Reflector for semiconductor laser end-face and method of manufacturing the same

• US 5,339,326 A
• Filed: 08/30/1993
• Issued: 08/16/1994
• Est. Priority Date: 09/14/1992
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Yoshii Shigeo, Ohkawa, Kazuhiro, Tsujimura, Ayumu, Mitsuyu, Tsuneo
• Primary Examiner(s): Epps, Georgia Y.
• Application Number:
  US08/112,978
• Time in Patent Office: 351 Days
• Field of Search: 372/49, 372/99
• US Class Current: 372/49.01
• CPC Class Codes: H01S 5/028 Coatings ; Treatment of the laser facets, e.g. etching, passivation layers or reflecting layers

Abstract

The invention provides a reflector for a semiconductor device which oscillates in the region from the near infrared region to the visible and short wavelength region, and a method of manufacturing the reflector. With an RF magnetron sputtering apparatus, a dielectric reflector of deposited films is formed on an end-face of a ZnSe semiconductor laser device. The deposited films are formed by 3 repetitions of alternately depositing an SiO₂ film and a TiO₂ film which each has an optical thickness of a quarter of the oscillating wavelength of the semiconductor laser device such that a reflectance at the oscillating wavelength of the laser device is over 90%. The dielectric reflector improves current--light output characteristics of the laser device compared to a conventional semiconductor laser device provided with no dielectric reflector.

Claims

1. A reflector for an end-face of a semiconductor laser device comprising at least two dielectric films having a refractive index different from each other deposited on the end-face of a semiconductor laser device having an oscillating wavelength from 370 to 600 nm.

2. A reflector according to claim 1, wherein said semiconductor laser device is formed of a II-VI group compound.

3. A reflector according to claim 2, wherein said II-VI group compound is used as a single substance or a mixed crystal of at least one compound selected from zinc sulfide (ZnS), zinc selenide (ZnSe), zinc telluride (ZnTe), cadmium sulfide (CdS) and cadmium selenide ( CdSe ).

4. A reflector according to claim 1, wherein said dielectric films comprise a first film formed of at least one compound selected from the group consisting of calcium fluoride (CaF₂), magnesium fluoride (MgF₂), thorium (IV) fluoride (ThF₄), silicon dioxide (SiO₂) and aluminum oxide (A1₂ O₃), and a second film formed of at least one compound selected from the group consisting of zinc sulfide (ZnS), zirconlure (IV) oxide (ZrO₂), hafnium (IV) oxide (HfO₂), cerium (IV) oxide (CeO₂) and titanium (IV) oxide (TiO₂), and said first and second films are alternately deposited one over another.

5. A reflector according to claim 1 or 4, wherein said dielectric films each have an optical thickness equal to a quarter of an oscillating wavelength of said semiconductor laser device.

6. A reflector according to claim 1 or 4, wherein the number of said dielectric films alternately deposited is from 4 to 30.

7. A method of manufacturing a reflector for an end-face of a semiconductor laser device comprising the steps of alternately and continuously depositing at least two dielectric films on an end-face of a II-VI group compound semiconductor laser device in a vacuum chamber.

8. A method according to claim 7, wherein said dielectric films are deposited on a substrate kept at a temperature from 20°

to 150°

C.

9. A method according to claim 7 or 8, wherein the steps of alternately and continuously depositing at least two dielectric films comprise repetitions from 2 to 10 times of depositing a first dielectric film to an optical thickness equal to a quarter of an oscillating wavelength of said semiconductor laser device and depositing a second dielectric film to the same optical thickness as that of said first dielectric film.

10. A method according to claim 9, wherein said first dielectric film and said second dielectric film are formed of a first compound and a second compound, respectively, and said first and second compounds are selected from the pairs of SiO₂ and TiO₂ ;

SiO₂ and ZrO₂ ;

SiO₂ and ZnS;

MgF₂ and ZnS;

ThF₄ and ZnS;

MgF₂ and CEO₂ ;

CaF₂ and TiO₂ CaF₂ and HfO₂ ; and

A1₂ O₃ and TiO₂.

11. A method according to claim 9, wherein said first dielectric film is formed from a compound selected from the group consisting of CaF₂ MgF₂ ThF₄ SiO₂ and A1₂ O₃, and said second film is formed from a compound selected from the group consisting of ZnS, ZrO₂, HfO₂ , CeO₂ and TiO₂.