JP2020141321A - Phase reproduction type optical synchronous detector - Google Patents

Abstract

To provide an optical detection system for reproducing optical phase information with a simple configuration.SOLUTION: A system for receiving an optical signal and detecting information including an optical phase, includes: interference element 3 for scattering the optical signal and causing interference; a detector array 7 including a plurality of detectors 5 for measuring light intensity of an optical signal interfered by an interference element; and a processing circuit 9 for recovering phase information of the optical signal using information about the light intensity measured by the detector array.SELECTED DRAWING: Figure 1

Description

The present invention relates to a system or method for receiving an optical signal and detecting information including an optical phase. More specifically, the present invention is a system capable of reproducing the optical phase information of an optical signal by causing interference in the optical signal and applying phase retrieval technology based on the observation result of the optical signal intensity after the interference. Regarding the method.

In today's polarization-diversified optical coherent receivers, which are widely used in backbone optical communication networks, polarized beam splitters for separating polarized multiplex signals and local light for synchronous detection, An optical 90-degree hybrid for optical IQ mixing composed of complicated optical elements and the like is required as an optical preprocessing circuit. In addition, in the large-capacity optical space multiplex transmission method using multiple fiber modes, these optical preprocessing circuits are required for the number of spatial channels, and an additional optical system for spatial channel separation is required. Become.

In the next-generation optical coherent reception technology, spatial expandability for optical spatial multiplex transmission and simplification for application to access networks are newly required.

K. Kikuchi, “Fundamentals of coherent optical fiber communications,” J. et al. Lightwave Technology. , Vol. 34, no. 1, pp. 157-179, 2016.

An object of the present invention is to provide a system or method that recovers optical phase information by a simplified device configuration and enables coherent reception.

The present invention basically provides a system or method based on a new coherent reception technique based on a phase retrieval technique. This system uses a direct detector array consisting of a large number of elements with more than the number of optical signal channels, and performs spatially redundant observations to recover the optical phase information lost by direct detection in a signal processing manner. As a result, batch coherent reception of optical space multiplex signals can be realized without complicated optical preprocessing.

In other words, the system of the present invention does not extract the optical electric field phase by interference with local emission (heterodyne or homodyne), but from, for example, fluctuation of light intensity due to spatiotemporally random interference between phase-modulated signal lights. ， Reproduces optical electric field information including phase in signal processing.

One of the embodiments described in this specification relates to a system 1 for receiving an optical signal and detecting information including an optical phase.
The system 1 includes an interference element 3, a detector array 7 including a plurality of detectors 5, and a processing circuit 9.
The interference element 3 is an element for scattering an optical signal and causing interference.
The detector 5 is an element for measuring the light intensity of an optical signal in which interference is caused by the interference element 3.
The processing circuit 9 is an element for recovering the phase information of the optical signal by using the information on the light intensity measured by the detector array 7.

In one aspect of the above system, the interfering element 3 causes random interference in the optical signal.

In one aspect of the above system, where the number of the plurality of detectors 5 is Nr and the number of channels of the optical signal is Nt, Nr is four times or more of Nt.

In one aspect of the above system, the processing circuit 9 recovers the phase information of the optical signal using elements related to the discreteness of the optical signal.

In one aspect of the above system, the processing circuit 9 infers an element related to the randomness of the interfering element 3 using a known signal, and uses the inferred element related to the randomness of the interfering element 3 to provide phase information of the optical signal. Is to recover.

One of the embodiments described in this specification is a method for receiving an optical signal and detecting information including an optical phase.
In this method, the interference element 3 scatters the optical phase modulation signal to cause interference (S101).
A step (S102) in which the detector array 7 including the plurality of detectors 5 measures the light intensity of the optical signal in which interference is caused by the interference element 3
The processing circuit 9 includes a step (S103) of recovering the phase information of the optical signal by using the information on the light intensity measured by the detector array 7.

The present invention can provide a system and a method that recovers optical phase information and enables coherent reception by a simplified device configuration. The system of the present invention functions as a phase-retrieving coherent receiver, has a simple configuration, and has excellent spatial expandability. Therefore, light to areas closer to the user such as metro-access network, optical space communication, and optical sensing. It is expected to accelerate the development of coherent technology.

FIG. 1 is a block diagram showing a basic configuration example of the system of the present invention. FIG. 2 is a diagram for explaining the principle of the present invention. FIG. 3A is a conceptual diagram showing a configuration example of the system in the embodiment. FIG. 3B is an enlarged view of a 32-pixel two-dimensional PD array portion. FIG. 4 is a graph that replaces the drawing showing an example of estimating the channel response. Figure 5 illustrates different for N _r, the bit error rate for (BER) characteristics, the number of iterations N of the weighted steepest descent type phase recovery algorithm considering discreteness of the signal (DRAF) of the case of a single transmission channel It is a graph that replaces the drawing. FIG. 6 is a graph that replaces the drawing showing the bit error rate (BER) characteristic vs. the number of iterations N of DRAF for different N _{r in} the case of two-channel spatial multiplexing transmission.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. The present invention is not limited to the forms described below, and includes those which are appropriately modified by those skilled in the art from the following forms to the extent obvious to those skilled in the art.

FIG. 1 is a block diagram showing a basic configuration example of the system of the present invention. As shown in FIG. 1, the system 1 includes an interference element 3, a detector array 7 including a plurality of detectors 5, and a processing circuit 9. This system 1 relates to a system for receiving an optical signal and detecting information including an optical phase included in the optical signal.

An example of an optical signal is a phase-modulated signal that has phase as information. Specific examples of optical signals are optical QAM (quadrature phase amplitude modulation) signals, optical PSK (phase shift keying) signals, and optical OFDM (orthogonal frequency division multiplexing) modulation signals. Examples of optical PSK (Phase Shift Keying) signals are Optical Two Phase Phase Shift Keying (BPSK) Signals, Optical Four Phase Phase Shift Keying (QPSK) Signals, and Optical Amplitude Phase Shift Keying (APSK) Signals. An example of information including the optical phase is a modulated signal carried on these optical signals. The optical signal preferably has a high data transmission rate. An example of the data transmission speed is 1 Gbps or more and 100 Tbps or less, and may be 10 Gbps or more and 100 Tbps or less, or 50 Gbps or more and 50 Tbps or less. The optical signal is preferably via an optical fiber or free space in order to support high-speed data communication.

The interference element 3 is an element for scattering an optical signal and causing interference. The interference element 3 is not particularly limited as long as it is an element capable of scattering an optical signal and causing interference. Due to the interference element 3, the optical signals interfere with each other randomly, for example, temporally and spatially. The interference element 3 may be an optical element or an element including an optical element. Examples of the interfering element 3 are multimode fiber, spatial light modulators, holography plates, diffusers, and optical integrated circuits. When the communication path itself of the optical signal causes interference, the communication path itself may function as the interference element 3. The interference element 3 is preferably one that causes random interference in the optical signal. Scattering means that an optical signal travels in multiple directions. Random interference also means that the same interference does not occur in all optical signals.

The detector 5 is an element for measuring the light intensity of an optical signal in which interference is caused by the interference element 3. The plurality of detectors 5 receive fluctuations in light intensity temporally and spatially due to the interference element 3. An example of the detector 5 is a high-speed photodetector (PD: Photodetector). The photodetectors are preferably integrated. Assuming that the number of the plurality of detectors 5 is Nr and the number of optical signal channels is Nt, Nr is preferably 4 times or more of Nt, Nr may be 4 times Nt + 1 or more, and Nr is It may be 6 times or more of Nt, and Nr may be 8 times or more of Nt. However, if the number of detectors becomes enormous, the apparatus becomes complicated, so Nr may be 50 times or less, 10 times or less, or 8 times or less of Nt. In this way, by using a direct detector array consisting of a large number of detectors and performing spatially redundant observations, the optical phase information lost by the direct detection can be recovered by signal processing. This makes it possible to realize batch coherent reception of spatial multiplex signals without complicated optical preprocessing.

The processing circuit 9 is an element for recovering the phase information of the optical signal by using the information on the light intensity measured by the detector array 7. The processing circuit may be implemented by hardware alone or by using hardware and software for quick processing. The software may be a program for performing a predetermined process. The processing circuit 9 receives information on a set of optical electric field strength information from a plurality of detectors 5, and reproduces the phase information of the optical signal in a signal processing manner by, for example, a phase retrieval method. As described above, a method of causing interference in a signal and reproducing (recovering) the phase information of the original optical signal from a plurality of interference signals is known. Therefore, the processing circuit 9 may implement a known phase retrieval algorithm to recover the phase information of the optical signal. Specific phase retrieval algorithms include iterative error correction methods such as the Gerchberg-Saxton method, semidefinite programming methods such as PhaseLift, non-convex optimization methods such as the Wizard flow, alternating direction methods of multipliers (ADMM) and approximations. It is a convex optimization method such as message propagation (AMP).

At this time, the optical signal is subjected to discrete modulation such as binary (0, π) and tetravalence (0, π / 2, π, 3π / 2). Therefore, it is preferable that the processing circuit 9 recovers the phase information of the optical signal by using the element related to the discreteness of the optical signal. When reproducing the optical phase information, it is desirable to receive information on the modulation mode of the optical signal, estimate the phase according to the modulation mode, and then recover the phase information. For example, when the optical signal is a binary (0, π) phase-modulated signal, the phase of the optical signal is 0 or π, so that it is either of them when reproducing the phase information. With knowledge, the accuracy and robustness of phase information reproduction can be improved. In this way, by recovering the phase information of the optical signal by using the element related to the discreteness of the optical signal, the amount of signal processing can be significantly reduced and the phase information of the optical signal can be recovered quickly.

It is preferable that the processing circuit 9 recovers the phase information of the optical signal by using the element related to the randomness of the interference element 3. As the element related to the randomness of the interference element 3, a known signal may be used to obtain an element related to the randomness of the interference element 3, and the obtained element may be used as an estimated value.

Scattering and interference by the interference element 3 are not always constant but change. Therefore, the influence (randomness) of the interference element 3 on the optical signal changes. Therefore, when the known signal is used to cause diffusion or interference by the interference element 3, the detector array 7 detects the set of interference light intensities, and the processing circuit 9 recovers the phase information of the optical signal, the optical signal is obtained. Since the phase information of is known, the influence (randomness) of the interference element 3 can be obtained. The randomness of the interference element 3 may vary between when a known signal is used and when an actual signal light is used, but it relates to the randomness of the interference element 3 obtained by using the known signal. By reproducing the phase information of the signal light using the element, the phase information can be recovered more quickly.

Next, a method of detecting information including the optical phase using the above system will be described.
The optical signal is transmitted to the interference element 3 via the optical transmission line. The optical transmission line itself may function as an interference element. The interference element 3 scatters the optical phase modulation signal, and the scattered optical signal causes interference (S101).
The detector array 7, which includes the plurality of detectors 5, measures the light intensity of the optical signal in which interference is caused by the interference element 3 (S102). Specifically, the intensity of the optical signal received by each of the plurality of detectors 5 is measured. Then, the detector array 7 outputs the intensity information of the optical signals from the plurality of detectors 5 to the processing circuit 9.
The processing circuit 9 recovers the phase information of the optical signal by using the information on the plurality of light intensities measured by the detector array 7 (S103). Using this recovered phase information, the information carried on the optical signal may be analyzed and output as appropriate.

が，Ｎ_ｒ個のＰＤ素子により検波されたとする。すると，環境雑音がないと仮定した場合の，時間ｔにおける第ｊ番目のＰＤの出力振幅

は，式（１）で与えられる。

ここで，

は，第ｉ番目の送信器と第ｊ番目のＰＤとの間のチャネルのインパルス応答を示す。ここで，Ｄは，チャネル遅延広がり（ｃｈａｎｎｅｌ ｄｅｌａｙ ｓｐｒｅａｄ）を示し，

である。 Theoretical Theory The following is an explanation of a principle example of the phase reproduction method of the present invention. The present invention is not limited to the following examples. FIG. 2 is a conceptual diagram showing an example of the system of the present invention. In FIG. 2, the _Nt channel optical space multiplexing signal

But the is detected by the N _r number of PD elements. Then, assuming that there is no environmental noise, the output amplitude of the jth PD at time t

Is given by equation (1).

here,

Indicates the impulse response of the channel between the i-th transmitter and the j-th PD. Here, D indicates a channel delay spread, and D indicates a channel delay spread.

Is.

ここで，

であり，

は，

からなるブロックテプリッツ行列であり，

である。 For the sake of simplicity, equation (1) can be expressed as the following equation (2) when expressed using vectors and matrices.

here,

And

Is

It is a block Toeplitz matrix consisting of

Is.

のように表記する。 For the sake of simplicity,

Notated as.

Coherent detection of the optical signal x is equivalent to solving the simultaneous quadratic equations of Eq. (2). This type of problem is known as a (generalized) phase retrieval problem in many fields of science and engineering, such as X-ray analysis and scattering imaging (Y. Shechtman et al., IEEE Signal Process. Mag. , 32 (3), 87 (2015).

個の強度情報により

を正確に再構成するのに十分であることが指摘されている（［Ａ． Ｃｏｎｃａ ｅｔ ａｌ．， Ａｐｐｌ． Ｃｏｍｐｕｔ． Ｈａｒｍｏｎ． Ａｎａｌ．， ３８（２）， ３４６ （２０１５））。ゲルヒベルク・ザクストンやＰｈａｓｅＬｉｆｔ法（Ｋ． Ｊａｇａｎａｔｈａｎ， ｉｎ； Ｏｐｔｉｃａｌ Ｃｏｍｐｒｅｓｓｉｖｅ Ｉｍａｇｉｎｇ， ＣＲＣ， ２６３ （２０１５）．）といった，従来のＰＲアルゴリズムの多くは，計算量が大きく，高速通信システムへの応用には適さない。一方，近年，低要求演算量のアルゴリズムとして，非凸最適化手法に基づく手法が提案された（Ｅ． Ｊ． Ｃａｎｄｅｓ ｅｔ ａｌ， ＩＥＥＥ Ｔｒａｎｓ． Ｉｎｆ． Ｔｈｅｏｒｙ， ６１（４）， １９８５ （２０１５）． Ｇ． Ｗａｎｇ ｅｔ ａｌ．， ＩＥＥＥ Ｔｒａｎｓ． Ｓｉｇｎａｌ Ｐｒｏｃｅｓｓ．， ６６（１１）， ２８１８ （２０１８）．）この手法においては，式 （２）を直接解くのではなく，下記式（３）のように，損失関数を最小化することを考える。 In those areas,

By individual strength information

It has been pointed out that it is sufficient to accurately reconstruct ([A. Conca et al., Apple. Comput. Harmon. Anal., 38 (2), 346 (2015)). Many of the conventional PR algorithms, such as Gerchberg-Saxton and the PhaseLift method (K. Jaganathan, in; Optical Comprehensive Imaging, CRC, 263 (2015)), are computationally intensive and unsuitable for application to high-speed communication systems. .. On the other hand, in recent years, a method based on a non-convex optimization method has been proposed as an algorithm with a low demand calculation amount (EJ Candes et al, IEEE Trans. Inf. Theory, 61 (4), 1985 (2015). G. Wang et al., IEEE Trans. Signal Process., 66 (11), 2818 (2018).) In this method, instead of directly solving equation (2), the following equation (3) is used. Consider minimizing the loss function.

ここで，

は，重みベクトルであり，｜｜・｜｜は，ユークリッドノルムを示し，

は， 要素ごとの積（アダマール積）を示す。式（３）で示される損失関数は，凸関数ではなく，また滑らかでもないが，ｗを適切に選ぶことによって広義の勾配を導き出すことができる（Ｅ． Ｊ． Ｃａｎｄｅｓ ｅｔ ａｌ， ＩＥＥＥ Ｔｒａｎｓ． Ｉｎｆ． Ｔｈｅｏｒｙ， ６１（４）， １９８５ （２０１５），Ｇ． Ｗａｎｇ ｅｔ ａｌ．， ＩＥＥＥ Ｔｒａｎｓ． Ｓｉｇｎａｌ Ｐｒｏｃｅｓｓ．， ６６（１１）， ２８１８ （２０１８）．）。

here,

Is a weight vector, and || and || indicate the Euclidean norm.

Indicates the product of each element (Hadamard product). The loss function represented by the equation (3) is neither a convex function nor a smooth function, but a gradient in a broad sense can be derived by appropriately selecting w (EJ Candes et al, IEEE Transfer Inf Theory, 61 (4), 1985 (2015), G. Wang et al., IEEE Transfers. Signal Process., 66 (11), 2818 (2018).).

式（４）を用いることにより，式（３）を

（ここでμ_ｎはステップサイズである。）で示される最急降下法により，効率的に最小化できる。このアルゴリズムは，Ｒｅｗｅｉｇｈｔｅｄ Ａｍｐｌｉｔｕｄｅ Ｆｌｏｗ（ＲＡＦ）として知られている． That is,

By using equation (4), equation (3) can be obtained.

(Here, μ _n is the step size.) It can be minimized efficiently by the steepest descent method shown by. This algorithm is known as the Reviewed Amplitude Flow (RAF).

を送信することを考える。すると式（１）及び（２）は，以下のＮ_ｒ個の並列した位相回復問題として表現できる。 In deriving the phase retrieval algorithm described above, it was implicitly assumed that the observation matrix H was known. However, in a real system, H also needs to be estimated only from the amplitude information. K independent pilot series

Consider sending. Then, equations (1) and (2) can be expressed as the following _Nr parallel phase retrieval problems.

ここで，

である。 That is,

here,

Is.

Therefore, the channel h _j for each detector can be estimated by solving each phase recovery problem using the known detection matrix P. Incidentally, although between h _i and h _{j (i} ≠ _j) there is a phase ambiguity, the loss function used for signal detection l; no effect on (x w).

On the other hand, while many of the existing phase retrieval algorithms including the above-mentioned RAF have been proposed on the premise of random observation, it is not always easy to realize sufficiently random observation in a realistic system. As a result, the observation matrix H often has a specific structure. As described above, in optical space multiplex transmission, H is modeled as a Toeplitz matrix representing the response of a linear convolution communication path. It is known that the phase retrieval problem in which such an observation matrix has a specific structure requires more severe observations and requirements for the recovery algorithm than the phase retrieval problem based on random observation. ([Q. Qu et al., ArXiv: 1712.00716 (2017).). Therefore, in order to solve this problem, it is useful to use known information on the modulation method of optical signals. Here, we propose a RAF that considers the discreteness of the elements of the signal vector x by using the absolute value sum (SOAV) optimization method (M. Nagahara, IEEE Signal Process. Lett., 22 (10), 1575). (2015).).

を変調信号の組とすると，離散性を考慮した損失関数

は以下の式（５）のように表現できる。

損失関数の和

は近接分離法によって効率的に最小化することができる。ここでは，高速反復収縮しきい値アルゴリズム（ＦＩＳＴＡ）（Ａ． Ｂｅｃｋ， Ｍ． Ｔｅｂｏｕｌｌｅ， ＳＩＡＭ Ｊ． Ｉｍａｇｉｎｇ Ｓｃｉ．， ２， １８３ （２００９））によって高速化した，離散性を考慮したＲＡＦ（ＤＲＡＦ）アルゴリズムを表１に要約する。

Is a set of modulated signals, a loss function that takes discreteness into consideration.

Can be expressed as the following equation (5).

Sum of loss functions

Can be efficiently minimized by the proximity separation method. Here, discreteness-aware RAF (DRAF) accelerated by the Fast Iterative Shrinkage Threshold Algorithm (FISTA) (A. Beck, M. Tebole, SIAM J. Imaging Sci., 2, 183 (2009)). The algorithms are summarized in Table 1.

Here, a proximity map of g (x) is given, for example, as follows (R. Hayagawa and K. Hayashi, IEEE Access, 6, 66499 (2018)).

重みｗ_ｎには種々の選択肢が考えられるが，以下では，簡単のため，

とする。
ここで，

である。またβ_ｎ及びρ_ｎは，それぞれ重み及びサンプルの取捨選択に関するパラメータである。

Various options can be considered for the weight w _n , but the following is for simplicity.

And.
here,

Is. In addition, β _n and ρ _n are parameters related to weight and sample selection, respectively.

As a proof of concept, phase recovery coherent detection of a 10 Gbaud spatial multiplex QPSK signal was demonstrated (Fig. 3 (a)). In the transmitter, a narrow line width laser with a wavelength of 1550.72 nm and a line width of 0.1 kHz was modulated by an optical IQ modulator in a general QPSK format. Polarization with an IQ modulator driven by a 10 GSa / s arbitrary waveform generator (AWG) for single-channel transmission and a 10 GSa / s pulse pattern generator (PPG) for 2-channel spatial multiplexing transmission. A multiplex IQ modulator (was used .. The carrier components in the modulated signal were properly suppressed and no reference light was used as used for heterodyne or Kramers-Kronig detection, etc. The quality of the modulated signal was error. The vector amplitude was <12%. The QPSK signal was amplified to 19 dBm via an erbium-doped fiber amplifier (EDFA). This is high because the prototype 2-D PDA module does not incorporate an amplifier. Optical power was required. The output of the EDFA was input to the 1.6 km GI50 OM3 MMF. Since the transmission system consists of a single mode device, an SC connector was used to connect to the MMF. Therefore, unlike a general SDM transmission that uses orthogonal fiber modes, the fiber modes are excited almost randomly and interfere with each other along the fiber. In this experiment, this interference is positive for phase recovery. That is, the transmission line itself was used as a scramble. Therefore, the receiver is composed only of a two-dimensional PD array and a lens. The PD array consists of 32 elements and has an average bandwidth of 11 GHz. The size was 30 μm × 30 μm, and the pitch was 44 μm (T. Umezawa et al., JLT, 36 (7), 3864 (2018).).

In this experiment, only 12 PDs out of 32 were used due to equipment restrictions. .. In order to effectively increase the number of observations, a 20GSa / s 12-channel digital storage oscilloscope (DSO) is used, the PD output is oversampled at twice the transmission rate, and a fractional interval sample is used to virtually set the number of measurements to 2. It was doubled, that is, _Nr = 12 × 2 = 24. Signal processing was performed offline. In DRAF, M = 64, D = 12 (in symbol rate), μ _n = 6, β _n = 5, ρ _n = 0.4. The weighted maximum correlation initialization method was used for initialization (G. Wang et al., IEEE Trans. Signal Process., 66 (11), 2818 (2018)).

FIG. 4 shows an example of the channel impulse response estimated by RAF in the case of a single channel. As shown in FIG. 4, mode coupling and dispersion in MMFs cause random interference between modes. In the conventional coherent reception system, a complicated mode diversity configuration is required to eliminate this interference, but in the phase reproduction type coherent receiver, this distortion is utilized to recover the optical phase.

5 and 6 show the bit error rate (BER) characteristic vs. the number of iterations N of DRAF for different N _r , respectively. BER is the average of 200 trials in different fiber states. For a given N _r , the N _r channel is selected from the one with the largest standard deviation, and phase retrieval is performed.

For a single transmit channel (Figure 5), a BER below the FEC (forward error correction) threshold with 7% redundancy, ie BER <3.8 × 10 ^-3, becomes N _t > 16 and N> 300. Achieved against. When using the 20% -FEC (BER threshold 2.0 × ^{10 _-2),} in N r> 10 (5 PD) , and N> 400, it was possible to error-free transmission. On the other hand, when the conventional RAF, that is, the phase retrieval method that does not consider the discreteness, was used, error-free transmission could not be achieved even if all 12 PDs ( _Nr = 24) were used. This indicates that the phase retrieval problem following convolutional observations is difficult. The BER characteristics shown in this embodiment are those after the phase noise (PN) removal process based on the fourth power method is applied. In a phase-recovered coherent receiver, the frequency drift of the transmitting side local light is estimated and compensated as part of the channel response _hij . On the other hand, the remaining phase noise component is reconstructed by phase reproduction as shown in the inset of FIG. 5, and can be removed by post-processing like a conventional coherent receiver. This suggests that it is possible to realize a phase-retrieving coherent receiver without using a laser with an extremely narrow line width as in this experiment. Finally, in the case of 2-channel spatial multiplexing transmission (FIG. 6), it can be seen that the BER characteristics are deteriorated due to the correlation between the channels. The mode coupling in the MMF is weak and not sufficiently random interference. Oversampling itself also causes channel correlation. However, 20% -FEC error-free operation could be achieved by using 24 channels (ie 12PD) with N> 400.

The system of the present invention can be used as a low-cost coherent receiver in, for example, short-range ultra-large-capacity optical space multiplex transmission in a data center or an access system, or in optical wireless communication or optical sensing. Therefore, the present invention can be used, for example, in the information and communication industry.

1 System 3 Interference element 5 Detector 7 Detector array 9 Processing circuit

Claims (6)

A system (1) for receiving an optical signal and detecting information including an optical phase.
The interference element (3) for scattering the optical signal and causing interference, and
A detector array (7) including a plurality of detectors (5) for measuring the light intensity of the optical signal in which interference is caused by the interference element (3).
A system including a processing circuit (9) for recovering the phase information of the optical signal by using the information on the light intensity measured by the detector array (7). The system according to claim 1.
The interference element (3) is a system that causes random interference in the optical signal. The system according to claim 1.
Assuming that the number of the plurality of detectors (5) is Nr and the number of channels of the optical signal is Nt, Nr is four times or more of Nt. The system according to claim 1.
The processing circuit (9) is a system that recovers the phase information of the optical signal by using the element related to the discreteness of the optical signal. The system according to claim 1.
The processing circuit (9) estimates an element related to the randomness of the interference element (3) using a known signal, and uses the estimated element related to the randomness of the interference element (3) to obtain the optical signal. A system that recovers phase information. A method for receiving an optical signal and detecting information including the optical phase.
A step in which the interference element (3) scatters the optical phase modulation signal and causes interference.
A step in which the detector array (7) including the plurality of detectors (5) measures the light intensity of the optical signal in which interference is caused by the interference element (3).
A method in which the processing circuit (9) includes a step of recovering the phase information of the optical signal by using the information regarding the light intensity measured by the detector array (7).

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