# US 9,438,008 B1 · Temperature insensitive external cavity lasers on silicon

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- Number: US 9,438,008 B1
- Document ID: US9438008B1
- Status: Granted
- Kind: B1
- Application number: 14/748,387
- Filed: 2015-06-24
- Granted: 2016-09-06
- Earliest claimed: 2015-04-09
- Assignees: International Business Machines Corporation
- Applicants: International Business Machines Corporation
- Inventors: Jason S. Orcutt
- Web page: https://patentgrep.com/patent/US9438008B1

## CPC

- H01S 3/136: by controlling devices placed within the cavity
- H01S 3/10053: {Phase control}
- H01S 3/106: by controlling devices placed within the cavity ({H01S3/10076,} H01S3/13 take precedence)
- H01S 5/021: {Silicon based substrates}
- H01S 5/02255: using beam deflecting elements
- H01S 5/0287: {Facet reflectivity}
- H01S 5/042: Electrical excitation {; Circuits therefor (monolithically integrated laser drive components H01S5/0261)}
- H01S 5/06821: {Stabilising other output parameters than intensity or frequency, e.g. phase, polarisation or far-fields}
- H01S 5/12: the resonator having a periodic structure, e.g. in distributed feedback [DFB] lasers (comprising a photonic bandgap structure H01S5/11; surface-emitting lasers H01S5/18)
- H01S 5/125: Distributed Bragg reflector [DBR] lasers
- H01S 5/14: External cavity lasers (H01S5/18 takes precedence; mode locking H01S5/065)
- H01S 5/141: {using a wavelength selective device, e.g. a grating or etalon (H01S5/146 takes precedence)}
- H01S 5/3013: {AIIIBV compounds}
- H01S 3/08027: {by a filter, e.g. a Fabry-Perot filter is used for wavelength setting}
- H01S 3/1055: one of the reflectors being constituted by a diffraction grating
- H01S 5/0612: {controlled by temperature}
- H04B 10/802: {for isolation, e.g. using optocouplers}
- H04J 14/0202: {Arrangements therefor}
- H01S: DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H04B: TRANSMISSION
- H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S)

## Abstract

A technique related to a semiconductor chip is provided. An optical gain chip is attached to a semiconductor substrate. An integrated photonic circuit is on the semiconductor substrate, and the optical gain chip is optically coupled to the integrated photonic circuit thereby forming a laser cavity. The integrated photonic circuit includes an active intra-cavity thermo-optic optical phase tuner element, an intra-cavity optical band-pass filter, and an output coupler band-reflect optical grating filter with passive phase compensation. The active intra-cavity thermo-optic optical phase tuner element, the intra-cavity optical band-pass filter, and the output coupler band-reflect optical grating filter with passive phase compensation are optically coupled together.

## Claims

### Claim 1

A method of configuring a semiconductor chip, the method comprising:
providing an optical gain chip attached to a semiconductor substrate; and
providing an integrated photonic circuit on the semiconductor substrate, the optical gain chip optically coupled to the integrated photonic circuit thereby forming a laser cavity, wherein the integrated photonic circuit comprises:
an active intra-cavity thermo-optic optical phase tuner element;
an intra-cavity optical band-pass filter; and
an output coupler band-reflect optical grating filter with passive phase compensation;
wherein the active intra-cavity thermo-optic optical phase tuner element, the intra-cavity optical band-pass filter, and output coupler band-reflect optical grating filter with passive phase compensation are optically coupled together.

### Claim 2 (depends on 1)

The method of claim 1, further comprising coupling a mode converter between the optical gain chip and the integrated photonic circuit.

### Claim 3 (depends on 1)

The method of claim 1, wherein the output coupler band-reflect optical grating filter with passive phase compensation is configured to reduce a net round trip phase change to within 4π over a temperature range.

### Claim 4 (depends on 3)

The method of claim 3, wherein the temperature range is 0-85° Celsius.

### Claim 5 (depends on 1)

The method of claim 1, wherein the output coupler band-reflect optical grating filter with passive phase compensation comprises a distributed reflector grating element.

### Claim 6 (depends on 5)

The method of claim 5, wherein the distributed reflector grating element has a smaller pitch at a first end and a wider pitch at a second end;
wherein the distributed reflector grating element is configured to shorten an effective cavity of the laser cavity with increasing temperature through increased index contract.

### Claim 7 (depends on 6)

The method of claim 6, wherein the distributed reflector grating element has an elongated direction and a width direction;
wherein the distributed reflector grating element changes in pitch along the elongated direction such that the distributed reflector grating element varies from the smaller pitch at the first end and increases to the wider pitch at the second end.