Transient-waveguide effects and lasing time delays in electron-beam-pumped semiconductor lasers

Journal Article · Thu Dec 01 04:00:00 EST 1977 · J. Appl. Phys.; (United States)

DOI:https://doi.org/10.1063/1.323621· OSTI ID:7208610

Garside, B K; Gouin, F; Shewchun, J

The dynamics of electron-beam-pumped semiconductor lasers are strongly affected by transient waveguiding. We have investigated the impact of such effects on the time delay from the start of the pumping pulse to the onset of laser emission in GaAs at liquid-nitrogen temperatures. Time delays were measured as a function of pump current density for three values of the electron-beam energy (20, 30, and 40 keV). Delays up to 200 nsec were observed which are approximately two orders of magnitude larger than the minority-carrier lifetime. A theoretical model is presented for the time-dependent variations of the optical confinement to account for such long delays. The time delay to threshold is determined not by the gain buildup but by the time required to sufficiently decrease the laser-mode diffraction loss in the active layer. Initially, the presence of gain results in a negative change of the refractive index with respect to the passive material. This is opposed by a growing positive index contribution due to the rise in temperature of the pumped layer. The latter eventually dominates, thereby confining the cavity modes. Under appropriate conditions, the ensuing reduction in loss determines the onset of lasing. The importance of the waveguide effect was confirmed by measurements on devices incorporating a permanent index step at the active-passive region interface.

• Research Organization: Departments of Engineering Physics and Physics, McMaster University, Hamilton, Ontario, Canada, L8S 4M1
• OSTI ID: 7208610
• Journal Information: J. Appl. Phys.; (United States), Journal Name: J. Appl. Phys.; (United States) Vol. 48:12; ISSN JAPIA
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
420300* -- Engineering-- Lasers-- (-1989)
ARSENIC COMPOUNDS
ARSENIDES
BEAMS
ELECTRON BEAMS
ENERGY-LEVEL TRANSITIONS
EXCITATION
GAIN
GALLIUM ARSENIDES
GALLIUM COMPOUNDS
LASERS
LEPTON BEAMS
OPTICAL PROPERTIES
PARTICLE BEAMS
PHYSICAL PROPERTIES
PNICTIDES
REFRACTIVITY
SEMICONDUCTOR DEVICES
SEMICONDUCTOR LASERS
TIME DEPENDENCE
TRANSIENTS
WAVEGUIDES