Temperature Analysis of Threshold Current in Infrared Vertical-Cavity Surface-Emitting Lasers (original) (raw)
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IEEE Journal of Quantum Electronics, 2000
Record-long emission wavelengths up to 1.3 m have recently been demonstrated from highly strained InGaAs-GaAs double-quantum-well (DQW) vertical-cavity surface-emitting lasers (VCSELs). The operation of InGaAs VCSELs at such long wavelengths has relied on a large detuning between the spectral positions of QW gain maximum and cavity resonance. This detuning also affects the high-temperature performance and temperature sensitivity of such devices. In this paper, we present and evaluate the threshold current-temperature characteristic of such lasers in relation to the gain-cavity detuning at room temperature (RT). For a near-zero gain peak offset from the emission wavelength at RT, the minimum threshold current is found at the temperature where the gain peak wavelength and the cavity resonance are approximately aligned. This is well in line with a common design rule for GaAs-based VCSELs. However, we show that this design rule fails in the case of larger gain-cavity misalignment at RT. Instead, a minimum threshold current is obtained considerably below the temperature of zero gain offset. We propose a conceptual model that relates the gain-cavity detuning at RT to the temperature sensitivity of the active region performance, which qualitatively describes the threshold current-temperature characteristic typical of VCSELs. The results demonstrate the importance of improving the temperature characteristic of the active region in order to reduce the high temperature sensitivity of devices with large detuning.
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.
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.
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
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.
IEEE Journal of Selected Topics in Quantum Electronics, 2000
In this paper, we present results from roomtemperature continuous-wave operation of 1.3-µm p-doped InAs-GaAs quantum-dot (QD) vertical-cavity surface-emitting lasers (VCSELs) with high T 0 of ∼510 K and low threshold current density of ∼65 A/cm 2 per QD layer. The highest output power from the device is over 0.74 mW. The temperature characteristics of the devices are investigated. It is demonstrated that deterioration in QD VCSEL performance due to self-heating results from the temperature sensitivity of QD emission, instead of mismatch between the gain wavelength and cavity modes. The real temperature at the QD VCSEL active region above threshold is estimated from the shift in lasing wavelength, which is in good agreement with calculations based on a self-consistent rate equation and thermal conduction model. The analysis shows that enhancing the carrier confinement in the QD wetting layer contributes to improving the saturated output power of the QD VCSEL.
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.
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 .
Micro-Optics, VCSELs, and Photonic Interconnects, 2004
We describe the development of long-wavelength InGaAs/GaAs vertical-cavity surface emitting lasers (VCSELs). Using highly strained double-quantum wells (DQWs) in combination with negative gain-cavity detuning we have been able to realise such VCSELs with emission wavelength up to 1300 nm. High-performance device characteristics include mWrange output power, mA-range threshold currents, 10 Gbit/s data transmission and very good temperature stability with continuous-wave operation up to at least 140°C. Singlemode emission is realised using an integrated mode filter consisting of a patterned silicon layer on the out-coupling mirror surface, yielding output power and threshold currents for 1270-nm devices of 1.2 -0.5 mW and 2.3 -0.6 mA, respectively, over a temperature interval of 10 -140°C. Multimode devices have been found to deliver more than 2 mW at 1290 nm. Preliminary lifetime measurements do not reveal any intrinsic reliability problems related to the highly strained quantum wells.
Semiconductors, 2006
Temperature dependence of the threshold current for VCSELs based on submonolayer InGaAs QDs is studied experimentally. It is shown that detuning between the lasing wavelength and the gain spectrum peak must be used for a correct description of the temperature characteristics of laser diodes. An expression for describing the temperature dependence of the VCSEL threshold current is proposed, which takes into account not only the reduction of the maximum gain of the active region with rising temperature, but also the effect of the temperature dependence of detuning.