Showing papers on "Quantum dot laser published in 1979"
NEC1
TL;DR: In this paper, a numerical analysis has been carried out on the behavior of semiconductor injection lasers with a stripe geometry double-heterostructure, taking into account spatial hole-burning and its effect on the waveguiding.
Abstract: A numerical analysis has been carried out on the behavior of semiconductor injection lasers with a stripe geometry double-heterostructure, taking into account spatial hole-burning and its effect on the waveguiding. It is shown that spatial hole-burning, the negative dependence of refractive index eta on the excited carrier density n (d_{eta}/ dn , and the lack of complete symmetry in any real laser structure are the three critical factors responsible for the lateral mode instability leading to such anomalous behaviors these lasers exhibit as a "kink" in the light output versus current relation and the lateral shift in the emission spot. Effects of rigid refractive index and gain-loss profiles built into the laser crystal on the mode stability have been examined, and conditions for kink-free, single lateral mode oscillations have been investigated.
112 citations
TL;DR: A condition for single longitudinal mode operation (SMO) of index-guided injection lasers is given theoretically and supported by experiment in this article, where the transverse higher modes must be cut off by using a narrow-width index-guiding waveguide.
Abstract: A condition for single longitudinal mode operation (SMO, for short) of index-guided injection lasers is given theoretically and supported by experiment. For SMO, the transverse higher modes must be cut off by using a narrow-width index-guiding waveguide. Inclusion of the spontaneous emission into the lasing field must be reduced by using a thinner active region. In terms of the impurity concentration of the active region, the undoped case is the most stable for temperature variation. A heavily doped active region may also produce SMO. The thermal resistance must be reduced to increase temperature stability. MO with a fixed lasing wavelength is experimentally obtained by temperature control up to an injection current of twice threshold.
102 citations
TL;DR: In this article, a theoretical and experimental description of the lateral mode behavior in oxide-insulated stripe geometry laser with stripe width below 8 μm is given, based on the waveguiding effects of carriers injected into the active region, and includes accurate, selfconsistent solutions to the waveguide and carrier distribution equations.
Abstract: A theoretical and experimental description of the lateral mode behavior in oxide-insulated stripe geometry lasers with stripe width below 8 μm is given. The analysis is based on the waveguiding effects of carriers injected into the active region, and includes accurate, self-consistent solutions to the waveguide and carrier distribution equations. In agreement with experiment, wide ( \geq12 \mu m) near-field patterns and non-Gaussian far-field patterns are found for the fundamental mode. As the current is increased above threshold, the near fields become progressively wider and the far fields develop a twin peak structure. The optical properties of the output are dominated by a one-dimensional analog of spherical aberration. It is shown that high pulsed output power may be obtained in fundamental lateral mode without incurring catastrophic facet damage.
69 citations
TL;DR: In this article, a GaAlAs DH-laser hybrid device that compensates for temperature variations and laser degradation is described, with a projected room-temperature median lifetime of 6 \times 10^{5} h.
Abstract: A GaAlAs DH-laser hybrid device is described that compensates for temperature variations and laser degradation. Lifetesting in a 55°C ambient for over a year yields a projected room-temperature median lifetime of 6 \times 10^{5} h. Lasers having no aluminum in the active layer have a median lifetime 70 times smaller.
35 citations
TL;DR: In this article, the excitation-dependence of the resonant frequency intrinsic to a semiconductor laser is analyzed in terms of a spatially uniform laser model which takes into account radiative and nonradiative recombination as well as spontaneous emission into the lasing modes.
Abstract: The excitation-dependence of the resonant frequency intrinsic to a semiconductor laser is analyzed in terms of a spatially uniform laser model which takes into account radiative and nonradiative recombination as well as spontaneous emission into the lasing modes. The analysis reveals that the frequency of the resonance excited by internal quantum noise approaches a minimum value as the excitation level approaches threshold in contradiction to the behavior expected from a small-signal analysis of the external modulation spectrum or the relaxation oscillations. This distinctly different behavior of the noise-excited resonance is shown to result from the presence of noise fluctuations in the optical field, which are sensed only by the noise-excited spectrum. Experimental observations made with a stripe-geometry (AlGa)As double-heterostructure laser confirm the predicted behavior of the noise-excited resonant frequency in the near-threshold regime.
25 citations
TL;DR: In this paper, the operation of an external-cavity CW double-heterojunction GaAs injection laser that can be electrooptically tuned rapidly over a large spectral range (∼ 50 A) and experiments demonstrating the feasibility of FM optical communications using electronically tunable semiconductor lasers and CW and mode-locked dye lasers are presented.
Abstract: We report the operation of an external-cavity CW double-heterojunction GaAs injection laser that can be electrooptically tuned rapidly over a large spectral range (∼ 50 A) and experiments demonstrating the feasibility of FM optical communications using electronically tunable semiconductor lasers and CW and mode-locked dye lasers. An experiment on binary pulse-code FM optical communication is also reported and discussed.
20 citations
TL;DR: In this article, the origins of transverse mode instability, methods of mode control, and the lasing characteristics of single transverse modes are discussed, and a GaA1As injection laser is discussed.
Abstract: Mode stabilization in GaA1As injection lasers is discussed. The origins of transverse mode instability, methods of mode control, and the lasing characteristics of single transverse mode lasers are the main subjects.
17 citations
TL;DR: In this paper, Cavity and reflector lengths were determined for single-mode single-ended operation over a CW optical-output power range of 5-50 mW, assuming an internal quantum efficiency of 90 percent, external quantum efficiencies for the optimized structures were found to range from 14.1 percent to 57.8 percent.
Abstract: Optimal designs are developed for large optical cavity (LOC)-type GaAs-distributed Bragg reflection lasers. Cavity and reflector lengths are determined which allow single-mode single-ended operation over a CW optical-output power range of 5-50 mW. Assuming an internal quantum efficiency of 90 percent, external quantum efficiencies for the optimized structures are found to range from 14.1 percent (for 5-mW output) to 57.8 percent (for 50-mW output). Threshold current densities are found to remain less than 1000 A/cm^2 over the entire optical output range considered.
15 citations
TL;DR: In this article, mode locking of semiconductor injection lasers is considered theoretically through the use of rate equations, and the laser losses, rather than the material gain bandwidth, are found to limit the pulse width.
Abstract: Mode locking of semiconductor injection lasers is considered theoretically through the use of rate equations. The laser losses, rather than the material gain bandwidth, are found to limit the pulse width. Estimates for power output and the effects of spontaneous emission can be made
14 citations
Patent•
12 Jul 1979TL;DR: In this paper, a phase-locked laser array comprised of a plurality of stacked emitting or active regions which are in sufficiently close contact to each other is proposed, where light from each active region is coupled to the light from the adjacent active regions to form a phase locked laser array with low composite beam divergence.
Abstract: A laser array comprised of a plurality of stacked emitting or active regions which are in sufficiently close contact to each other that light from each active region is coupled to the light from the adjacent active regions to form a phase-locked laser array with low composite beam divergence perpendicular to the plane of the rectifying junction of the active regions.
12 citations
TL;DR: In this paper, the influence of laser length, stripe width w and facet reflectivity R on various lasing characteristics of AlGaAs-GaAs double hetero-structure semiconductor lasers is discussed experimentally, and the results are theoretically considered on the basis of the rate equations.
Abstract: The influence of laser length l, stripe width w and facet reflectivity R on various lasing characteristics of AlGaAs–GaAs double hetero-structure semiconductor lasers is discussed experimentally, and the results are theoretically considered on the basis of the rate equations. It becomes clear that short cavity lasers with the high reflective facets are suitable for single longitudinal mode oscillation.
TL;DR: In this article, the authors describe the energy levels and transition probabilities of solid-state lasers and show that the spectral range of solid state lasers extends from approximately 0.5 to 3.0 pm, a wavelength factor of six.
Abstract: Publisher Summary This chapter describes the energy levels and transition probabilities of solid-state lasers. The spectral range of solid-state lasers extends from approximately 0.5 to 3.0 pm, a wavelength factor of six. It is observed that for solid-state lasers, population inversion is achieved by optical pumping and is dependent upon the absorption spectrum of the laser ion in the host, the spectral match of this spectrum with the spectrum of the pumping source, the lifetime of the upper laser level, which determines the pumping rate required, and the quantum efficiency. The threshold for laser action involving vibronic transitions depends on the transition probability and the thermal Boltzman population in the terminal level. Optical transitions between electronic states of laser ions in solids, either that used for pumping or for stimulated emission, are predominantly of electric-dipole nature. Paramagnetic ions from several transition groups have been used for solid-state lasers. It is found that solid-state laser hosts include both ordered and disordered materials.
TL;DR: In this article, the mode competition in pulsed AlGaAs lasers, which oscillate in a few longitudinal modes, is studied by time resolved spectrum measurement, where only a single mode oscillates at a time; other modes are suppressed.
Abstract: Mode competition in pulsed AlGaAs lasers, which oscillate in a few longitudinal modes, is studied by time resolved spectrum measurement. Only a single mode oscillates at a time; other modes are suppressed. Mode transition time is 30 ns which coincides with theoretical evaluation.
TL;DR: Pulsed semiconductor heterojunction lasers, simulating ruby (693 nm) and neodymium (1060 nm) were fabricated and the peak power was 1.5-2 W.
Abstract: Pulsed semiconductor heterojunction lasers, simulating ruby (693 nm) and neodymium (1060 nm) lasers, were fabricated. The peak power was 1.5--2 W. The pulse duration could be varied from 5 nsec to 1 ..mu.. sec.
TL;DR: In this paper, the dependence of the quantum efficiency on the length of the active region and the distribution of the intensity along the laser axis were determined experimentally for a distributed-feedback semiconductor laser pumped by an electron beam.
Abstract: Dependences of the quantum efficiency on the length of the active region were determined experimentally for a distributed-feedback semiconductor laser pumped by an electron beam. The output radiation was coupled out through the surface or end of a waveguide. The dependences obtained were compared with circulations. It was found that the efficiency of coupling out of the radiation through the surface of the waveguide could be greater than the efficiency of coupling out through its end. A relationship was found between the dependence of the quantum efficiency on the length of the active region and the distribution of the intensity along the laser axis.
TL;DR: In this paper, the authors describe the different aspects of semiconductor diode lasers and the gain coefficient and threshold condition for semiconductor diodes, and the relative importance of these factors depends on the applied voltage.
Abstract: Publisher Summary This chapter describes the different aspects of semiconductor diode lasers. Semiconductor lasers cover a spectral range extending from the far infrared to the visible. The incorporation of heterojunctions in injection provides, under favorable circumstances, device performance approaching the theoretical limits of the semiconductor. It is found that in the homojunction laser, there are no abrupt refractive index steps for optical confinement or significant potential energy barriers for carrier confinement. Complications are frequently introduced by interfacial defects and the current–voltage characteristics are controlled by a combination of thermal injection over the barrier, tunneling through the barrier, and space-charge region recombination. The relative importance of these factors depends on the applied voltage. The basic heterojunction laser is a three-layer dielectric slab with constant refractive index in each layer at the lasing energy, where the recombination or active region is bracketed by two higher bandgap regions. The gain coefficient and threshold condition for semiconductor diode lasers are also elaborated.