US 12,451,970 B2 · Dynamic modulator bias controller with continuous waveform characterization via two or more bias points

Abstract

A communication system includes a laser that generates a laser light and a modulator that includes a modulation element configured to modulate the laser light with an input signal based on a bias voltage to produce an output signal. Control circuitry provides the bias voltage to a bias input of the modulation element and is configured to maintain a bias lock on at least two bias points of the modulation element during operation. The control circuitry is programmed to perform a bias lock operation that includes performing an initial voltage sweep on the modulation element and establish initial bias values for the at least two bias points. The circuit also providing a bias waveform to the bias input of the modulation element that varies over time and contains identifiable dither tones, determines harmonic power at the at least two bias points; and varies the bias waveform to determine harmonic power until the harmonic power is minimized to establish a bias lock with locked bias values.

Claims17

Dependent claims

A communication system comprising:

a laser that generates a laser light;
a modulator that includes a modulation element configured to modulate the laser light with an input signal based on a bias voltage to produce an output signal;
control circuitry that provides the bias voltage to a bias input of the modulation element;
and
a signal splitter that receives the output signal and provides the output signal to an output of the system and to the control circuitry;
wherein the control circuitry is configured to maintain a bias lock on at least two bias points of the modulation element during operation and is programmed to perform a bias lock operation that includes:
performing an initial voltage sweep on the modulation element by ramping the bias voltage from a minimum value to a maximum and recording results of the initial sweep based on the output signal;
establishing initial bias values for the at least two bias points by examining the results;
providing a bias waveform to the bias input of the modulation element that varies over time and contains at least two identifiable and different dither tones, one for each of the at least two bias points;
determining harmonic power at the at least two bias points;
and
varying the bias waveform to determine harmonic power until the harmonic power is minimized to establish a bias lock with locked bias values.

9 more elements

A method of operating a communication system that includes a laser that generates a laser light and a modulator that includes a modulation element configured to modulate the laser light with a data signal and a bias signal to produce an output signal, the method comprising:

providing with control circuitry the bias voltage to a bias input of the modulation element;
splitting the output signal and providing the output signal to an output of the system and to the control circuitry;
maintaining a bias lock on at least two bias points of the modulation element during operation with the control circuitry, wherein maintaining includes:
performing an initial voltage sweep on the modulation element by ramping the bias voltage from a minimum value to a maximum and recording results of the initial voltage sweep based on the output signal;
establishing initial bias values for the at least two bias point by examining the results;
providing a bias locking signal to the bias input of the modulation element that varies sequentially over each of the initial bias values over time, wherein the signal includes a dither tone for each of the at least two points that is uniquely identifiable;
determining harmonic power at the initial bias values;
and
varying the biasing signal around the initial bias values;
and
determining harmonic power until the harmonic power is minimized to establish a locked bias signal with locked bias values.

8 more elements

Dependencies are inferred from the claim text.

Dynamic modulator bias controller with continuous waveform characterization via two or more bias points

Life of this patent

Dynamic modulator bias controller with continuous waveform characterization via two or more bias points

Life of this patent

Abstract

Claims17