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Progress to a Gallium-Arsenide Deep-Center Laser
Yale University, P.O. Box 208284, New Haven, CT 06520-8284, USA
Received: 14 September 2009; in revised form: 9 October 2009 / Accepted: 20 October 2009 / Published: 22 October 2009
Abstract: Although photoluminescence from gallium-arsenide (GaAs) deep-centers was first observed in the 1960s, semiconductor lasers have always utilized conduction-to-valence-band transitions. Here we review recent materials studies leading to the first GaAs deep-center laser. First, we summarize well-known properties: nature of deep-center complexes, Franck-Condon effect, hotoluminescence. Second, we describe our recent work: insensitivity of photoluminescence with heating, striking differences between electroluminescence and photoluminescence, correlation between transitions to deep-states and absence of bandgap-emission. Room-temperature stimulated-emission from GaAs deep-centers was observed at low electrical injection, and could be tuned from the bandgap to half-the-bandgap (900–1,600 nm) by changing the electrical injection. The first GaAs deep-center laser was demonstrated with electrical injection, and exhibited a threshold of less than 27 mA/cm2 in continuous-wave mode at room temperature at the important 1.54 μm fiber-optic wavelength. This small injection for laser action was explained by fast depopulation of the lower state of the optical transition (fast capture of free holes onto deep-centers), which maintains the population inversion. The evidence for laser action included: superlinear L-I curve, quasi-Fermi level separations satisfying Bernard-Duraffourg’s criterion, optical gains larger than known significant losses, clamping of the optical-emission from lossy modes unable to reach laser action, pinning of the population distribution during laser action.
Keywords: laser action; stimulated emission; electroluminescence; hotoluminescence; gallium-arsenide; deep-centers
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MDPI and ACS Style
Pan, J.L. Progress to a Gallium-Arsenide Deep-Center Laser. Materials 2009, 2, 1599-1635.
Pan JL. Progress to a Gallium-Arsenide Deep-Center Laser. Materials. 2009; 2(4):1599-1635.
Pan, Janet L. 2009. "Progress to a Gallium-Arsenide Deep-Center Laser." Materials 2, no. 4: 1599-1635.