# US 6,298,075 B1 · Optical apparatus and method for producing the same

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- Number: US 6,298,075 B1
- Document ID: US6298075B1
- Status: Granted
- Kind: B1
- Application number: 09/480,217
- Filed: 2000-01-10
- Granted: 2001-10-02
- Earliest claimed: 1995-11-16
- Assignees: Matsushita Electric Industrial Co., Ltd.
- Inventors: Yasuo Kitaoka; Kazuhisa Yamamoto; Makoto Kato; Kiminori Mizuuchi; Kenichi Nishiuchi
- Web page: https://patentgrep.com/patent/US6298075B1

## CPC

- H01S 5/0687: Stabilising the frequency of the laser
- G02B 6/42: Coupling light guides with opto-electronic elements
- G02B 6/4201: {Packages, e.g. shape, construction, internal or external details}
- G02B 6/4257: {having a supporting carrier or a mounting substrate or a mounting plate (G02B6/3648 takes precedence)}
- G02B 6/4272: {with mounting substrates of high thermal conductivity}
- H01S 5/06256: {with DBR-structure}
- G02B 6/4213: {the intermediate optical elements being polarisation selective optical elements (G02B6/27 takes precedence)}
- G02B 6/4215: {the intermediate optical elements being wavelength selective optical elements, e.g. variable wavelength optical modules or wavelength lockers (G02B6/4246 takes precedence)}
- G02B 6/4224: {using visual alignment markings, e.g. index methods}
- G02B 6/4271: {with thermo electric cooling}
- G02F 1/37: for second-harmonic generation {(G02F1/3532 takes precedence)}
- H01S 5/0092: {for nonlinear frequency conversion, e.g. second harmonic generation [SHG] or sum- or difference-frequency generation outside the laser cavity}
- H01S 5/02326: Arrangements for relative positioning of laser diodes and optical components, e.g. grooves in the mount to fix optical fibres or lenses
- H01S 5/02476: {Heat spreaders, i.e. improving heat flow between laser chip and heat dissipating elements}
- H01S 5/0612: {controlled by temperature}
- H01S 5/06837: {Stabilising otherwise than by an applied electric field or current, e.g. by controlling the temperature}
- 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
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS

## Abstract

A light generating apparatus includes: a submount; a semiconductor laser chip mounted on the submount; a substrate which is mounted on the submount and includes an optical waveguide; and a substance having a predetermined thickness which is disposed between the semiconductor laser chip and the substrate. In an oscillation wavelength stabilizing apparatus for a light source, the light source is a semiconductor laser which includes: an active region for providing gain; and a distributed Bragg reflection (DBR) region for controlling an oscillation wavelength. The apparatus includes a control section which monotonously varies, in a first direction, a DBR current to be input to the DBR region while detecting the oscillation wavelength of an output light of the semiconductor laser so as to detect a DBR current value Io corresponding to a predetermined wavelength value, and then monotonously varies the DBR current in a second direction which is opposite the first direction beyond the detected value Io, and then monotonously varies the DBR current in the first direction again to set the DBR current at the detected value Io, thereby fixing the oscillation wavelength of the semiconductor laser chip at the predetermined wavelength value.

## Claims

### Claim 1

A harmonic output stabilizing apparatus for a light source, wherein the light source is a short wavelength light source comprising:
a semiconductor laser including an active region for providing gain and a distributed Bragg reflection (DBR) region for controlling an oscillation wavelength; and a wavelength converting device made of non-linear optical crystal,
the apparatus comprising a control section for, upon detecting a DBR current value IO corresponding to a maximum value of the short wavelength light source, monotonously varying a DBR current away from, and then back to the detected value IO to remove from the detected value IO a hysteresis component with respect to the wavelength of the short wavelength light source.

### Claim 2

A harmonic output stabilizing apparatus for a light source, wherein the light source is a short wavelength light source comprising:
a semiconductor laser including an active region for providing gain and a distributed Bragg reflection (DBR) region for controlling an oscillation wavelength; and a wavelength converting device made of non-linear optical crystal,
the apparatus comprising a control section for fixing the oscillation wavelength of the semiconductor laser at a phase-matching wavelength of the wavelength converting device by monotonously varying, in a first direction, a DBR current to be input to the DBR region while detecting a harmonic optical output of the short wavelength light source and detecting a DBR current value IO corresponding to a maximum value of the harmonic optical output, and then monotonously varying the DBR current in a second direction which is opposite the first direction beyond the detected value IO, then monotonously varying the DBR current again to set the DBR current at the detected value IO int he only first direction.

### Claim 3

A harmonic output stabilizing apparatus for a light source, wherein the light source is a short wavelength light source comprising:
a semiconductor laser including an active region for providing gain and a distributed Bragg reflection (DBR) region for controlling an oscillation wavelength; and a wavelength converting device made of non-linear optical crystal,
the apparatus comprising a control section for fixing the oscillation wavelength of the semiconductor laser at a phase-matching wavelength of the wavelength converting device by monotonously varying, in a first direction, a DBR current to be input to the DBR region while detecting a harmonic optical output of the short wavelength light source and detecting and storing a DBR current value IO, corresponding to a maximum value of the harmonic optical output, and then independent of the harmonic optical output monotonously varying the DBR current in a second direction which is opposite the first direction beyond the stored value IO, and then monotonously varying the DBR current in the first direction again to set the DBR current to the stored value IO.

### Claim 4 (depends on 3)

An apparatus according to claim 3, wherein the wavelength converting device is a quasi-phase-matching wavelength converting device having a periodic domain inverted structure.

### Claim 5 (depends on 3)

An apparatus according to claim 3, wherein the wavelength converting device is an optical waveguide wavelength converting device.

### Claim 6 (depends on 3)

An apparatus according to claim 3, wherein the wavelength converting device is a bulk wavelength converting device.

### Claim 7 (depends on 3)

An apparatus according to claim 3, wherein the non-linear optical crystal comprises LiTaxNb1-xO3 (0≦x≦1).