JP5750920B2 - Optical receiver module - Google Patents

Description

  The present invention relates to an optical receiver module.

  Non-Patent Document 1 below describes the standard of an optical transceiver for 100 GB Ethernet (registered trademark). This optical transceiver transmits a 100 GB optical signal by wavelength-multiplexing four 25 Gbps optical signals having different wavelengths. Therefore, the optical transceiver includes four optical transmission subassemblies (TOSA) and four optical reception subassemblies (ROSA).

  When long distance transmission such as 40 km is performed by such an optical transceiver, transmission loss of an optical signal may occur. Therefore, in order to amplify the light input to the ROSA, the optical transceiver may be mounted with a semiconductor optical amplifier.

  In an optical transceiver equipped with a semiconductor optical amplifier, generally, the bias current and temperature of the semiconductor optical amplifier are adjusted by monitoring the output of the ROSA to control the amplification factor (gain) of the semiconductor optical amplifier. Has been done. Such a technique is described, for example, in Patent Document 1 below.

JP 2010-98166 A

Chris Cole et al., "100GBE-OPTICAL LAN TECHNOLOGIES", IEEE Applications & Practice, December 2007, pp. 12-19

  By the way, in the optical transceiver described above, not the power of the optical signal after being amplified by the semiconductor optical amplifier, but the power of the optical signal before being input to the semiconductor optical amplifier, that is, the optical signal including the semiconductor optical amplifier. There is a demand for monitoring the power of optical signals.

  One countermeasure against this requirement is to branch the input optical signal to the semiconductor optical amplifier with an optical branching device, give a part of the branched optical signal to the semiconductor optical amplifier, and monitor the other part with the optical receiver. It is. However, this measure has the following problems. That is, since the optical signal is branched by the optical branching element, the power of the optical signal input to the semiconductor optical amplifier is reduced. When the power of the optical signal input to the semiconductor optical amplifier is reduced, OSNR (Optical Sine Noise Ratio) is degraded, and as a result, the signal quality generated by the photoelectric conversion is also degraded. This signal quality degradation can cause an error floor.

  Therefore, there is a need in the art for an optical receiver module that can monitor the power of an optical signal input to a semiconductor optical amplifier without using an optical branching element.

  An optical receiver module according to one aspect of the present invention includes a semiconductor optical amplifier, an optical receiver, a first arithmetic device, a driving device, a storage unit, and a second arithmetic device. The semiconductor optical amplifier amplifies an input optical signal. The optical receiver is optically coupled to the semiconductor optical amplifier. The optical receiver generates an electrical signal corresponding to the magnitude of the amplified optical signal. The first arithmetic unit calculates a bias current value applied to the semiconductor optical amplifier and a temperature of the semiconductor optical amplifier (hereinafter referred to as SOA temperature) based on an electrical signal generated by the optical receiver. The driving device drives the semiconductor optical amplifier. The drive device sets the bias current value and temperature calculated by the first arithmetic device for the semiconductor optical amplifier. The storage means stores gain and noise figure data of the semiconductor optical amplifier corresponding to the bias current value and temperature. The second arithmetic unit is a semiconductor optical amplifier based on the data acquired from the storage means and corresponding to the bias current value and temperature set by the driving device and the electrical signal of the optical receiver. The power of the optical signal input to is calculated.

  This optical receiver module is based on the bias current value set for the semiconductor optical amplifier, the gain of the semiconductor optical amplifier corresponding to the SOA temperature, the noise figure data, and the electrical signal of the optical receiver. The power of the input optical signal is calculated. Therefore, the power of the optical signal input to the semiconductor optical amplifier can be monitored without using the optical branching element.

  In one embodiment, the input optical signal to the semiconductor optical amplifier may include a plurality of optical signals having different wavelengths. In this form, the optical receiver module may include a plurality of optical receivers including the optical receiver and an optical demultiplexer. The optical demultiplexer is optically coupled to the semiconductor optical amplifier and the plurality of optical receivers. The optical demultiplexer couples a plurality of optical signals from the semiconductor optical amplifier to a plurality of optical receivers, respectively. The storage means can store gain and noise figure data of the semiconductor optical amplifier corresponding to the bias current value and the SOA temperature for each wavelength of the plurality of optical signals. The second arithmetic device is data acquired from the storage means for each wavelength of the plurality of optical signals, the data for the wavelength corresponding to the bias current value and the SOA temperature set by the driving device, and the wavelength The power of the input optical signal to the semiconductor optical amplifier can be calculated based on the electrical signal from the optical receiver corresponding to. According to the optical receiver module of this aspect, the power of the input optical signal to the semiconductor optical amplifier can be monitored for each wavelength without using the optical branching element.

As described above, according to the present invention, an optical receiver module capable of monitoring the power of the input optical signal to be a Ku semiconductor optical amplifier using an optical branching device is provided.

It is a figure which shows the optical transceiver which concerns on one Embodiment. It is a figure which shows the optical receiver module which concerns on one Embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals.

  FIG. 1 is a diagram illustrating an optical transceiver according to an embodiment. The optical receiver module of one embodiment of the present invention can be realized as an element of the optical transceiver 10 shown in FIG. The optical transceiver 10 according to an embodiment performs wavelength division multiplexing communication of optical signals having four different wavelengths. For example, optical communication of 100 Gbps can be realized using four optical signals of 25 Gbps.

  As shown in FIG. 1, the optical transceiver 10 includes an optical transmission module 12 and an optical reception module 14. The optical transmission module 12 may include an optical multiplexer 16, light emitting elements 18 a, 18 b, 18 c, 18 d, drive circuits 20 a, 20 b, 20 c, 20 d, and a signal conversion processing unit 22.

  The optical multiplexer 16 is an optical multiplexer that multiplexes four optical signals having different wavelengths generated by the light emitting elements 18a, 18b, 18c, and 18d. The optical multiplexer 16 couples the multiplexed optical signal to the optical fiber F1.

  The light emitting elements 18a, 18b, 18c, and 18d are, for example, electroabsorption lasers, and generate optical signals having different wavelengths in response to driving currents or driving voltages from the driving circuits 20a, 20b, 20c, and 20d, respectively.

  The drive circuits 20a, 20b, 20c, and 20d receive an electrical signal from the signal conversion processing unit 22 and output a drive current or a drive voltage. The signal conversion processing unit 22 converts the 100 Gbps signal received from the host host into four 25 Gbps electrical signals, and outputs the four electrical signals to the drive circuits 20a, 20b, 20c, and 20d, respectively.

  FIG. 2 is a diagram illustrating an optical receiver module according to an embodiment. As shown in FIGS. 1 and 2, the optical receiver module 14 generates an electrical signal based on the optical signal received from the external optical fiber F2.

  As shown in FIG. 2, the optical receiver module 14 includes a semiconductor optical amplifier 30, an optical demultiplexer 32, optical receivers 34 a, 34 b, 34 c, 34 d, a signal conversion processing unit 36, a first arithmetic device 40, and a driving device 42. , A memory 44, and a second arithmetic unit 46.

  The semiconductor optical amplifier 30 is optically coupled to the optical fiber F2. The semiconductor optical amplifier 30 amplifies the optical signal received from the optical fiber F2 and outputs the amplified optical signal. The amplification factor of the semiconductor optical amplifier 30 is adjusted by the bias current applied to the semiconductor optical amplifier and the SOA temperature. In the present embodiment, the signal light from the optical fiber F2 includes four optical signals having different wavelengths. The output of the semiconductor optical amplifier 30 is optically coupled to the optical demultiplexer 32.

  The optical demultiplexer 32 is an optical demultiplexer that wavelength-divides the amplified optical signal received from the semiconductor optical amplifier 30 into four optical signals. Four optical signals from the optical demultiplexer 32 are input to optical receivers 34a, 34b, 34c, and 34d, respectively.

  Each of the optical receivers 34a, 34b, 34c, and 34d performs photoelectric conversion on the input optical signal, and outputs an electrical signal having a value corresponding to the power of the optical signal. The optical receiver 34a includes a photodiode 50a and a transimpedance amplifier 52a, the optical receiver 34b includes a photodiode 50b and a transimpedance amplifier 52b, and the optical receiver 34c includes the photodiode 50c and the transimpedance amplifier 52c. The optical receiver 34d can include a photodiode 50d and a transimpedance amplifier 52d. Each of the photodiodes 50a, 50b, 50c, and 50d generates a photocurrent corresponding to the power of the input optical signal. The transimpedance amplifiers 52a, 52b, 52c, and 52d convert input photocurrents into electrical signals (voltages).

  The electrical signals from the optical receivers 34a, 34b, 34c, and 34d can each be 25 Gbps electrical signals. The signal conversion processing unit 36 receives the electrical signals from the optical receivers 34a, 34b, 34c, and 34d and generates a 100 Gbps electrical signal. The signal conversion processing unit 36 outputs the generated electrical signal to an external host.

  The first arithmetic device 40 calculates the bias current that the driving device 42 should give to the semiconductor optical amplifier 30 and the temperature of the semiconductor optical amplifier 30. The first arithmetic device 40 may be configured by an arbitrary arithmetic circuit such as a CPU, for example.

  The first arithmetic unit 40 does not change the bias current value when the output electric signals of the optical receivers 34a, 34b, 34c, 34d all have a value between a predetermined upper limit value and a lower limit value. The current value is fixed. The first arithmetic unit 40 biases to lower the amplification factor of the semiconductor optical amplifier 30 when any of the output electrical signals of the optical receivers 34a, 34b, 34c, 34d has a value exceeding a predetermined upper limit value. The current value is decreased by a predetermined amount, or the temperature of the semiconductor optical amplifier 30 is increased by a predetermined amount. Further, the first arithmetic unit 40 increases the bias current value by a predetermined amount when any of the output electrical signals of the optical receivers 34a, 34b, 34c, 34d has a value smaller than a predetermined lower limit value. Alternatively, the temperature of the semiconductor optical amplifier 30 is lowered by a predetermined amount. Further, when the bias current exceeds the maximum upper limit value or falls below the minimum lower limit value, or the temperature of the semiconductor optical amplifier 30 exceeds the maximum upper limit value or falls below the minimum lower limit value, the first arithmetic unit 40 determines the bias current value. Is maintained at a predetermined minimum value, and the temperature of the semiconductor optical amplifier 30 is set to a predetermined temperature. Through such control, the first arithmetic unit 40 calculates the bias current and temperature to be given to the semiconductor optical amplifier 30.

  The driving device 42 supplies the semiconductor optical amplifier 30 with a bias current having a value set by the first arithmetic device 40. In addition, the driving device 42 sets the temperature of the semiconductor optical amplifier 30 to the temperature of the value set by the first arithmetic device 40. For example, the driving device 42 sets the temperature of the semiconductor optical amplifier 30 using a Peltier element attached to the semiconductor optical amplifier 30.

  The memory 44 stores the gain (gain G) and noise figure (NF) data of the semiconductor optical amplifier 30 corresponding to the bias current value and temperature of the semiconductor optical amplifier 30 for each wavelength. That is, when the wavelength is λ and the bias current and temperature of the semiconductor optical amplifier 30 are I and T, respectively, the gain G and the noise figure NF are the wavelength λ of the optical signal, the bias current I of the semiconductor amplifier 30, and the semiconductor amplifier 30. The memory 44 stores G (λ, I, T) and NF (λ, I, T) data. The memory 44 may store G (λ, I, T) and NF (λ, I, T) in the form of a table or may store them in the form of a function.

  The second arithmetic unit 46 obtains the bias current value and the SOA temperature given to the semiconductor optical amplifier 30 via the drive unit 42, and gains G (λ, I, etc.) corresponding to the bias current value and the SOA temperature. T) and noise figure NF (λ, I, T) are acquired from the memory 44 for each wavelength. The second arithmetic unit 46 uses the acquired gain G (λ, I, T) and noise figure NF (λ, I, T) and the output electrical signals of the optical receivers 34a, 34b, 34c, 34d, The power of the input optical signal to the semiconductor optical amplifier 30 is calculated for each wavelength. The power of the input optical signal calculated by the second arithmetic unit 46 can be provided to an external host. The second arithmetic unit 46 may be configured by an arbitrary arithmetic circuit such as a CPU, for example.

なお、Ｐｏｕｔ、Ｐｉｎの単位はｍＷであり、ＮＦは無単位である。光トランシーバへの全光入力パワーＰｔｏｔａｌ求める場合には、下記（２）式が用いられてもよい。

Here, the gain G (λ, I, T), the noise figure NF (λ, I, T), the power Pout (λ) of the output electric signal of the optical receivers 34a, 34b, 34c, 34d, and the optical signal The power Pin (λ) has a relationship specified by the following formula (1).

The unit of Pout and Pin is mW, and NF is no unit. When obtaining the all-optical input power Ptotal to the optical transceiver, the following equation (2) may be used.

  The second arithmetic unit 46 uses the gain G (λ, I, T), the noise figure NF (λ, I, T), and the power Pout (λ) of the output electric signal from the optical receivers 34a, 34b, 34c, 34d. The power Pin (λ) of the optical signal is calculated for each wavelength according to the above formula (1).

  As described above, the optical receiving module 14 can obtain the power of the optical signal input to the semiconductor optical amplifier 30 without using the optical branching element. Further, the power of the input optical signal to the semiconductor optical amplifier 30 can be obtained for each wavelength without using a separate optical demultiplexer for monitoring.

  Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and various modifications can be made. For example, the idea of the present invention can be applied to an optical receiver module that performs communication using one or more optical signals having one or more wavelengths, and an optical transceiver equipped with the optical module.

  DESCRIPTION OF SYMBOLS 10 ... Optical transceiver, 12 ... Optical transmission module, 14 ... Optical receiving module, 30 ... Semiconductor optical amplifier, 32 ... Optical demultiplexer, 34a, 34b, 34c, 34d ... Optical receiver, 36 ... Signal conversion process part, 40 ... First arithmetic device 42... Drive device 44. Memory 46. Second arithmetic device 50a, 50b, 50c, 50d Photodiode 52a 52b 52c 52d Transimpedance amplifier.

Claims (3)

A semiconductor optical amplifier for amplifying an input optical signal;
An optical receiver optically coupled to the semiconductor optical amplifier, wherein the optical receiver generates an electrical signal corresponding to the magnitude of an amplified optical signal from the semiconductor optical amplifier;
A first arithmetic unit for setting a bias current value applied to the semiconductor optical amplifier and a temperature of the semiconductor optical amplifier;
A driving device for driving the semiconductor optical amplifier, wherein the driving device sets the bias current value and the temperature set by the first arithmetic device for the semiconductor optical amplifier;
Storage means for storing gain and noise figure data of the semiconductor optical amplifier corresponding to the bias current value and the temperature;
A data gain and noise figure of the semiconductor optical amplifier is obtained from the bias current value and the storage means are attached corresponding to the temperature set for the semiconductor optical amplifier by the driving device, the bias current And a power of an optical signal input to the semiconductor optical amplifier based on an electrical signal generated by the optical receiver in response to an amplified optical signal from the semiconductor optical amplifier, the temperature of which is set . An arithmetic unit of
An optical receiver module comprising: The input optical signal to the semiconductor optical amplifier includes a plurality of optical signals having different wavelengths,
A plurality of optical receivers including the optical receiver;
An optical demultiplexer optically coupled to the semiconductor optical amplifier and the plurality of optical receivers, wherein the optical demultiplexers respectively couple the plurality of optical signals from the semiconductor optical amplifier to the plurality of optical receivers. Waver,
Further comprising
The storage means stores the gain and noise figure data of the semiconductor optical amplifier corresponding to the bias current value and the temperature of the semiconductor optical amplifier for each wavelength of the plurality of optical signals,
The second arithmetic unit, for each wavelength of said plurality of optical signals, obtained from the bias current value and the storage means are attached corresponding to the temperature set for the semiconductor optical amplifier by the drive device The optical reception in response to the data for the wavelength to be transmitted and an electric signal from the optical receiver corresponding to the wavelength and the amplified optical signal from the semiconductor optical amplifier in which the bias current and the temperature are set Calculating the power of the input optical signal to the semiconductor optical amplifier based on the electrical signal generated by the device ;
The optical receiver module according to claim 1. The first arithmetic unit determines a bias current value to be given to the semiconductor optical amplifier when the electrical signal generated by the optical receiver has a value between a predetermined upper limit value and a predetermined lower limit value. When the electric signal generated by the optical receiver has a value larger than the predetermined upper limit value, the bias current value applied to the semiconductor optical amplifier is reduced by a predetermined amount. Or set the temperature of the semiconductor optical amplifier to a temperature increased by a predetermined amount, and when the electrical signal generated by the optical receiver has a value smaller than the predetermined lower limit, A bias current value applied to the semiconductor optical amplifier is set to a value increased by a predetermined amount, or the temperature of the semiconductor optical amplifier is set to a temperature decreased by a predetermined amount,
The optical receiver module according to claim 1 or 2.

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