Distributed travelling-wave mach-zehnder modulator driver

Patent metadata

Field	Value
Publication number	US-10530487-B2
Application number	US-201916398422-A
Country	US
Kind code	B2
Filing date	Apr 30, 2019
Priority date	Feb 10, 2014
Publication date	Jan 7, 2020
Grant date	Jan 7, 2020

Abstract

A distributed traveling-wave Mach-Zehnder modulator driver having a plurality of modulation stages that operate cooperatively (in-phase) to provide a signal suitable for use in a 100 Gb/s optical fiber transmitter at power levels that are compatible with conventional semiconductor devices and conventional semiconductor processing is described.

First claim

What is claimed is:

1. A distributed traveling wave modulator, comprising:
an optical input for receiving an input optical signal and splitting the input optical signal into first and second portions;
a first plurality of optical phase-shifters connected in series optically coupled to the optical input for receiving the first portion of the input optical signal;
a second plurality of optical phase-shifters connected in series optically coupled to the optical input for receiving the second portion of the input optical signal, respective pairs of the first and second plurality of optical phase-shifters forming sequential modulators;
an optical output for recombining the first and second portions forming a modulated output optical signal;
a differential electrical data input connected to a data source;
a plurality of driver amplifier stages, each including a respective differential driver amplifier input, a differential driver amplifier output, and a differential signal output connected to a respective one of the sequential modulators, the differential driver amplifier input of a first of said plurality of driver amplifier stages connected to the differential electrical data input; and
a plurality of delay/relay stages, each including a respective differential delay/relay input connected to a differential driver amplifier output of a previous driver amplifier stage, and a differential delay/relay output connected to a differential driver amplifier input of a following driver amplifier stage;
wherein an optical delay of each optical phase-shifter plus optical waveguide wiring matches a delay between the driver amplifier stages so that modulations constructively add.

2. The modulator according to claim 1 , wherein each output of each driver amplifier stage is configured to be an open-collector driver for driving modulator segments with different impedances.

3. The modulator according to claim 1 , wherein each differential driver amplifier output of each driver amplifier stage is configured to comprise an open-collector cascode driver for driving the sequential modulators with different selectively interchangeable impedances.

4. The modulator amplifier according to claim 3 , wherein each differential driver amplifier output of each driver amplifier stage is configured to be an open-collector driver for driving both 25Ω and 50Ω impedance modulator segments.

5. The modulator according to claim 1 , further comprising:
a plurality of DC bias structures, each DC bias structure configured to individually control one of said plurality of delay/relay stages;
wherein each DC bias structures is capable of controlling an on state and an off state of a respective delay/relay stage for shutting down individual delay/relay stages.

6. The modulator according to claim 5 , wherein further comprising DC bias structures also capable of controlling an on state and an off state of a respective driver amplifier stage for shutting down individual driver amplifier stages.

7. The modulator according to claim 1 , further comprising:
a plurality of DC bias structures, each DC bias structure configured to individually control one of said plurality of driver amplifier stages;
wherein each DC bias structures is capable of controlling an on state and an off state of a respective driver amplifier stage for shutting down individual driver amplifier stages.

8. The modulator according to claim 1 , wherein each driver amplifier stage includes only a single type of transistor to enable high-speed operation.

9. The modulator according to claim 1 , wherein each of the plurality of first and second optical phase shifters comprise a fixed optical length.

10. The modulator according to claim 1 , wherein each of the driver amplifier stages includes a pre-amplifier stage.

11. The modulator according to claim 1 , wherein each pair of optical phase shifters comprises a Mach-Zehnder interferometer modulator.

12. The modulator according to claim 1 , wherein each of the first and second portions have equal intensities.

13. The modulator according to claim 1 , wherein the plurality of driver amplifier stages comprises four, and the number of delay/relay stages comprises three.

14. The modulator according to claim 1 , wherein each driver amplifier stage includes:
a first pair of emitter followers including termination resistors connected to the differential driver amplifier input;
a pre-amplifier comprising a differential pair;
a buffer comprising a second pair of emitter followers; and
a splitter for splitting the input signal into first and second differential output signals for output the differential driver amplifier output, and the differential signal output, respectively.

Assignees

• Elenion Tech Llc

Inventors

• Ding Ran
• Baehr-Jones Thomas Wetteland
• Hochberg Michael J
• Rylyakov Alexander

Classifications

• G02F2201/127

  travelling wave · CPC title

• H04B10/5561 Primary

  Digital phase modulation · CPC title

• H04B10/5161

  Combination of different modulation schemes · CPC title

• G02F1/2257

  the optical waveguides being made of semiconducting material · CPC title

• G02F1/025

  in an optical waveguide structure (G02F1/017, {G02F1/2257} take precedence) · CPC title