IEEP Spagnolo 2003 QCL-thermal micro-probe1 (original) (raw)
Related papers
Thermal characteristics of quantum-cascade lasers by micro-probe optical spectroscopy
Iee Proceedings-optoelectronics, 2003
The facet temperature profile and the thermal resistance of operating quantum-cascade lasers (QCLs) have been assessed using a microprobe band-to-band photoluminescence technique. Substrate-side and epilayer-side-mounted QCLs based on GaInAs/AlInAs/InP and GaAs/AlGaAs material systems have been compared. The dependence of the thermal resistance on the CW or pulsed injection conditions and its correlation with the output power have been studied. These results were used as inputs for a two-dimensional heat-diffusion model which gives the heat fluxes and the thermal conductivity of the active regions, in order to design QCLs with improved thermal properties.
Experimental analysis of thermal properties of AlGaAs/GaAs quantum cascade lasers
Semiconductor Lasers and Laser Dynamics V, 2012
We report on detailed investigation of thermal performance of AlGaAs/GaAs quantum cascade lasers (QCL) emitting at wavelength of 9.4 µm, with a particular emphasis on the influence of different mounting options and device geometries, which are compared in terms of their influence on the relative increase of the active region temperature. The spatially resolved thermoreflectance (TR) is used to register temperature distribution over the facet of pulse operated QCLs. The devices' thermal resistances are derived from experimental data. Thermal resistances of 15 µm devices are the highest among the investigated device widths. By combining the experimental and numerical results, an insight into the thermal management in QCLs is gained. The thermal design focuses on optimization of heat dissipation in the device, improving the thermal behavior of QCLs. This is essential in order to increase the maximal operation temperature to further progress the applications of QCLs.
Self-consistent thermal simulation of GaAs/Al0.45Ga0.55As quantum cascade lasers
Journal of Computational Electronics, 2012
This paper presents a self-consistent thermal model for quantum cascade lasers (QCLs) that takes into account the nonuniform heat generation distribution in the active region as well as the temperature dependences of the heat generation rate and thermal conductivity. The model extracts the heat generation rate from the electron-optical phonon scattering recorded during the ensemble Monte Carlo (EMC) simulation of electron transport in a single QCL stage at different temperatures. The extracted heat generation rate, in conjunction with temperature-dependent thermal conductivities, enables us to solve the nonlinear heat diffusion equation in a self-consistent manner. The model is used to investigate the cross-plane temperature distribution throughout a 9.4 µm infrared GaAs-based QCL. The nonlinear effects stemming from the temperature dependence of thermal conductivity and the heat generation rate are studied. Finally, the accuracy of using the equivalent uniform heat source with the total power obtained from experiments to model the thermal performance of QCLs is evaluated and discussed.
Thermal Modelling of Quantum Cascade Lasers
2009
One of the top priorities in the development of quantum cascade laser sources is the optimization of the heat transport dynamic. We review here our experimental studies on the thermal properties of state of art quantum cascade lasers operating both in the mid-IR and THz ranges. The experimental approach is based on the investigation of the band-to-band photoluminescence signals, collected during device continuous wave operation. We measured the lattice temperature profile on the device front facet and using these data as inputs, we extract the heat dissipation patterns, the in-plane and the cross-plane active region thermal conductivities and the thermal boundary resistance for quantum cascade lasers based on different material systems.
Photonics
In this paper, we report on the experimental investigation of the thermal performance of lattice matched AlInAs/InGaAs/InP quantum cascade lasers. Investigated designs include double trench, single mesa, and buried heterostructures, which were grown by combined Molecular Beam Epitaxy (MBE) and Metal Organic Vapor Phase Epitaxy (MOVPE) techniques. The thermal characteristics of lasers are investigated by Charge-Coupled Device CCD thermoreflectance. This method allows for the fast and accurate registration of high-resolution temperature maps of the whole device. We observe different heat dissipation mechanisms for investigated geometries of Quantum Cascade Lasers (QCLs). From the thermal point of view, the preferred design is the buried heterostructure. The buried heterostructures structure and epi-layer down mounting help dissipate the heat generated from active core of the QCL. The experimental results are in very good agreement with theoretical predictions of heat dissipation in various device constructions.
Impact of heat dissipation on quantum cascade laser performance
Journal of Applied Physics, 2013
We describe a simple and convenient method to analyze the impact of heating in a quantum-cascade laser on its basic performance characteristics. This method has only one fitting parameter, the thermal resistance of the laser, R th , while the other parameters can be directly measured in pulsed mode. Furthermore, the method can be applied even in the case when lasers do not reach continuouswave operation. The method was used to analyze a quantum-cascade laser emitting at k ¼ 10:6 lm and based on InGaAs-InAlAs material system, lattice-matched to InP. The thermal resistance of R th ¼ 10 K/W determined using the described method and the flat active region shape imply a vertical thermal conductivity value of j ? ¼ 0:53 W=m Á K for the lattice-matched InGaAs-InAlAs active region, which agrees well with literature values. V C 2013 American Institute of Physics.
Thermal effects in InGaAs/AlAsSb quantum-cascade lasers
IEE Proceedings - Optoelectronics, 2006
A quantum cascade laser (QCL) thermal model is presented. Based upon a finite-difference approach, the model is used in conjunction with a self-consistent carrier transport model to calculate the temperature distribution in a near-infrared InGaAs/AlAsSb QCL. The presented model is used to investigate the effects of driving conditions and device geometries on the active region temperature, which has a major influence on the device performance. A buried heterostructure (BH) combined with epilayer-down bonding is found to offer the best performance compared to alternative structures and has thermal times constants up to eight times smaller. The presented model provides a valuable tool for understanding the thermal dynamics inside a QCL and will help to improve operating temperatures.
Components and Packaging for Laser Systems II, 2016
There are a number of military and commercial applications for high-power laser systems in the mid-to-long-infrared wavelength range. By virtue of their demonstrated watt-level performance and wavelength diversity, quantum cascade laser (QCL) and amplifier devices are an excellent choice of emitter for those applications. To realize the power levels of interest, beam combining of arrays of these emitters is required and as a result, array technology must be developed. With this in mind, packaging and thermal management strategies were developed to facilitate the demonstration of a monolithic QCL array operating under CW conditions. Thermal models were constructed and simulations performed to determine the effect of parameters such as array-element ridge width and pitch on gain region temperature rise. The results of the simulations were considered in determining an appropriate QCL array configuration. State-of-the-art micro-impingement cooling along with an electrical distribution scheme comprised of AlN multi-layer technology were integrated into the design. The design of the module allows for individual electrical addressability of the array elements, a method of phase control demonstrated previously for coherent beam combining of diode arrays, along with access to both front and rear facets. Hence, both laser and single-pass amplifier arrays can be accommodated. A module was realized containing a 5 mm cavity length monolithic QCL array comprised of 7 elements on 450 m pitch. An output power of 3.16 W was demonstrated under CW conditions at an emission wavelength of 9 m.
Influence of Operating Conditions on Quantum Cascade Laser Temperature
Journal of Electronic Materials, 2010
In this work, the influence of operating conditions on the temperature of a quantum cascade laser (QCL) was studied experimentally by means of thermoreflectance, a nondestructive optical modulation technique providing information on the temperature of the laser facet. The heat load in the devices was changed by changing the duty cycle at constant pulse repetition rate. The measured temperature increases under pulsed operation, allowing the thermal resistance to be determined.