Surface Emitting Quantum-Cascade Ring Laser Babichev, A. V.; Kolodeznyi, E. S.; Gladyshev, A. G. ...
Semiconductors (Woodbury, N.Y.),
07/2021, Letnik:
55, Številka:
7
Journal Article
Recenzirano
Quantum-cascade lasers with surface emission of radiation by means of a grating formed in the upper waveguide cladding layers by ion-beam milling are fabricated and studied. The active region of the ...laser heterostructure is based on the In
0.53
Ga
0.47
As/Al
0.48
In
0.52
As alloy alloys and uses a design with two-phonon resonance emptying of the lower level in the cascade. Room-temperature lasing near 7.9 μm is demonstrated for a laser with a ring-cavity diameter of 191 μm. The mode spacing in the lasing spectra corresponds to whispering-gallery modes.
Light-emitting devices of modern photonics are based on the semiconductor structures containing layers with various physical parameters. To preserve initial parameters during focused ion beam (FIB) ...lithography, it is necessary to take into account the processes of radiation defect formation. Radiation-induced defects in target play role of nonradiative recombination centers leading to photoluminescence (PL) quenching. In our work, the FIB impact on the photoluminescence were examined using PL spectroscopy of milled Al
0.18
Ga
0.82
As/GaAs double heterostructure. In order to exclude photoexcited carriers losses in emitter layer, an experiment with subbarrier photoexcitation was organized. Finally, we compare our experimental findings with theoretical data proposed by stopping and range of ions in matter (SRIM) calculation.
The paper presents a procedure for creating on GaAs(100) substrates textured surfaces by ion-beam etching with a focused beam. The possibility of flexibly controlling the shape and profile of the ...formed submicron elements of textured media is shown; this will later allow formation of textured surfaces of almost any complexity for realizing the surface radiation coupling from the waveguide. Original lithographic masks were developed, and 3D lithography was accomplished. The obtained lithographic patterns were controlled by the methods of optical, electron and atomic force microscopy.
The effect of ion energy in a focused ion beam in the range 12–30 keV on the formation depth of nonradiative recombination centers during etching of the Al
0
.
18
Ga
0
.
82
As/GaAs/Al
0
.
18
Ga
0
.
...82
As double heterostructure has been studied. It is shown that an increase in the ion energy leads to an increase in the concentration and propagation depth of radiation defects. It was found that during etching of focused ion beam with ion energies above 15 keV, the depth of formation of radiation defects exceeds 900 nm, which does not correspond to the calculations in the Stopping and Range of Ions in Matter.
We present an approach for the treatment of coupled-ridge lasers using focused ion beam (FIB) etching. We show experimentally that the FIB etching allows post-processing lateral mode tuning without ...deterioration of the main laser parameters.
The results of studies of ring quantum-cascade lasers with surface emission due to a second-order grating formed in the top cladding layers are presented. Surface emission near 7.85 μm with a low ...threshold current density (3.8 kA/cm
2
), in comparison with ridge quantum-cascade lasers of the same cavity length is demonstrated. The results of measurements of the intensity distribution of the near and far fields at different pumping levels are presented. The estimated value of the angle of beam extraction relative to the surface normal is in the range 5.7°–6.7°.
The ion-beam etching of AlGaAs/GaAs heterostructures gives rise to radiation defects and, as a result, leads to photoluminescence quenching. Annealing at 620°C in an atmosphere of As almost ...completely restores the quantum efficiency of photoluminescence in the case of radiation-induced defects lying at a distance of up to 150 nm from the heterointerface.
The results of studies of 7.5–8.0 μm range surface-emitting ring quantum-cascade lasers are presented. A second- order diffraction grating with a calculated coupling coefficient of ~9 cm
–1
is formed ...on the entire surface of the ring cavity by focused ion beam milling. Surface-emitting lasing at room temperature near 7.75 μm with a threshold current density of ~8 kA/cm
2
and an outer radius of the ring cavity of 202 μm is demonstrated. The results of studying the intensity distribution in the far-field near the normal to the surface showed the presence of two maxima. It is shown that the implemented coupling coefficient is not sufficient to ensure single-mode lasing in the studied ring quantum-cascade lasers.
We studied the influence of the focused ion beam milling of ridge waveguides on lasing parameters of edge-emitting lasers, based on a separate confinement double heterostructure. It is shown that ...there are three degrees of influence, according to the etching depth: modification of the waveguide properties only, a decrease in efficiency without changing the threshold current, and a simultaneous deterioration in the threshold current and efficiency with significant modification of the optical characteristics of the laser.
We study and compare optical microcavities formed by GaN planar nanowires. Nanostructures with structural defects such as stacking faults and without defects are considered. The behavior of an ...exciton localized in a stacking fault is considered. Different behavior of the photoluminescence intensity and the photoluminescence decay time is observed for the cases under consideration. Theoretical calculations show the localization of the field at the ends of the structure.
