Investigation of 1.3-μm GaInNAs vertical-cavity surface-emitting lasers (VCSELs) using temperature, high-pressure, and modeling techniques (original) (raw)
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IEEE Journal of Selected Topics in Quantum Electronics, 2003
We have investigated the temperature and pressure dependence of the threshold current ( th ) of 1.3 m emitting GaInNAs vertical-cavity surface-emitting lasers (VCSELs) and the equivalent edge-emitting laser (EEL) devices employing the same active region. Our measurements show that the VCSEL devices have the peak of the gain spectrum on the high-energy side of the cavity mode energy and hence operate over a wide temperature range. They show particularly promising th temperature insensitivity in the 250-350 K range. We have then used a theoretical model based on a 10-band k.P Hamiltonian and experimentally determined recombination coefficients from EELs to calculate the pressure and temperature dependency of th . The results show good agreement between the model and the experimental data, supporting both the validity of the model and the recombination rate parameters. We also show that for both device types, the super-exponential temperature dependency of th at 350 K and above is due largely to Auger recombination.
Optimization of GaInNAs quantum-well vertical-cavity surface-emitting laser emitting at 2.33 μm
Applied Physics A, 2013
In the present paper, a comprehensive computer simulation is used to determine optimal structure of the InPbased GaInNAs quantum-well (QW) active region and to investigate a possibility of reaching room-temperature (RT) continuous-wave (CW) single-fundamental-mode 2.33-µm operation of vertical-cavity surface-emitting laser (VCSEL) with such an active region. From among various considered InP-based active regions, the one with the Ga 0.15 In 0.85 N 0.015 As 0.985 /Al 0.138 Ga 0.332 In 0.530 As QW, i.e. with barriers lattice matched to InP, seems to be optimal for the 2.33-µm VCSEL performance. Its QW material is chosen for the required long-wavelength emission whereas its barrier is expected to ensure promising laser performance at room and higher temperatures. The latter is mostly connected with the QW conduction band offset equal in the above active region to as much as 413 meV, which is much larger than those of its possible lattice matched to InP competitors, e.g. 276 meV for the Ga 0.47 In 0.53 As barrier and 346 meV for the Ga 0.327 In 0.673 As 0.71 P 0.29 one. Our simulation reveals that from among various considered structures, a VC-SEL with a 4-µm-diameter tunnel junction and two 6-nm Ga 0.15 In 0.85 N 0.015 As 0.985 /Al 0.138 Ga 0.332 In 0.530 As QWs exhibits the lowest calculated threshold current of 0.88 mA. Its promising RT CW performance suggests that it may represent a very interesting alternative to GaSb-based VCSELs.
Applied Physics Letters, 2001
We report electromodulated reflectance studies on the band structure of a dilute-N ͑ϳ1%͒ ͑GaIn͒͑NAs͒/GaAs/AlAs vertical-cavity surface-emitting laser ͑VCSEL͒, as a function of temperature and incidence angle. The wide range of operating temperatures observed for this type of VCSEL ͑ϳ360 K here͒ is due to the reduced temperature variation of the effective band gap of the active ͑GaIn͒͑NAs͒ quantum wells, and broad gain. By comparing lasing properties and band structure we argue that the gain broadening is not simply due to alloy disorder but arises from a recently-proposed intrinsic property of ͑GaIn͒͑NAs͒: the existence of different band gaps for the five possible nearest-neighbor configurations of the N substitutional impurity.
Temperature Analysis of Threshold Current in Infrared Vertical-Cavity Surface-Emitting Lasers
IEEE Journal of Quantum Electronics, 2006
The temperature dependence of threshold current th in vertical-cavity surface-emitting lasers (VCSELs) can be approximated by the equation th ( ) = + ( min ) 2 , where min is the temperature of lowest th and are parameters, and temperature is . We compare the temperature dependence of threshold current in VCSELs with GaAs, InGaAs, and strain compensated InGaAs-GaAsP quantum wells. From our analysis we find the coefficient is related to the gain properties of the quantum well, and is shown to serve as a benchmark for the VCSEL temperature sensitivity. The incorporation of strain-compensated high-barrier GaAsP layers in the active region of 980-nm VCSELs is demonstrated to reduce the threshold dependence on temperature.
IEE Proceedings - Optoelectronics, 2005
The wafer of a 760 nm vertical-cavity surface-emitting laser (VCSEL), designed for oxygen sensing up to high temperatures, is investigated using photomodulated reflectance (PR). By varying the angle of incidence, the VCSEL cavity mode (CM) wavelength is tuned through the positions of two excitonic quantum well (QW) transitions. The PR is also measured over a large temperature range to determine when the QW ground-state transition is tuned with the CM. When tuned, the QW/CM PR lineshape becomes anti-symmetric, as predicted by theory. This occurs at 388 K, where the CM and QW wavelengths coincide at 760.7 nm. It is also observed that when tuned, the CM width measured in the reflectance spectrum is maximised. Temperature dependent device studies are also conducted on a 760 nm edge-emitting laser containing a similar active region as the VCSEL. It is found that up to 250 K the device behaves ideally, with the threshold current being entirely due to radiative recombination. However, as the temperature increases, electron leakage into the indirect X-minima of the barrier and cladding layers becomes increasingly significant. At 300 K, approximately 25% of the threshold current is found to be attributed to electron leakage and this increases to 85% at 388 K. The activation energy for this leakage process is determined to be 255^5 meV, indicating that electron escape from the QWs into the X-minima of the barrier and/or cladding layers is chiefly responsible for the device's poor thermal stability. These results suggest that VCSELs containing this active region are likely to suffer significantly from carrier leakage effects.
Temperature characteristics of InGaAs/GaAs vertical cavity surface emitting laser
Optoelectronics Letters, 2005
The temperature characteristics for the different lasing modes at 300 K of intracavity contacted In-GaAs/GaAs Vertical Cavity Surface Emitting Lasers(VCSELs) have been investigated experimentally by using the SV-32 cryostat and LD200205 test system. In combination with the simulation results of the reflective spectrum and the gain peak at different temperatures, the meas0rement results have been analyzed. In addition, the dependence of device size on temperature characteristics is discussed. The experimental data can be used to optimally design of VCSEL at high or cryogenic temperature.
Minimum temperature sensitivity of 1.55 μm vertical-cavity lasers at −30 nm gain offset
Applied Physics Letters, 1998
Double-fused vertical-cavity surface-emitting lasers ͑VCSELs͒ have demonstrated the highest temperature performance of any 1.5 m VCSEL, but further optimization is needed to reduce their temperature sensitivity. We present and analyze threshold current measurements of these devices between Ϫ90°C and 30°C stage temperature. Despite a zero gain peak offset from the emission wavelength at room temperature, the pulsed threshold current has its minimum near Ϫ50°C corresponding to about Ϫ30 nm gain offset. This is in contrast to a common VCSEL design rule. Temperature effects on the optical gain of the strain-compensated InGaAsP/InP active region are found to be the main cause for the disagreement. A design rule modification is proposed. Numerical simulation of an optimized 1.55 m VCSEL shows that gain offset improvements are counteracted by loss mechanisms. © 1998 American Institute of Physics. ͓S0003-6951͑98͒01915-9͔
2006
We present the static and dynamic simulation of a long-wavelength vertical-cavity surface-emitting laser (VCSEL) operating at around 1310 nm. The device consists of AlGaAs/GaAs distributed Bragg reflectors (DBRs) which are wafer-fused to both sides of the InP-based cavity with InAlGaAs quantum wells. A tunnel junction is used for current injection into the active region. The structure is simulated with a modified version of the commercial device simulator Synopsys Sentaurus Device. The fully-coupled two-dimensional electro-opto-thermal simulations use a microscopic physics-based model. Carrier transport is described by the continuity and Poisson equations and self-heating effects are accounted for by a thermodynamic equation. To obtain the opticalmodes, the wave equation is solved using a finite element approach. The optical gain model includes many-body effects. The equations are solved self-consistently. Calibrations of static (L-I, V-I curves) and dynamic characteristics (RIN) show good agreement with measurements at different temperatures. On this basis, the simulations reveal the critical factors that determine the modulation-current efficiency factor (MCEF) of the device.
Journal of Lightwave Technology, 2000
In this study, the gain-carrier characteristics of In 0.02 Ga 0.98 As and InAlGaAs quantum wells (QWs) of variant In and Al compositions with an emission wavelength of 838 nm are theoretically investigated. More compressive strain, caused by higher In and Al compositions in InAlGaAs QW, is found to provide higher material gain, lower transparency carrier concentration, and transparency radiative current density over the temperature range of 25-95 • C. To improve the output characteristics and high-temperature performance of 850-nm verticalcavity surface-emitting laser (VCSEL), In 0.15 Al 0.08 Ga 0.77 As/ Al 0.3 Ga 0.7 As is utilized as the active region, and a high-bandgap 10-nm-thick Al 0.75 Ga 0.25 As electronic blocking layer is employed for the first time. The threshold current and slope efficiency of the VCSEL with Al 0.75 Ga 0.25 As at 25 • C are 1.33 mA and 0.53 W/A, respectively. When this VCSEL is operated at an elevated temperature of 95 • C, the increase in threshold current is less than 21% and the decrease in slope efficiency is approximately 24.5%. A modulation bandwidth of 9.2 GHz biased at 4 mA is demonstrated.
Room-temperature operation of transistor vertical-cavity surface-emitting laser
Electronics Letters, 2013
We demonstrate the first room-temperature operation of a transistor vertical-cavity surface-emitting laser (T-VCSEL). Fabricated using an epitaxial regrowth process, the T-VCSEL is electrically a Pnp-type bipolar junction transistor and consists of an undoped AlGaAs/GaAs bottom DBR, an InGaAs triple-quantum-well (TQW) active layer, an Si/SiO2 dielectric top DBR, and an intracavity contacting scheme with three electrical terminals. The output power is controlled by the base current in combination with the emitter-collector voltage, showing a voltage-controlled operation mode. A low threshold base-current of 0.8 mA and an output power of 1.8 mW have been obtained at room temperature. Continuous-wave operation was performed up to 50°C .