US 4,751,710 A · Semiconductor laser device

Abstract

A tunable semiconductor laser device includes a laser region and a tuning region, with a highly reflective surface formed on the cleaved vertical end facet of the tuning region for providing a reflectivity of 50% or more. The laser and tuning regions are formed on a common semiconductor substrate with the laser region having an active layer formed over the substrate, an optical waveguide layer adjacent the active layer and an electrode for carrying a drive current to the active region. The tuning region, adjacent the laser region on the substrate includes an optical waveguide which extends from the optical waveguide of the laser region, and a tuning current carrying electrode for injecting a tuning current across the waveguide layer of the tuning region. The tuning current alters the refractive index of the waveguide layer interface which changes the phase of the tuning region. Changing the tuning current varies the laser wavelength. The highly reflective end facet assures continuous wavelength tuning. The laser device may be incorporated into an integrated optical local oscillator comprising the laser device, a photodiode, a branched optical waveguide including an input port for mixing the output of the laser device and the light from the input port before being received by the photodiode.

Claims12

Dependent claims

A semiconductor laser device comprising:

a semiconductor substrate;
a laser region including an active layer formed over said semiconductor substrate for emitting radiation when excited, an optical waveguide layer formed below said active layer and having a band-gap greater than said active layer for waveguiding the radiation therein, a diffraction grating provided along said optical waveguide layer for coupling the radiation, and first electrode means formed over said active layer for feeding an injection current to said laser region to excite said active layer;
a tuning region formed over said semiconductor substrate including an optical waveguide layer extending from said optical waveguide layer of said laser region for waveguiding and constituting a part of the laser oscillation light path, and second electrode means formed over said optical waveguide layer of said tuning region for injecting an electric current across said optical waveguide layer of said tuning region;
and
reflective means formed on a vertical end facet of said optical waveguide layer of said tuning region for providing a reflectivity of 50% or above;
wherein said active region does not extend into said tuning region, no diffraction grating is provided along the optical waveguide layer of said tuning region, and the oscillation wavelength of said laser device is tuned by changing the electric current injected into said tuning region.

3 more elements

An integrated optical local oscillator comprising:

(a) a semiconductor substrate;
(b) a semiconductor laser device formed on said substrate, said laser device comprising;
a laser region including an active layer formed over said semiconductor substrate for emitting radiation when excited, an optical waveguide layer formed below said active layer and having a bandgap greater than said active layer for waveguiding the radiation therein, a diffraction grating provided along said optical waveguide layer for coupling the radiation, and first electrode means formed over said active layer for feeding an injection current to said laser region to excite said active layer,
a tuning region formed over said semiconductor substrate including an optical waveguide layer extending from said optical waveguide layer of said laser region for waveguiding and constituting a part of the laser oscillation light path, and second electrode means formed over said optical waveguide layer of said tuning region for injecting an electric current across said optical waveguide layer of said tuning region, and
reflective means formed on a vertical end facet of said optical waveguide layer of said tuning region for providing a reflectivity of 50% or above,
wherein sasid active region does not extend into said tuning region, no diffraction grating is provided along the optical waveguide layer of said tuning region, and the oscillation wavelength of said laser device is tuned by changing the electric current injected into said tuning region;
(c) a first optical waveguide on said substrate having first and second ends opposing to each other, said first end optically coupled to the end of said laser region remote from said tuning region;
(d) a second optical waveguide formed on said substrate, coupled to said first optical waveguide and having an end constituting an optical input signal port;
and
(e) a photodiode formed on said substrate and located to couple to said second end of said first optical waveguide.

7 more elements

An integrated optical local oscillator comprising:

(a) a semiconductor substrate;
(b) a semiconductor laser device formed on said substrate, said laser device comprising,
a laser region incluidng an active layer formed over said semiconductor substrate for emitting radiation when excited, an optical waveguide layer formed above said active layer and having a bandgap greater than said active layer for waveguiding the radiation therein, a diffraction grating provided along said optical waveguide layer for coupling the radiation, and first electrode means formed over said optical waveguide layer for feeding an injection current to said laser region to excite said active layer,
a tuning region formed over said semiconductor substrate including an optical waveguide layer extending from said optical waveguide layer of said laser region for waveguiding and constituting a part of the laser oscillation light path, and second electrode means formed over said optical waveguide layer of said tuning region for injecting an electric current across said optical waveguide layer of said tuning region, and
reflective means formed on a vertical end facet of said optical waveguide layer of said tuning region for providing a reflectivity of 50% or above,
wherein said active region does not extend into said turning region, no diffraction grating is provided along the optical waveguide layer of said tuning region, and the oscillation wavelength of said laser device is turned by changing the electric current injected into said tuning region;
(c) a first optical waveguide on said substrate having first and second ends opposing to each other, said first end optically coupled to the end of said laser region remote from said tuning region;
(d) a second optical waveguide formed on said substrate, coupled to said first optical waveguide and having an end constituting an optical input signal port;
and
(e) a photodiode formed on said substrate and located to coupled to said second end of said first optical waveguide.

7 more elements

Dependencies are inferred from the claim text.

Semiconductor laser device

Life of this patent

Semiconductor laser device

Life of this patent

Abstract

Claims12