Optical amplifier, receiver, optical transmission system, and optical amplifier design method

Patent metadata

Field	Value
Publication number	US-2022416897-A1
Application number	US-201917620795-A
Country	US
Kind code	A1
Filing date	Jun 21, 2019
Priority date	Jun 21, 2019
Publication date	Dec 29, 2022
Grant date	—

Abstract

An optical amplifier (21) configured to operate with saturated output power is coupled on the receive side with respect to a receiver (18) coupled to a transmitter (17) via an optical fiber (14). The saturated output power is represented as a saturation characteristic drawing a flat curve in which, as power (input optical power) of an optical signal (22i) inputted to the optical amplifier (21) increases in excess of a given level, the variation in power (output optical power) of an optical signal (22o) outputted from the optical amplifier (21) decreases. Consequently, information represented by the optical signal (22o) inputted from the optical amplifier (21) to the receiver (18) can be properly received.

First claim

1 . An optical amplifier coupled on a receive side with respect to a receiver for receiving an optical signal from a transmitter for optical signal through an optical transmission line, wherein
the optical amplifier is configured to operate with saturated output power.

2 . The optical amplifier according to claim 1 , wherein
an input-power-adjusting optical amplifier is coupled on an input side with respect to the optical amplifier, the input-power-adjusting optical amplifier being configured to increase input optical power to the optical amplifier.

3 . The optical amplifier according to claim 1 , wherein
a pump current of the optical amplifier is decreased in amount.

4 . The optical amplifier according to claim 2 , wherein
when one of the optical amplifier and the input-power-adjusting optical amplifier is implemented as an erbium doped optical fiber amplifier (EDFA), another of the optical amplifier and the input-power-adjusting optical amplifier is implemented as a semiconductor optical amplifier (SOA), or when the one of the optical amplifier and the input-power-adjusting optical amplifier is implemented as an SOA, the other of the optical amplifier and the input-power-adjusting optical amplifier is implemented as an EDFA.

5 . A receiver comprising:
an optical/electrical (O/E) conversion device configured to receive an optical signal transmitted by a transmitter for optical signal through an optical transmission line and convert the optical signal into an analog electrical signal by demodulating the optical signal; an analog/digital (A/D) conversion device configured to convert the electrical signal into a digital signal; a digital signal processing device, including one or more processors, configured to perform digital signal processing including polarization split of the digital signal, compensation for polarization/wavelength dispersion of the digital signal, compensation for waveform distortion of the digital signal, and compensation for frequency/phase offset of the digital signal; and an information recognition device, including one or more processors, configured to recognize information of “0” or “1” from the signal subjected to the digital signal processing, wherein the A/D conversion device includes a sampling device, including one or more processors, configured to perform sampling by sectioning the electrical signal converted by the O/E conversion device at fixed time intervals and read values from the sectioned electrical signal, and a normalization device, including one or more processors, configured to normalize values of M pieces of an electrical signal corresponding to received optical power received through the optical transmission line by dividing each value by an average value of samples obtained in the sampling by sectioning an electrical signal corresponding to received optical power in accordance with a cycle period of a length of N, and when a bit error rate (BER) calculated by using the information of “0” or “1” obtained by the information recognition device in accordance with normalization does not indicate a smallest value, change both N and M to values that minimize the BER or either N or M to a value that minimizes the BER.

6 . An optical transmission system comprising:
the optical amplifier according to claim 1 coupled on a receive side with respect to a receiver for optical signal coupled to a transmitter for optical signal via an optical transmission line.

7 . An optical transmission system comprising: the receiver according to claim 5 coupled to the transmitter for optical signal via the optical transmission line; and
an optical amplifier coupled on a receive side with respect to the receiver and configured to operate with saturated output power.

8 . An optical amplifier design method implemented by an optical amplifier design device for designing an optical amplifier configured to be coupled on a receive side with respect to a receiver for receiving an optical signal from a transmitter for optical signal through an optical transmission line, the optical amplifier being configured to operate with saturated output power, wherein
the optical amplifier design device performs a step of measuring input optical power of an optical signal inputted to the optical amplifier, a step of configuring in a configuration unit an estimated reduction amount of the input optical power due to an instantaneous loss variation caused by a change in bend loss of an optical fiber constituting the optical transmission line, a step of calculating a variation amount of output optical power, the variation amount corresponding to the configured estimated reduction amount, a step of converting the calculated variation amount of output optical power into a BER according to a receive optical signal received by the receiver, and a step of, when the converted BER exceeds a predetermined BER expectation value, changing parameters, notably a parameter regarding material of the optical amplifier and a parameter regarding size of the optical amplifier.

9 . An optical transmission system comprising:
the optical amplifier according to claim 3 coupled on a receive side with respect to a receiver for optical signal coupled to a transmitter for optical signal via an optical transmission line.

10 . An optical transmission system comprising:
the optical amplifier and the input-power-adjusting optical amplifier according to claim 2 coupled on the receive side with respect to the receiver for optical signal coupled to the transmitter for optical signal via the optical transmission line.

11 . An optical transmission system comprising:
the optical amplifier and the input-power-adjusting optical amplifier according to claim 4 coupled on the receive side with respect to the receiver for optical signal coupled to the transmitter for optical signal via the optical transmission line.

Assignees

• Nippon Telegraph & Telephone

Inventors

• Saito Kohei
• Kawahara Hiroki
• Seki Takeshi
• Maeda Hideki

Classifications

• H04B10/293 Primary

  Signal power control · CPC title

• H01S5/50

  Amplifier structures not provided for in groups H01S5/02 - H01S5/30 · CPC title

• H04B10/2914 Primary

  using lumped semiconductor optical amplifiers [SOA] · CPC title