A method for incorporating distributed feedback in a ridge waveguide laser by means of lateral gratings and a single growth step is discussed. The necessary Bragg condition for distributed feedback is satisfied by etching gratings along the ridge in the top confining layer of the laser on either side of the contact stripe. Both Fabry-Periot modes and a single emission peak away from the peak of the gain profile are observed in lasers with cleaved facets. The Bragg reflection emission peak does not shift with increasing drive current, which is characteristic of a distributed-feedback (DFB) laser. >

A distributed feedback ridge waveguide quantum well heterostructure laser

A distributed feedback semiconductor diode laser includes a substrate of n-type gallium arsenide having a channel along one surface thereof. A first clad layer of n-type aluminum gallium arsenide is on the surface of the substrate. The first clad layer fills the channel and has a planar surface. An active layer of undoped aluminum gallium arsenide is on the first clad layer and a first spacer layer of p-type conductivity aluminum gallium arsenide is on the active layer. A grating layer of p-type conductivity aluminum gallium arsenide is on the first spacer layer and has a second order grating therein which extends across the channel in the substrate. A second spacer layer of p-type conductivity aluminum gallium arsenide is on the grating layer and a second clad layer of p-type conductivity aluminum gallium arsenide is on the second spacer layer. The content of aluminum in the second clad layer varies across its thickness from an amount less than that in the second spacer layer at its junction with the second spacer layer to an amount equal to that in the second spacer layer. A cap layer of n-type conductivity gallium arsenide is on the second clad layer and a p-type conductivity contact region extends through the cap layer to the second clad layer over the groove in the substrate. Conductive contacts are on the contact region and a second surface of the substrate. The composition and thicknesses of the active layer, spacer layers and grating layer are such as to provide the output beam of the diode laser with a relatively low divergence angle of about 27°.

Distributed feedback-channeled substrate planar semiconductor laser

Results are presented on laterally-coupled distributed feedback (LC-DFB) ridge laser diodes. The epitaxial regrowth required in most distributed feedback devices is eliminated by using lateral evanescent coupling of the field to gratings etched along the sides of the ridge. A pulsed singlemode output power of 36 mW per facet was achieved at 937.5 nm with a sidemode suppression ratio (SMSR) of 30 dB for a 1.5 mm cavity length. A pulsed threshold of 11 mA, slope efficiency of 0.46 mW/mA per facet, and temperature sensitivity of 0.63 AA/ degrees C were measured for a 250 mu m cavity length LC-DFB.

InGaAs-GaAs-AlGaAs laterally-coupled distributed feedback (LC-DFB) ridge laser diode

InGaAs-GaAs-AlGaAs strained-layer distributed-feedback (DFB) ridge-waveguide lasers requiring a single metalorganic chemical vapor deposition (MOCVD) growth step are shown to operate in a single longitudinal mode up to 2.2*I/sub th/ with an antireflection (AR) coating applied to one facet under room temperature, pulsed conditions. A value of kL=0.33 has been determined from threshold gain calculations for coated and uncoated devices. Weak lateral optical confinement, provided by unpumped lateral gratings is demonstrated by the absence of antiguiding effects, and a real lateral index step of approximately 4*10/sup -3/ is determined from near-field emission patterns. >

Characterization of an InGaAs-GaAs-AlGaAs strained-layer distributed-feedback ridge-waveguide quantum-well heterostructure laser

In a first crystal growth step, a first cladding layer (11), an active layer (12), and an optical waveguide layer (14) are sequentially grown on a semiconductor substrate (10). A diffraction grating (21) is formed at a surface of the optical waveguide layer. In a second crystal growth step, a current block layer (17) is grown on the optical waveguide layer having the diffraction grating. The current block layer is selectively etched to expose the diffraction grating and thus to form a stripe groove. In a third crystal growth step, a second cladding layer (19) is grown on the diffraction grating inside the stripe groove and on the current block layer.

A method for producing a distributed feedback semiconductor laser device

A wavelength‐locked, AlGaAs channeled‐substrate‐planar distributed feedback laser has been made that operates to 40 mW pulsed. The Bragg grating is situated at the shoulders of the layers of AlGaAs and GaAs. Overall power efficiencies of 15% have been measured at 40 mW of output power.

N. Dinkel

Papers

Efficient AlGaAs channeled‐substrate‐planar distributed feedback laser