Polarization Insensitive Micro Ring Modulator

Patent metadata

Field	Value
Publication number	US-2018335652-A1
Application number	US-201715601706-A
Country	US
Kind code	A1
Filing date	May 22, 2017
Priority date	May 22, 2017
Publication date	Nov 22, 2018
Grant date	—

Abstract

A transmission-type polarization insensitive modulator implemented as a polarization insensitive micro ring modulator (PIMRM) includes a first polarization splitter-rotator (PSR) configured to generate a first light beam and a second light beam having a common polarization from an input, a micro ring configured to modulate the first light beam with data to generate a first output signal, and modulate the second light beam with data to generate a second output signal, and a second PSR configured to combine the first output signal and the second output signal to form a modulated output signal, wherein the micro ring is disposed in between the first PSR and the second PSR.

First claim

1 . An apparatus comprising a transmission-type polarization insensitive modulator, the apparatus comprises:
an input configured to receive a continuous wave (CW) light; a first polarization splitter-rotator (PSR) coupled to the input and configured to generate a first light beam and a second light beam having a common polarization from the CW light; an upper waveguide bus coupled to the first PSR and comprising a first tap; a lower waveguide bus coupled to the first PSR and comprising a second tap; a micro ring optically coupled to the upper waveguide bus and the lower waveguide bus, and configured to:
modulate the first light beam with data to generate a first drop signal and a first pass signal, both the first drop signal and the first pass signal having a same wavelength, the first drop signal being transmitted around the micro ring and to the lower waveguide bus, the first pass signal being transmitted along the upper waveguide bus; and
modulate the second light beam with data to generate a second drop signal and a second pass signal, both the second drop signal and the second pass signal having a same wavelength, the second drop signal being transmitted around the micro ring and to the upper waveguide bus, the second pass signal being transmitted along the lower waveguide bus;
the first tap configured to couple out a first portion of the first pass signal to send to a monitor photodetector,
the second tap configured to couple out a second portion of the second pass signal to send to the monitor photodetector, and
the monitor photodetector configured to adjust a temperature of the micro ring,
a second PSR coupled to the upper waveguide bus and the lower waveguide bus and configured to combine the first pass signal and the second pass signal to form a modulated output signal,
the first tap disposed on the upper waveguide bus between the micro ring and the second PSR, and
the second tap disposed on the lower waveguide bus between the micro ring and the second PSR; and
an output coupled to the second PSR and configured to output the modulated output signal to an optical receiving device.

2 . The apparatus of claim 1 , wherein the first PSR is further configured to:
split the CW light into the first light beam having a transverse electric (TE) polarization and a third light beam having a transverse magnetic (TM) polarization; and rotate the third light beam having the TM polarization to generate the second light beam having the TE polarization.

3 .- 4 . (canceled)

5 . The apparatus of claim 1 , wherein the monitor photodetector is configured to generate a combined photodetector current based on the first portion of the first pass signal and the second portion of the second pass signal, wherein the apparatus further comprises:
a heater coupled to the micro ring; and a bias controller coupled to the monitor photodetector and configured to:
generate a bias current based on the combined photodetector current; and
apply the bias current to the heater such that the temperature of the heater is changed according to the bias current, wherein the temperature of micro ring changes according to the temperature of the heater.

6 . The apparatus of claim 5 , wherein the first portion is about 1-5 percent (%) of the first pass signal, and wherein the second portion is about 1-5% of the second pass signal.

7 . A transmission-type modulator, comprising:
a first polarization splitter-rotator (PSR) configured to generate a first light beam and a second light beam having a common polarization from an input; a micro ring resonator configured to:
modulate the first light beam with data to generate a first drop signal and a first pass signal, both the first drop signal and the first pass signal having a same wavelength, the first drop signal being transmitted around the micro ring and to a lower waveguide bus, the first pass signal being transmitted along an upper waveguide bus; and
modulate the second light beam with data to generate a second drop signal and a second pass signal, both the second drop signal and the second pass signal having a same wavelength, the second drop signal being transmitted around the micro ring and to the upper waveguide bus, the second pass signal being transmitted along the lower waveguide bus; and
a second PSR configured to combine the first pass signal and the second pass signal to form a modulated output signal, wherein the micro ring is disposed in between the first PSR and the second PSR, the upper waveguide bus comprising a first tap disposed between the micro ring and the second PSR and configured to couple out a first portion of the first pass signal to send to a monitor photodetector, the lower waveguide bus comprising a second tap disposed between the micro ring and the second PSR and configured to couple out a second portion of the second pass signal to send to the monitor photodetector, the monitor photodetector configured to adjust a temperature of the micro ring.

8 . The transmission-type modulator of claim 7 , further comprising the upper waveguide bus and the lower waveguide bus, wherein a top portion of the micro ring is optically coupled to the upper waveguide bus, and wherein a bottom portion of the micro ring is optically coupled to the lower waveguide bus.

9 . The transmission-type modulator of claim 7 , wherein the first modulated drop signal passes through the micro ring and back to the first PSR, wherein the first drop signal passes through the micro ring and back to the first PSR, and wherein the second drop signal passes through the micro ring and back to the first PSR.

10 . (canceled)

11 . The transmission-type modulator of claim 7 , wherein an amplitude transfer function of the first pass signal and the second pass signal is defined by the equation

H
pass

=

E
pass

E
input

=

t
-

tae

j



φ

1
-

t
2



ae

j



φ

,

wherein E pass is the optical field for the first pass signal or the second pass signal, e is a natural exponential function, ϕ is a single-pass phase shift, k is a predefined cross-coupling coefficient, t is a predefined self-coupling coefficient, a is a single pass amplitude t

Assignees

• Futurewei Technologies Inc

Inventors

• Wen Yangjing
• Bai Yu Sheng
• Wei Hongzhen

Classifications

• G02B6/29335

  Evanescent coupling to a resonator cavity, i.e. between a waveguide mode and a resonant mode of the cavity (wavelength selective means based on resonator cavity coupled non-evanescently G02B6/29356, G02B6/29358) · CPC title

• G02F1/0123

  Circuits for the control or stabilisation of the bias voltage, e.g. automatic bias control [ABC] feedback loops · CPC title

• G02F2203/06

  Polarisation independent · CPC title

• G02F1/011 Primary

  in optical waveguides, not otherwise provided for in this subclass · CPC title

• G02F1/0147

  based on thermo-optic effects (G02F1/132 takes precedence) · CPC title