Linear, nonlinear, and tunable guided wave modes for high-power (GaAl)As semiconductor lasers

Miscellaneous · Mon Jan 01 00:00:00 EST 1990

OSTI ID:6705441

Mehuys, D G

High power, coherent radiation from semiconductor lasers is attractive for such diverse applications as free space communication, optical data storage, and microsurgery. However, several factors conspire to prevent near ideal performance from broad area devices and laser arrays. Waveguides wider than a few microns support many lateral modes with poor gain discrimination. Consequently, such modes are easily mixed by perturbations in gain and refractive index caused by gain saturation, thermal gradients, and inhomogeneities due to imperfect crystal growth. This causes spatially localized modes, multimode operation, and reduced spatial coherence, all of which lead to farfield patterns broader than the diffraction limit. The influence of gain saturation on the lateral modes of broad area structures and laser arrays was investigated. Analytical and numerical techniques were developed to solve self consistently for mode shapes and propagation constants as a function of injected current density above threshold. In gain guided, quantum well lasers, the nonlinear broad area modes are observed to oscillate into narrow, single-lobed farfields which broaden only slightly with increased power output up to the 500 mW level. In contrast, the lateral modes of laser arrays were found to be unstable with increased current injection. Waveguides which are phase matched below threshold become detuned under the influence of gain saturation, so that interguide power transfer is reduced. This diminishes the injection locking bandwidth, and ultimately, the spatial coherence.

• Research Organization: California Inst. of Tech., Pasadena, CA (USA)
• OSTI ID: 6705441
• Resource Relation: Other Information: Ph.D. Thesis
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
SEMICONDUCTOR LASERS
MODE LOCKING
COHERENT RADIATION
CRYSTAL GROWTH
CURRENT DENSITY
REFRACTIVITY
STABILITY
TEMPERATURE GRADIENTS
WAVEGUIDES
ELECTROMAGNETIC RADIATION
LASERS
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
RADIATIONS
SEMICONDUCTOR DEVICES
SOLID STATE LASERS
426002* - Engineering- Lasers & Masers- (1990-)