An improved technique for thermal resistance measurement of edge-emitting diode lasers using spontaneous emission spectra, collected through the opening in the
n
-contact within the range of ...operating currents, has been proposed. The advantage of the proposed technique is that systematic errors typical for measurements based on lasing spectra are excluded. The accuracy of the method was verified by measuring the dependence of the thermal resistance on the cavity length for diode lasers with 100 μm strip width. Obtained results are in good agreement with the model, and the minimum measurement error was ±0
.
1 K/W. The proposed technique can be used in metrological support of fabrication process of semiconductor lasers.
We propose an approach for encoding and transmitting information based on the use of a quantum dot laser, which, depending on the injection current, emits either one of two or simultaneously two ...spectral components, with different wavelengths. When the laser is modulated by current, each lasing line is detected by an independent photodiode, and thus the information is encoded by both the intensity of each line and its wavelength.
A post-growth technique aimed at spatial modification of facet reflectance of edge-emitting diode lasers has been proposed. It is based on the deposition of an anti-reflection coating and subsequent ...precise etching with a focused ion beam. The technique allowed suppressing of high-order lateral modes in 10 μm stripe lasers based on ten layers of InAs/InGaAs quantum dots.
Virtual cavity in distributed Bragg reflectors Shchukin, V A; Ledentsov, N N; Kalosha, V P ...
Optics express,
2018-Sep-17, 2018-09-17, 20180917, Letnik:
26, Številka:
19
Journal Article
Recenzirano
Odprti dostop
We show theoretically and experimentally that distributed Bragg reflector (DBR) supports a surface electromagnetic wave exhibiting evanescent decay in the air and oscillatory decay in the DBR. The ...wave exists in TM polarization only. The field extension in the air may reach several wavelengths of light. Once gain medium is introduced into the DBR a novel class of diode lasers, semiconductor optical amplifiers, light-emitting diodes, etc. can be developed allowing a new type of in-plane or near-field light outcoupling. To improve the wavelength stability of the laser diode, a resonant cavity structure can be coupled to the DBR, allowing a coupled state of the cavity mode and the near-field mode. A GaAlAs-based epitaxial structure of a vertical-cavity surface-emitting laser (VCSEL) having an antiwaveguiding cavity and multiple GaInAs quantum wells as an active region was grown and processed as an in-plane Fabry-Pérot resonator with cleaved facets. Windows in the top stripe contact were made to facilitate monitoring of the optical modes. Three types of the optical modes were observed in electroluminescence (EL) studies under high current densities > 1 kA/cm
. Mode A with the longest wavelength is a VCSEL-like mode emitting normal to the surface. Mode B has a shorter wavelength, emitting light at two symmetric lobes tilted with respect to the normal to the surface in the direction parallel to the stripe. Mode C has the shortest wavelength and shifts with a temperature at a rate 0.06 nm/K. Polarization studies reveal predominantly TE emission for modes A and B and purely TM for mode C in agreement with the theory. Spectral position, thermal shift and polarization of mode C confirm it to be a coupled state of the cavity mode and near-field DBR surface-trapped mode.
Using numerical simulation, the search for designs of asymmetric barrier layers (ABLs) in a laser diode with a GaAs waveguide emitting at a wavelength of λ = 980 nm is carried out. A pair of ABLs ...adjoining the active region on both sides blocks undesired charge-carrier flows and suppresses parasitic spontaneous recombination in the waveguide layers. Optimal designs of ABLs based on AlGaAsSb and GaInP for blocking electrons and holes, respectively, are proposed, which make it possible to reduce the parasitic recombination current down to less than 1% of the initial value. To suppress electron transport, an alternative structure based on three identical AlInAs barriers is also proposed. The GaAsP spacer layers separating these barriers from each other have different thicknesses. Due to this, the set of quasibound (resonant) states is formed in each spacer layer that is different from the set of states of the neighboring spacer layer. As a result, the resonant tunneling channels are blocked, and the parasitic electron flow is reduced by several tens of times in comparison with the case of spacers of identical thickness.
A systematic study of a series of InGaAs/GaAs lasers in the 1–1
.
3 μm optical range based on quantum wells (2D), quantum dots (0D), and quantum well-dots of transitional (0D/2D) dimensionality is ...presented. In a wide range of pump currents, the dependences of the lasing wavelength on the layer gain constant, a parameter which allows comparing lasers with different types of active region and various waveguide designs, are measured and analyzed. It is shown that the maximum optical gain of the quantum well-dots is significantly higher, and the range of lasing rawavelengths achievable in edge-emitting lasers without external resonators is wider than in lasers based on quantum wells and quantum dots.
Edge-emitting lasers with active regions based on novel InGaAs/GaAs quantum heterostructures of transitional dimensionality, i.e., quantum well-dots, which are intermediate in properties between ...quantum wells and quantum dots, are studied. It is shown that the rate of the lasing-wavelength blue shift decreases with increasing number of quantum well-dot layers in the active region and with increasing optical confinement factor as the cavity length decreases. In a laser with 10 quantum well-dot layers, the lasing-wavelength position remains within the limits of the fundamental optical transition down to the smallest cavity lengths (100 μm). In devices with a single quantum well-dot layer and/or with a low optical confinement factor, lasing directly switches from the ground state to waveguide states omitting excited states below ≤200 μm. Such an effect has not been observed in quantum-well- and quantum-dot lasers and can be attributed to the abnormally low density of excited states in quantum well-dots.
We have studied superluminescent diodes with simplified design and active region based on 5 or 7 layers of InGaAs/GaAs quantum well-dots (QWDs). Emission peaks of the individual QWD layers are ...shifted with respect to each other by 15–35 nm to provide as wide as possible emission line in a superluminescent mode with central wavelength of about 1 μm without significant spectral dips. For superluminescent diodes with the active region based on 5 and 7 QWD layers, the maximal value of full width at half maximum of emission spectrum was 92 and 103 nm respectively.
The influence of InGaAlAs waveguide composition on the photoluminescence and electroluminescence of 1550 nm spectral range heterostructures based on thin strained In
0
.
74
Ga
0
.
26
As quantum wells ...has been studied. An approach is proposed that allows based on the analysis of electroluminescence to carry out a comparative analysis of the deferential gain in fabricated laser diodes. It is shown that decrease of the molar fraction of aluminum in waveguide InGaAlAs layers matched in lattice constant with InP leads to falling of integrated photoluminescence intensity, however, laser diodes with In
0
.
53
Ga
0
.
31
Al
0
.
16
As waveguide layers demonstrate a higher differential gain compared to laser diodes with In
0
.
53
Ga
0
.
27
Al
0
.
20
As waveguide.
We report room temperature injection lasing in the yellow-orange spectral range (599-605 nm) in (Al
Ga
)
In
P-GaAs diodes with 4 layers of tensile-strained In
Ga
P quantum dot-like insertions. The ...wafers were grown by metal-organic vapor phase epitaxy side-by-side on (811), (211) and (322) GaAs substrates tilted towards the direction with respect to the (100) surface. Four sheets of GaP-rich quantum barrier insertions were applied to suppress leakage of non-equilibrium electrons from the gain medium. Laser diodes having a threshold current densities of ~7-10 kA/cm
at room temperature were realized for both (211) and (322) surface orientations at cavity lengths of ~1mm. Emission wavelength at room temperature ~600 nm is shorter by ~8 nm than previously reported. As an opposite example, the devices grown on (811) GaAs substrates did not show lasing at room temperature.
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