Optical transmission device and optical communication system

Patent metadata

Field	Value
Publication number	US-11942993-B2
Application number	US-202017784104-A
Country	US
Kind code	B2
Filing date	Dec 18, 2020
Priority date	Dec 20, 2019
Publication date	Mar 26, 2024
Grant date	Mar 26, 2024

Abstract

An optical transmission device includes: a control module generate a control signal output which includes a slope adjust signal and a bias voltage offset adjust signal according to an input signal indicating a dispersion amount an electrical level adjust signal; a multi-level pulse amplitude modulator; and an asymmetrical optical modulator which is controlled by the slope adjust signal to be operated at one of a positive slope and a negative slope of a transfer function of the asymmetrical optical modulator itself, and is controlled by the bias voltage offset adjust signal of the control signal output to offset a bias voltage point of the asymmetrical optical modulator itself from a quadrature point of the transfer function, and modulates the multi-level pulse amplitude modulation signal to an optical signal to generate an optical modulate signal having a chirp.

First claim

What is claimed is:

1. An optical transmission device, comprising:
a control module which is used to receive an input signal indicating a dispersion amount, and generate a control signal output comprising a slope adjust signal and a bias voltage offset adjust signal according to the input signal and an electrical level adjust signal changing as the bias voltage offset adjust signal changing, the slope adjust signal and the bias voltage offset adjust signal respectively changing as a polarity and a magnitude of the dispersion amount changing;
a multi-level pulse amplitude modulator which is used to receive a data input, and connects the control module to receive the electrical level adjust signal, and modulates the data input at least according to the electrical level adjust signal, to generate a multi-level pulse amplitude modulation signal; and
an asymmetrical optical modulator which is used to receive an optical signal, and connects the multi-level pulse amplitude modulator and the control module to respectively receive the multi-level pulse amplitude modulation signal and the control signal output, the asymmetrical optical modulator being controlled by the slope adjust signal of the control signal output to be operated at one of a positive slope and a negative slope of a transfer function of the asymmetrical optical modulator itself, and being controlled by the bias voltage offset adjust signal of the control signal output to offset a bias voltage point of the asymmetrical optical modulator itself from a quadrature point of the transfer function, and modulating the multi-level pulse amplitude modulation signal to the optical signal to generate an optical modulate signal having a chirp, a polarity and a magnitude of the chirp respectively changing as the slope adjust signal and the bias voltage offset adjust signal changing.

2. The optical transmission device of claim 1 , wherein
the control module generates a polarity adjust signal further according to the slope adjust signal, the polarity adjust signal changes as the slope adjust signal change; and
the multi-level pulse amplitude modulator further receives the polarity adjust signal from the control module, and further modulates the data input according to the polarity adjust signal, to generate the multi-level pulse amplitude modulation signal.

3. The optical transmission device of claim 2 , wherein the control module comprises:
a slope controller which connects the multi-level pulse amplitude modulator, and generates the slope adjust signal according to the polarity of the input signal of the dispersion amount, and generates and outputs the polarity adjust signal to the multi-level pulse amplitude modulator according to the slope adjust signal;
a bias voltage offset controller which generates the bias voltage offset adjust signal according to the magnitude of the dispersion amount of the input signal;
an optical modulator bias voltage controller which connects the asymmetrical optical modulator, the slope controller and the bias voltage offset controller, receives the slope adjust signal and the bias voltage offset adjust signal respectively from the slope controller and the bias voltage offset controller, and generates and outputs the control signal output to the asymmetrical optical modulator according to the slope adjust signal and the bias voltage offset adjust signal; and
an electrical level adjustor which connects the multi-level pulse amplitude modulator and the bias voltage offset controller, and generates and outputs the electrical level adjust signal to the multi-level pulse amplitude modulator according to the bias voltage offset adjust signal.

4. The optical transmission device of claim 2 , wherein
when the asymmetrical optical modulator is controlled by the slope adjust signal to be operated at the negative slope of the transfer function of the asymmetrical optical modulator itself, the control module generates and outputs the polarity adjust signal to the multi-level pulse amplitude modulator, to cause the polarity of the multi-level pulse amplitude modulation signal generated by the multi-level pulse amplitude modulator to be reversed.

5. The optical transmission device of claim 1 , wherein
when the polarity of the dispersion amount is positive polarity, the chirp had by the asymmetrical optical modulator is negative polarity,
when the polarity of the dispersion amount is negative polarity, the chirp of the asymmetrical optical modulator is positive polarity.

6. The optical transmission device of claim 1 , wherein
the multi-level pulse amplitude modulation signal is a four-level pulse amplitude modulation signal, and the four-level pulse amplitude modulation signal has a zeroth electrical level, a first electrical level, a second electrical level and a third electrical level;
when the asymmetrical optical modulator is operated at the positive slope of the transfer function and is controlled by the bias voltage offset adjust signal so that the bias voltage point of the asymmetrical optical modulator itself offsets to above the quadrature point of the positive slope of the transfer function, the multi-level pulse amplitude modulator modulates the data input according to the electrical level adjust signal, to cause the first electrical level and the second electrical level of the multi-level pulse amplitude modulation signal generated by the multi-level pulse amplitude modulator to offset toward the zeroth electrical level; and
when the asymmetrical optical modulator is operated at the positive slope of the transfer function and is controlled by the bias voltage offset adjust signal so that the bias voltage point of the asymmetrical optical modulator itself offsets to below the quadrature point of the positive slope of the transfer function, the multi-level pulse amplitude modulator modulates the data input according to the electrical level adjust signal, to cause the first electrical level and the second electrical level of the multi-level pulse amplitude modulation signal generated by the multi-level pulse amplitude modulator to offset toward the third electrical level.

7. The optical transmission device of claim 6 , wherein
when the asymmetrical optical modulator is operated at the negative slope of the transfer function and is controlled by the bias voltage offset adjust signal so that the bias voltage point of the asymmetrical optical modulator itself offsets to above the quadrature point of the negative slope of the transfer function, the multi-level pulse amplitude modulator modulates the data input according to the electrical level adjust signal, to cause the first electrical level and the second electrical level of the multi-level pulse amplitude modulation signal generate by the multi-level pulse amplitude modulator to offset toward the third electrical level; and
when the asymmetrical optical modulator is operated at the negative slope of the transfer function and is controlled by the bias voltage offset adjust signal so that the bias voltage point of the asymmetrical optical modulator itself offsets to below the quadrature point of the negative slope of the transfer function, the multi-level pulse amplitude modulator modulates the data input according to the electrical level adjust signal, to cause the first electrical level and the second electrical level of the multi-level pulse amplitude modulation signal generated by the multi-level pulse amplitude modulator to offset toward the zeroth electrical level.

8. The optical transmission device of claim 1 , further comprising an amplifier which is connected between the multi-level pulse amplitude modulator and the asymmetrical optical modulator, amplifies the multi-level pulse amplitude modulation signal from the multi-leve

Assignees

• Molex Llc

Inventors

• Tsai Kuen-Ting
• Chen Wei-Hung
• Chuang Zuon-Min
• Liang yao-wen

Classifications

• H04B10/25137 Primary

  using pulse shaping at the transmitter, e.g. pre-chirping or dispersion supported transmission [DST] · CPC title

• G02F1/212

  Mach-Zehnder type · CPC title

• H04B1/69

  Spread spectrum techniques · CPC title

• H04B10/524

  Pulse modulation · CPC title

• H04B10/541

  Digital intensity or amplitude modulation · CPC title