Light absorption modulator and integrated semiconductor laser and modulator

• US 5,771,257 A
• Filed: 12/26/1996
• Issued: 06/23/1998
• Est. Priority Date: 12/26/1996
• Status: Expired due to Term

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Takiguchi, Tohru, Ishimura, Eitaro
• Primary Examiner(s): Bovernick, Rodney B.
• Assistant Examiner(s): LEUNG, QUYEN PHAN
• Application Number:
  US08/774,018
• Time in Patent Office: 544 Days
• Field of Search: 372/50, 372/45, 372/26, 359/248, 359/245, 385/14, 385/131, 385/1, 385/2
• US Class Current: 372/50.1
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G02F 1/0156 using free carrier absorption
• CPC Class Codes: G02F 1/01708 in an optical wavequide structure
• CPC Class Codes: H01S 5/0265 Intensity modulators intra-cavity modulators H01S5/0625
• CPC Class Codes: H01S 5/3054 p-doping
• CPC Class Codes: H01S 5/3409 special GRINSCH structures
• CPC Class Codes: H01S 5/34306 emitting light at a wavelength longer than 1000nm, e.g. InP based 1300 and 1500nm lasers
• CPC Class Codes: H01S 5/3434 with a well layer comprising at least both As and P as V-compounds

Abstract

A light absorption modulator includes a semiconductor substrate of a first conductivity type; a first cladding layer of the first conductivity type disposed on the substrate; an optical waveguide disposed on the first cladding layer and including a multiple quantum well optical waveguide layer through which light travels and first and second light confinement layers respectively disposed on opposed surfaces of the optical waveguide layer to confine light in the optical waveguide layer; and a second cladding layer of a second conductivity type, opposite the first conductivity type, disposed on the optical waveguide, one of the first and second cladding layers being n type, the one of the first and second light confinement layers that contacts the n type cladding layer being p type, and light traveling through the optical waveguide layer being modulated by applying an electric field to the optical waveguide layer. The electric field strength in the multiple quantum well optical waveguide layer when no reverse bias is applied to the modulator is reduced, whereby the rise time of the optical output from the modulator is reduced.

Claims

1. A light absorption modulator comprising:

a semiconductor substrate of a first conductivity type;

a first cladding layer of the first conductivity type disposed on the substrate;

an optical waveguide disposed on the first cladding layer and comprising a multiple quantum well optical waveguide layer through which light travels and first and second light confinement layers respectively disposed on opposed first and second surfaces of the optical waveguide layer for confining light in the optical waveguide layer; and

a second cladding layer of a second conductivity type, opposite the first conductivity type, disposed on the optical waveguide wherein one of the first and second cladding layers is n type, the one of the first and second light confinement layers that contacts the n type cladding layer is p type, and light traveling through the optical waveguide layer is modulated by applying an electric field to the optical waveguide layer.

2. The light absorption type modulator of claim 1 wherein the p type light confinement layer contacting the n type cladding layer comprises InGaAsP and has a carrier concentration larger than 1×

10¹⁷ cm^-3 and smaller than 1×

10¹⁸ cm^-3.

3. An integrated semiconductor laser and modulator comprising:

a semiconductor substrate of a first conductivity type;

a laser producing laser light; and

a light absorption modulator for modulating the laser light, the laser and modulator being monolithically integrated on the semiconductor substrate, wherein said light absorption modulator comprises;

a first cladding layer of the first conductivity type disposed on the substrate;

an optical waveguide disposed on the first cladding layer and comprising a multiple quantum well optical waveguide layer through which light travels and first and second light confinement layers respectively disposed on opposed first and second surfaces of the optical waveguide layer for confining light in the optical waveguide layer; and

a second cladding layer of a second conductivity type, opposite the first conductivity type, disposed on the optical waveguide wherein one of the first and second cladding layers is an n type, the one of the first and second light confinement layers that contacts the n type cladding layer is p type, and light traveling through the optical waveguide layer is modulated by applying an electric field to the optical waveguide layer.

4. The integrated semiconductor laser and modulator of claim 3 wherein the p type light confinement layer contacting the n type cladding layer comprises InGaAsP and has a carrier concentration larger than 1×

10¹⁷ cm^-3 and smaller than 1×

10¹⁸ cm^-3.