Low-temperature operation of vertical cavity surface-emitting lasers (original) (raw)
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 .
Enhanced performance of offset-gain high-barrier vertical-cavity surface-emitting lasers
IEEE Journal of Quantum Electronics, 1993
The temperature dependence and power output of vertical-cavity surface-emitting lasers (VCSEL's) are of great importance when considering these devices for real applications. We have deliberately offset the peak wavelength of the quantum well from the wavelength of the device cavity mode so that they are aligned at elevated temperatures. The result of this design change is to produce an 8 pm diameter VCSEL capable of operation to 145"C, as well as CW operation of broad area (70 pm diameter) heat-sunk devices to record power levels. Fiber coupling experiments were also carried out, and a record 33 mW CW power was coupled to a multimode fiber.
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.
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.
Thermal effects in 2.x μm vertical-external-cavity-surface-emitting lasers
Journal of Applied Physics, 2012
The thermal behavior of vertical-external-cavity-surface-emitting lasers (VECSELs) is investigated. The temperature distribution in operating VECSELs has been experimentally determined for various operating conditions and different cooling schemes. The implementation of the thermoreflectance technique for the thermal analysis of VECSELs is demonstrated. This technique allows for high resolution mapping of a temperature increase resulting from the optical pumping of the VECSEL. The influence of a heatspreader on the VECSEL temperature is investigated. It is demonstrated that the use of an intracavity heatspreader bonded to the VECSEL chip causes a pronounced decrease of the temperature of the device. From the heat balance in the device, the lowering of the temperature of the VECSEL during operation is predicted. This is experimentally confirmed. V
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.
IEEE Photonics Technology Letters, 2000
Abstruct-We demonstrate for the first time the CW performance of AlGaAs-GaAs vertical-cavity surface-emitting lasers (VCSEL's) at cryogenic temperatures from 6 K to 200 K. By detuning the cavity mode with respect to the gain peak so that optimum dc lasing operation is achieved at -100 K, we find that this optimum lasing performance can be maintained down to temperatures as low as 6 K. Across a broad range of temperatures from 200 K to 6 K, the minimum threshold current of a 16-pm diameter VCSEL stayed below 4 mA, while its -3-dB modulation bandwidth increased by about 70% to 11 GHZ at 6 K, and the external slope efficiency is greater than 70%.
IEEE Journal of Quantum Electronics, 1993
Two-dimensional physical models for single-mode index guided vertical-cavity surface-emitting lasers (VCSEL's) are developed and compared with experimental measurements on state-of-the-art devices. Starting with the steady-state electron and photon rate equations, the model calculates the above threshold light-current (LI) characteristics. Included are temperature effects, spatial hole burning effects, carrier diffusion, surface recombination, and an estimation of optical losses. The model shows that the saturation of output power in the experimental devices is due to carrier leakage over the heterojunction and not simply the shifting of the gain peak relative to the cavity mode. Using the verified model new designs are analyzed, showing that output powers greater than 15 mW and power efficiencies above 20% should be achievable with existing processing technology.
Thermally induced local gain suppression in vertical-cavity surface-emitting lasers
Applied Physics Letters, 2000
Joule heating is one of the dominant mechanisms determining the transverse mode formation in vertical-cavity surface-emitting lasers at high injection currents. We give experimental evidence that in this operation regime, strong heating results in local gain suppression in the center of the laser, which overbalances the confining effect of thermal lensing, and thus favors the formation of high order modes. From our investigations of small aperture devices, we conclude that efficient heat removal is crucial for achieving single mode emission at high injection currents. © 2000 American Institute of Physics. ͓S0003-6951͑00͒03123-5͔
Ieee Photonic Technol Lett, 1996
We demonstrate for the first time the CW performance of AlGaAs-GaAs vertical-cavity surface-emitting lasers (VCSEL's) at cryogenic temperatures from 6 K to 200 K. By detuning the cavity mode with respect to the gain peak so that optimum dc lasing operation is achieved at-100 K, we find that this optimum lasing performance can be maintained down to temperatures as low as 6 K. Across a broad range of temperatures from 200 K to 6 K, the minimum threshold current of a 16-pm diameter VCSEL stayed below 4 mA, while its-3-dB modulation bandwidth increased by about 70% to 11 GHZ at 6 K, and the external slope efficiency is greater than 70%.
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
Vertical-cavity surface-emitting lasers: Design, growth, fabrication, characterization
IEEE Journal of Quantum Electronics, 1991
We have designed, fabricated, and tested verticalcavity surface-emitting lasers (VCSEL) with diameters ranging from 0.5 pm to >50 pm. The approaches we have taken have produced (not necessarily by us) the smallest, the lowest threshold, the highest quantum efficiency, and the highest modulation speed VCSEL's to date. The four principal sections of this paper-design issues, molecular beam epitaxial growth, fabrication, and lasing characteristics-are written by people who are closely involved in their development.
Heat Management in High-Power Vertical-External-Cavity Surface-Emitting Lasers
IEEE Journal of Selected Topics in Quantum Electronics, 2000
The thermal properties of a high-power verticalexternal-cavity surface-emitting laser (VECSEL) are studied experimentally, focusing on the generation, distribution, and removal of excess heat under extreme pumping conditions. Different heatspreading and heat-transfer approaches are analyzed. The performance of the device is optimized yielding a maximum emitted power beyond 70 W from a single spot. Finally, the potential for power-scaling in VECSELs and its restrictions are examined.
Vertical Cavity Surface Emitting Lasers as Sources for Optical Communication Systems: A Review
Journal of Nano Research (1661-9897), 2020
Next generation integrated photonic circuits will be dominated by small footprint devices with lower power consumption, low threshold currents and high efficiencies. Vertical Cavity Surface Emitting Lasers (VCSELs) having those attractive qualities has shown results to meet the next generation demands for optical communication sources. VCSELs applications are sensors, data com, optical communication, spectroscopy, printers, optical storage, laser displays, atomic optical clocks, laser radar, optical signal processing to name a few. This review centres around on the basic operation of semiconductor lasers, structure analysis of the devices and parameter optimisation for optical communication systems. This paper will provide comparisons on growth techniques and material selection and intends to give the best material realisation for nano optical sources that are up to date as used in optical communication systems. It also provides summarised improvements by other research groups in realisation of VCSELs looking at speeds, efficiency, temperature dependence and the device physical dimensions. Different semiconductor device growth methods, light emitting materials and VCSELs state of art are reviewed. Discussions and a comparisons on different methods used for realising VCSELs are also looked into in this paper.
Single-mode performance analysis for vertical-cavity surface-emitting lasers
Journal of Computational Electronics, 2007
In this work, the simulation of the single-mode stability in vertical-cavity surface-emitting lasers (VCSELs) is presented using a microscopic electro-opto-thermal model. Experimental data for oxide-confined VCSELs emitting at 850 nm with different contact metal designs are also available. It is shown that detailed models for the optical losses in the cavity consisting of outcoupling and absorption are required in order to explain the experiments. The role of cavity losses and spatial hole burning in the nonlinear electro-opto-thermal simulation framework is discussed in a quantitative manner.
Design and characterization of In/sub 0.2/Ga/sub 0.8/As MQW vertical-cavity surface-emitting lasers
IEEE Journal of Quantum Electronics, 1993
Abstruct-In this work, the device design, material characterization, and performance of optimized vertical-cavity surface-emitting lasers (VCSEL's) will be presented. The basic design goal was to increase the output power of the lasers without drastically increasing the low threshold current reported in earlier devices. The material characterization was performed by measuring in-plane lasers and broad-area VCSELs made from the same material as the small VCSEL's. For 10 pm square devices, outputs over 3 mW, device operation over 100°C, 6% wall-plug efficiency, threshold voltages under 3 V, and threshold currents under 2 mA are reported.
Journal of Physics and Chemistry of Solids, 1995
threshold current operation of vertical cavity surface emitting lasers (VCSELs) depends on a close match between the reflectivity resonance and the gain peak. We have used differential pressure and temperature tuning of these two spectra to quantify the required matching. The temperature in the VCSEL was increased by increasing the injected power. Increased temperature red shifts the gain peak at a rate five times that of the Fabry-Perot resonance resulting in a mismatch. At threshold the mismatch is 23 nm, reaches a value of 29 nm at the peak light output and at _ 50 nm lasing disappears. Increased mismatch is accompanied by a decrease in the gain at the laser wavelength, which is responsible for the laser quenching at high injected powers. Hydrostatic pressure shifts the gain peak to shorter wavelengths with respect to the FP resonance, without modifying the gain spectra. The mismatch was varied from 19 to -13 nm at 0.5 GPa. For positive mismatch the threshold current remained unchanged while for negative mismatch it increased drastically by about a factor of 4 at -13 nm when lasing disappears.
IEEE Journal of Quantum Electronics, 2019
III-N VCSELs undergo severe self-heating which limits the output optical power. This makes thermal management a critical design consideration. The three most common VCSEL structures (hybrid VCSELs, flip-chip VCSELs and ELOG VCSELs) have been studied using advanced self-consistent electro-opto-thermal numerical simulations. The key geometric and material parameters affecting the thermal resistance of these devices have been identified. Our simulations suggest that some of the proposed solutions and design modifications can increase the maximum optical output power by as much 100%. This manuscript also describes the correct method of using numerical simulation in device design-to predict trends and isolate the key factors affecting device performance.
Electrically pumped continuous-wave vertical-cavity surface-emitting lasers at ∼2.6 µm
In this paper, electrically pumped GaSb-based vertical-cavity surface-emitting lasers operating continuous wave at a record long emission wavelength of ∼2.6 μm are presented. Owing to the excellent thermal heat management, the devices exhibit single-mode operation up to a heat-sink temperature of 55 °C. Lateral current confinement and index guiding in the device are accomplished by utilizing the buried tunnel junction concept. Devices with aperture diameters of 6 μm show maximum output powers of 0.3 mW at room temperature with quantum efficiencies around 10%.
Thermal Equivalent Circuit Model for Coupled-Cavity Surface-Emitting Lasers
IEEE Journal of Quantum Electronics, 2015
In this paper, for the first time, an equivalent circuit model, including temperature effects, is introduced for coupledcavity vertical cavity surface-emitting lasers (CC-VCSELs). This model is based on a set of coupled rate equations for two carrier concentrations, a single longitudinal optical mode, and the temperatures of the cavities. By considering the main intrinsic physical processes inside the active layer, we modified the standard coupled rate equations to account for the effects of both the thermal-dependent laser gain and active layer carrier leakage current on CC-VCSELs performance. The presented model can be used in general purpose circuit simulators to study the influence of the thermal dependence of the laser gain spectrum, cavity resonance modes, and carriers leakage currents on the light-current (L-I) characteristics under different biasing conditions with a reasonable accuracy. Simulations results show that the threshold characteristic and linearity of the L-I curve are severely related to the temperature. On the other hand, the temperature variations cause the output optical power rollover. In addition, we verify that the variations of the threshold current with temperature have a parabolic form. Our results are in good agreement with the reported experimental data.