Hybrid narrow linewidth semiconductor laser with uniform FM response

• US 5,001,720 A
• Filed: 12/26/1989
• Issued: 03/19/1991
• Est. Priority Date: 12/26/1989
• Status: Expired due to Term

• Current Assignee: American Telephone & Telegraph Company (AT&T, Inc.), Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Original Assignee: AT&T, Inc.
• Inventors: Kuo, Chien Y., Ackerman, David A.
• Primary Examiner(s): EPPS, GEORGIA Y
• Application Number:
  US07/456,991
• Time in Patent Office: 448 Days
• Field of Search: 372/50, 372/45, 372/43, 372/44, 372/26, 372/28, 372/29, 372/32
• US Class Current: 372/50.1
• CPC Class Codes: H01S 5/0014 Measuring characteristics or properties thereof measuring techniques per se G01J, G01K, G01N, G01R
• CPC Class Codes: H01S 5/0618 Details on the linewidth enhancement parameter alpha
• CPC Class Codes: H01S 5/0625 in multi-section lasers
• CPC Class Codes: H01S 5/14 External cavity lasers H01S5/18 takes precedence; mode locking H01S5/065

Abstract

A hybrid laser arrangement is disclosed which is capable of providing an essentially uniform FM response and a relatively narrow linewidth signal, suitable for FM applications. The uniform FM response is obtained by inducing inhomogeneous linewidth enhancement through control of the bias currents applied to separate gain sections of a two-electrode Fabry-Perot device. Coupling of the two-electrode device to a narrowband resonant optical reflector provides for an extremely narrow signal linewidth.

Claims

1. A hybrid laser for FM applications comprising

a Fabry-Perot device including a first gain section and a second gain section with electrical isolation therebetween, the first section capable of being biased at a first predetermined current level I_f and the second section capable of being biased at a second predetermined current level I_b such that I_f is not equal to I_b ;

and

a narrowband resonant optical reflector coupled to the second gain section.

2. A hybrid laser as defined in claim 1 wherein I_f is greater than I_b.

3. A hybrid laser as defined in claim 1 wherein I_b is greater than I_f.

4. A hybrid laser as defined in claim 1 wherein the second gain section includes an anti-reflection coating disposed between the second gain section and the narrowband resonant optical reflector so as to suppress facet reflections of signals exiting said Fabry-Perot device and said narrowband resonant optical reflector.

5. A hybrid laser as defined in claim 1 wherein the electrical isolation comprises a groove formed in the Fabry-Perot device between the first and second gain sections.

6. A hybrid laser as defined in claim 1 wherein the electrical isolation comprises a dielectric material disposed between the first and second gain sections.

7. A hybrid laser as defined in claim 6 wherein the dielectric material comprises SiO₂.

8. A hybrid laser as defined in claim 1 wherein the electrical isolation comprises a current-blocking layer disposed between the first and second gain sections.

9. A hybrid laser as defined in claim 8 wherein the current blocking layer comprises Fe-doped InP.

10. A hybrid laser as defined in claim 1 wherein the Fabry-Perot device comprises an InP/InGaAsP double heterostructure laser.

11. A hybrid laser arrangement for FM applications comprising

an InP/InGaAsP double heterostructure laser including a first gain section and a second gain section, with electrical isolation therebetween, the first gain section for being biased at a predetermined current I_f and the second for being biased at a predetermined current I_b, wherein I_f >

I_b, with a modulating current I_mod, defines as a message signal, for being impressed upon the predetermined current I_b ; and

a narrowband resonant optical reflector coupled to the second gain section of the double heterostructure laser, with the second gain section including an anti-reflection coating so as to suppress facet reflections at said laser and said narrowband resonant optical reflector.