Semiconductor distributed feedback lasers with quantum well or superlattice gratings for index or gain-coupled optical feedback

Abstract

We introduce a semiconductor distributed feedback (DFB) in which the grating is fabricated out of quantum well (QW) or superlattice multilayers. This approach provides a very simple and effective scheme for achieving gain (loss)-coupled DFB lasers. The present idea was successfully demonstrated with a 1.55-μm wavelength 6-QW In0.6Ga0.4As (5 nm)/InGaAsP (band-gap wavelength=1.25 μm, 18.6 nm) separate confinement heterostructure DFB laser utilizing only a 2-QW In0.62Ga0.38As (4 nm)/InP (9.3 nm) as the grating.

First order gain-coupled GaInAs/GaAs distributed feedback laser diodes patterned by focused ion beam implantation

“…[5][6][7][8] The etching process can be used to modulate the thickness of absorptive layers 5,6 or of the active layers themselves. 7 Since the etching process creates a periodic modulation of the effective refractive index simultaneously with the gain grating, these devices are usually complex-coupled GC-DFB lasers.…”

Focused ion beam implantation for opto- and microelectronic devices

“…The technology used to fabricate these lasers up to now has been mainly based on lithography, etching of the active material, and overgrowth. Here the main problems of the processing include, e.g., the removal of contamination due to the lithography as well as overgrowth [1][2][3][4] …”

First-order gain-coupled (Ga,In)As/(Al,Ga)As distributed feedback lasers by focused ion beam implantation and in situ overgrowth

“…Gaincoupled distributed feedback lasers are currently under intense investigation 1-5 since they have several advantages over the conventional index-coupled DFB lasers. 2,4,11,12 The etching process is, e.g., used for a periodic thickness modulation of the active region 4 or for the thickness modulation of an absorption layer above or below the active layers. 1,6,7 The carrier density distribution along the resonator is defined by the structure itself.…”