Quantum well lasers tunable by long wavelength radiation (original) (raw)
Related papers
The Physics of the Quantum Well Laser
Physica Scripta, 1987
This paper reviews some of the properties of quantum well lasers (QWLs), with emphasis on the two-dimensional origins of these. It is shown that two main effects determine the lowering of threshold current, namely the diminished density of states (DOS) (favourable factor) and the diminished optical confinement (unfavorable factor). The good operation of GaAs-GaAlAs QWLs also relies on more subtle effects such as the square 2D DOS, the enhanced optical matrix element, the high quantum efficiency. .. The poor operation of GaInAs based quantum well lasers is due to the detrimental Auger effect which is larger than in 3D lasers because of the higher carrier densities at which QWLs operate. Several other useful properties of QWLs in the performance (high-frequency, narrow-line) and manufacturing fields are discussed. Problems and advantages of 1 and OD quantum-wire and quantum-box lasers are briefly evaluated.
Journal of Physics: Conference Series, 2016
A model for calculating the operating characteristics of semiconductor quantum well (QW) lasers is presented. The model exploits the condition of global electroneutrality, which includes the charge carriers both in the two-dimensional (2D) active region (QW) and bulk waveguide region (optical confinement layer-OCL). The charge of each sign in the OCL is shown to be significantly larger than that in the QW. As a result of this, (i) the global electroneutrality condition reduces to the condition of electroneutrality in the OCL and (ii) the local electroneutrality in the QW can be strongly violated, i.e., the 2D electron and hole densities in the QW can significantly differ from each other.
Spontaneous emission control in quantum well laser diodes
Optics Express, 1998
Spontaneous emission control has been achieved in GaAs/AlGaAs quantum well lasers by the use of Bragg reflectors to define a micro-cavity perpendicular to the quantum wells. The room temperature emission is inhibited whilst below 130K there is an enhancement. These changes to the spontaneous recombination process directly effect the threshold current producing a 25% reduction at room temperature. Theoretical modeling of the lasers is in agreement with the experimental results and highlights the effect of the micro-cavity in altering the overlap of the electromagnetic field with the quantum well dipole oscillators.
The European Physical Journal B, 2011
In this work are studied the intense laser effects on the impurity states in GaAs-Ga1−xAlxAs quantum wells under applied electric and magnetic fields. The electric field is taken oriented along the growth direction of the quantum well whereas the magnetic field is considered to be in-plane. The calculations are made within the effective mass and parabolic band approximations. The intense laser effects have been included through the Floquet method by modifying the confinement potential associated to the heterostructure. The results are presented for several configurations of the dimensions of the quantum well, the position of the impurity atom, the applied electric and magnetic fields, and the incident intense laser radiation. The results suggest that for fixed geometry setups in the system, the binding energy is a decreasing function of the electric field intensity while a dual monotonic behavior is detected when it varies with the magnitude of an applied magnetic field, according to the intensity of the laser field radiation.
Modulation of quantum well lasers by short optical excitation: energy and spatial dependent effects
IEEE Photonics Technology Letters, 1995
We describe an energy-resolved and spatially selective time domain technique for optically excited measurements of diode laser modulation responses. We report application of the technique to a study of an InGaAs-GaAs quantum well laser. We emphasize the significance of the spatial characteristics of the excitation in resolving effects related either solely to the active region or to the entirety of the laser structure.
Theory of reduced threshold current density in GaAs/AlGaAs quantum well lasers
Superlattices and Microstructures, 1990
It has recently been demonstrated that (111) GaAs/AlGaAs quantum well lasers can have a lower threshold current density than equivalent (001) lasers. We have used the envelope function method to calculate the hole confinement energies and valence subband dispersion energies of (111) and (001) quantum wells of varying width. We find that the differences in the vlrlence subband dispersion can account fully for the measured differences in threshold current densities. The heavy-hole mass is significantly larger dong (111) than aIong the conventional (001) growth direction. This increases the number of heavy-hole confined states for a given weJI width. Away from the zone centre, the subband dispersion in the well plane shows less mixing between heavy-and light-hole bands than for (001) growth and, in thin we&, the highest subband has a low in-plane effective mass over a greater energy range, resulting in a reduced density of states at the valence band maximum. Laser gain calculations show that this enhanced light-hole behaviour can explain the reduction in threshold current density of (111) lasers compared to equivalent (001) lasers, in good agreement with experimental observation. We also calculate optical matrix elements for TE and TM modes and find that in thin (111) lasers, an improved selection of TE over TM modes is possible, due mainly to the different subband orderings in the two growth directions. This leads to the elimination in (111) lasers of the TM jump of the laser mode observed in some (001) lasers and its replacement by a TE jump, in agreement with experimental observations.
Hot electrons and curves of constant gain in long wavelength quantum well lasers
Optics Express, 1998
In long wavelength quantum well lasers the effective electron temperature (T e ) is often a strong function of the pump current and hence the T e correlates with the carrier concentration n in the active region. On the other hand, the material gain g in the active layer depends on both variables, g=g(n,T e ). We discuss a convenient way of analyzing this situation, based on considering the contours of constant gain g on the surface g(n,T e ). This is qualitatively illustrated with two model examples involving quantum well lasers, the long-wavelength quantum well laser with current dominated by the Auger recombination and the unipolar quantum cascade laser. 1998 Optical Society of America OCIS codes: (140.5960) Semiconductor lasers; (230.5590) Quantum-well devices 2. V. B. Gorfinkel and S. Luryi, "Fundamental limits for linearity of CATV lasers", J. Lightwave Technol. 13, 252-260 (1995); http://www.ee.sunysb.edu/\~serge/133.html 3. M. Silver, E. P. O'Reilly, and A. R. Adams, "Determination of the wavelength dependence of Auger recombination in long-wavelength quantum-well semiconductor lasers using hydrostatic pressure", IEEE J. Quantum Electron. 33, 1557-1566 (1997).