Separate Confinement Heterostructure Quantum-well Lasers Research Articles

Voltage distributions and nonoptical catastrophic mirror degradation in high power InGaAs/AlGaAs/GaAs lasers studied by Kelvin probe force microscopy

Kelvin probe force microscopy is used to observe the bulk potential redistribution across the high power InGaAs/AlGaAs/GaAs separate confinement heterostructure quantum-well laser diodes for a wide range of injection currents, including the lasing regime. By increasing the injection current, the development of a parasitic voltage drop is detected at initial calibration layers and the buffer layer of the laser structure. Catastrophic degradation of the laser mirror was observed at the level of injection current ∼19 times the threshold value. Atomic force microscopy images of the mirror revealed a 100 nm deep crater of maximum width ∼2.5 μm in the vicinity of the buffer/emitter interface. By combining the surface morphology results of the destructed mirror with those of Kelvin probe force microscopy in operating devices, it is concluded that the parasitic voltage drop is responsible for a substantial energy dissipation and the nonoptical degradation of the laser mirror.

Power rise in broad-waveguide diode laser with inclined facet

A method of transverse mode selection in high-power broad-waveguide separate confinement heterostructure quantum-well lasers by placing the front mirror at the angle other than the normal to the radiation propagation direction is proposed. Optimal values of facet inclination angles and widths and the refractive indices of the dielectric coating at which the fundamental guided mode dominates are found. The possibility of increasing the output power 1.2 times of a broad-waveguide separate confinement heterostructure quantum-well diode laser with inclined facet is shown.

14.3 W quasicontinuous wave front-facet power from broad-waveguide Al-free 970 nm diode lasers

Wide-stripe, 0.97 μm emitting Al-free InGaAs(P)/InGaP/GaAs broad-waveguide separate confinement heterostructure quantum-well lasers demonstrate a record value for quasicontinuous wave (QCW) output power: 14.3 W (100-μm-wide stripe, 100 μs-wide pulses); and reach catastrophic optical mirror damage (COMD) in QCW operation at an optical power density of 22.5 MW/cm2; that is, 40% higher than COMD levels in cw operation. The devices have low internal losses (αi=1 cm−1) and high external differential quantum efficiency (86% for 2-mm-long lasers), and exhibit only 10–20 °C temperature rises in the active region at 10 W QCW power. We also show that long-cavity, large-contact-area devices exhibit relatively little spectral broadening with increased output power.

Bipolar quantum-transport modeling of carrier injection into a SCH-quantum-well laser

A quantum mechanical model of carrier transport in separate confinement heterostructure (SCH) quantum-well lasers based on the Wigner function is presented for the first time. In the simulation, the three quantum Liouville equations with respect to the Wigner functions defined for electron, heavy-hole, and light-hole are solved simultaneously with the Poisson's equation to consider self-consistency in potential, As a simulation model, InGaAsP-InGaAs SCH quantum-well lasers are considered. The carrier injection into single and double quantum-well lasers is simulated. It is demonstrated that the amount of electrons and holes injected into the single quantum-well active layer is not equal in general if the quantum transport is considered. In the double quantum-well structure, the bottleneck phenomenon of heavy-hole injection into the second well and the quite different shape of heavy-hole density profiles in the two wells are simulated.

Carrier dynamics and gain saturation in quantum-well lasers

A Monte Carlo technique has been developed to investigate the carrier dynamics and static gain saturation in graded-index separate confinement heterostructure quantumwell laser structures. The calculated electron relaxation times and gain compression coefficient show good agreement with published experiments.

Threshold current reduction of GaInAs/GaInAsP/InP SCH quantum-well lasers with wire-like active region by using p-type substrates

The threshold current of GaInAs/GaInAsP/InP separate confinement heterostructure (SCH) quantum-well lasers with narrow (70-160-nm) wirelike active regions, which were fabricated by two-step LP-OMVPE growths and wet chemical etching, was much reduced ( >

Linewidth broadening of SCH quantum-well lasers enhanced by carrier fluctuation in optical guiding layers

A theoretical analysis of the spectral linewidth in separate-confinement heterostructure (SCH) quantum-well (QW) semiconductor lasers is given by taking into account the dynamics of the injected carriers in the optical guiding and barrier layers. The analytical result indicates that the linewidth tends to be abruptly broadened due to the dynamics of the carriers overflowing into the optical guiding layers, typically in a single-quantum-well structure. In addition, a superior effect on the linewidth reduction is predicted by adoption of a potential controlled (or modulation-doped) structure.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>