Analysis of gain suppression in undoped injection lasers

Journal Article · Wed Apr 01 00:00:00 EST 1981 · J. Appl. Phys.; (United States)

DOI:https://doi.org/10.1063/1.329064· OSTI ID:6774733

Yamada, M; Suematsu, Y

This paper gives an analysis and discussion of gain suppression in injection lasers which have an undoped active region and an index guiding structure. In previous papers, we used a semiclassical density-matrix analysis to show that an injection laser with an updoped active region has a nearly, but not perfectly, homogeneous (or uniform) gain property under operating conditions due to the mode coupling effects by phase synchronization of electrons to the lasing field. The gain of adjacent modes is well suppressed by the oscillating mode, and single-longitudinal-mode operation is obtained in undoped injection lasers. Such suppression depends closely on the spacial distribution of the resonating field and injected carrier density. The suppression effect is examined theoretically considering electronic intraband relaxation, effects from the standing wave of the lasing field, spatial diffusion of carriers, etc. When the relaxation time is larger than 3 x 10/sup -13/ sec, the gain shows ''hole burning,'' strong nonuniformity across the spectral or energy distributions, and the gain of some resonating modes is increased. Single-longitudinal-mode operation is not obtained in such a strongly inhomogeneous laser. When the relaxation time is smaller than 2 x 10/sup -13/ sec, the gain can be seen to be nearly homogeneous, and the gain of nonoscillating modes is sufficiently suppressed, that is, lower than that at threshold, because of the strong-mode-coupling effect. The relaxation time of GaAs is expected to be approximately 1 x 10/sup -13/ sec, implying 0.1% of excess suppression. The spatial distribution of the resonating field and induced ''spatial hole burning'' of carriers tends to increase the gain of higher transverse modes, but only weakly affects the fundamental transverse modes when the oscillating mode is the fundamental mode. It is then necessary to design the laser so that such higher transverse modes are cut off.

• Research Organization: Department of Electrical Engineering, Faculty of Technology, Kanazawa University, Kodatsuno, Kanazawa 920, Japan
• OSTI ID: 6774733
• Journal Information: J. Appl. Phys.; (United States), Vol. 52:4
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
SEMICONDUCTOR LASERS
GAIN
INHIBITION
MATHEMATICAL MODELS
CHARGE CARRIERS
COUPLING
DENSITY MATRIX
DIFFUSION
ELECTROMAGNETIC FIELDS
OSCILLATION MODES
RELAXATION
SPATIAL DISTRIBUTION
STANDING WAVES
SYNCHRONIZATION
THEORETICAL DATA
WAVEGUIDES
DATA
DISTRIBUTION
INFORMATION
LASERS
MATRICES
NUMERICAL DATA
SEMICONDUCTOR DEVICES
420300* - Engineering- Lasers- (-1989)