is controlled by the drive unit, and the optical phase of the signal light input to each pixel A spatial light modulator that emits light by changing
An optical element that converts the angle and position of the output light of the signal light so that the signal light emitted to the space from the input port irradiates the spatial light modulation element;
A light receiving port to which light emitted from the spatial light modulator is coupled;
A light receiving element for measuring the intensity of light coupled to the light receiving port;
Calculation means for calculating a measurement value according to the monitor content of the optical signal based on the intensity of light measured by the light receiving element;
The spatial light modulator controls so that an optical signal input from the input port is optically coupled to a single light receiving port, and the calculating means includes the intensity of light measured at the light receiving port and the light intensity measured by the light receiving port. An optical signal monitoring device that calculates the intensity of the input optical signal based on a loss value α of the optical system when coupled to the light receiving port . An input port for inputting the optical signal to be monitored;
A plurality of pixels arranged in a matrix in a plane and a drive unit that drives the pixels, and the phase pattern of the plurality of pixels is controlled by the drive unit, and the optical phase of the signal light input to each pixel A spatial light modulator that emits light by changing
An optical element that converts the angle and position of the output light of the signal light so that the signal light emitted to the space from the input port irradiates the spatial light modulation element;
A light receiving port to which light emitted from the spatial light modulator is coupled;
A light receiving element for measuring the intensity of light coupled to the light receiving port;
Calculation means for calculating a measurement value according to the monitor content of the optical signal based on the intensity of light measured by the light receiving element;
The spatial light modulation element branches an emitted optical signal in n (n is an integer of 2 or more) direction or more, and gives a different time delay amount τ _n to each of the n branched optical signals. A delay interferometer is formed by coupling at least two of the branched optical signals to the same light receiving port, and the optical phase of at least one of the branched signals is changed from 0 to 2π. The light receiving element measures the light receiving intensity of the light whose interference light intensity has changed, and the calculating means records and records the maximum value and the minimum value of the light receiving intensity. An optical signal monitoring device that calculates an OSNR from a ratio between a maximum value and a minimum value. An input port for inputting the optical signal to be monitored;
A plurality of pixels arranged in a matrix in a plane and a drive unit that drives the pixels, and the phase pattern of the plurality of pixels is controlled by the drive unit, and the optical phase of the signal light input to each pixel A spatial light modulator that emits light by changing
An optical element that converts the angle and position of the output light of the signal light so that the signal light emitted to the space from the input port irradiates the spatial light modulation element;
A light receiving port to which light emitted from the spatial light modulator is coupled;
A light receiving element for measuring the intensity of light coupled to the light receiving port;
Calculation means for calculating a measurement value according to the monitor content of the optical signal based on the intensity of light measured by the light receiving element;
The light receiving element has a band pass filter for filtering light coupled to the light receiving port;
The spatial light modulation element branches an emitted optical signal in n (n is an integer of 2 or more) direction or more, and gives a different time delay amount τ _n to each of the n branched optical signals. A delay interferometer is formed by coupling at least two of the branched optical signals to the same light receiving port, and the optical phase of at least one of the branched signals is changed from 0 to 2π. changing the interference light intensity by the light receiving element, said light interference light intensity changes with more filtering to the band-pass filter to measure the received light intensity of the clock tone signal, said calculation means, said An optical signal monitoring device that records a maximum value and a minimum value of received light intensity, and calculates a chromatic dispersion amount and / or a polarization mode dispersion from a ratio between the recorded maximum value and minimum value. 4. The optical signal monitoring apparatus according to claim 2 , wherein the time delay amount τ _n is a natural number multiple of a 1-bit length of an optical signal or a natural fraction. 5. An input port for inputting the optical signal to be monitored;
A plurality of pixels arranged in a matrix in a plane and a drive unit that drives the pixels, and the phase pattern of the plurality of pixels is controlled by the drive unit, and the optical phase of the signal light input to each pixel A spatial light modulator that emits light by changing
An optical element that converts the angle and position of the output light of the signal light so that the signal light emitted to the space from the input port irradiates the spatial light modulation element;
A light receiving port to which light emitted from the spatial light modulator is coupled;
A light receiving element for measuring the intensity of light coupled to the light receiving port;
Calculation means for calculating a measurement value according to the monitor content of the optical signal based on the intensity of light measured by the light receiving element;
The input port has an optical signal input port for inputting an optical signal to be measured, and a reference optical signal input port for inputting a reference optical signal serving as a reference for an optical phase, and the light receiving port is a first light receiving port. And a second light receiving port,
The spatial light modulation element branches an input optical signal and a reference optical signal into two or more directions, respectively, and at least one of the branched optical signal and the reference optical signal is supplied to the first light receiving port. Combining at least one of the remaining branched optical signal and the reference optical signal to the second light receiving port;
The spatial light modulator sets the phase so that the optical phase of either the optical signal coupled to the second light receiving port or the reference optical signal differs from the signal coupled to the first light receiving port by Δφ. and said calculating means, and calculates the relative optical phase of the optical signal and the reference light signal from the value of the light intensity in the first light receiving port and the second receiving port, an optical signal monitor apparatus. The optical element includes a wavelength dispersion element that couples to a different position on the spatial light modulation element for each wavelength of the input optical signal, and the spatial light modulation element includes only an arbitrary wavelength channel as a light receiving port. 6. The optical signal monitoring apparatus according to claim 1, wherein an optical signal of an arbitrary wavelength channel is extracted and monitored by controlling the phase pattern so as to be coupled. The spatial light modulator, by varying the input port or wavelength channel is coupled temporally, characterized thereby sharing one receiving port for a plurality of input ports, one of claims 1 to 6 or optical signal monitoring apparatus according to item 1. An optical signal monitoring device according to any one of claims 1 to 7 ,
An optical switch,
An optical switch integrated optical signal monitoring device comprising: an optical coupler that branches an input optical signal so as to be input to either the optical signal monitoring device or the optical switch.