Thermal Equivalent Circuit Model for Coupled-Cavity Surface-Emitting Lasers (original) (raw)
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A comprehensive circuit-level model of vertical-cavity surface-emitting lasers
Journal of Lightwave Technology, 1999
The increasing interest in vertical-cavity surfaceemitting lasers (VCSEL's) requires the corresponding development of circuit-level VCSEL models for use in the design and simulation of optoelectronic applications. Unfortunately, existing models lack either the computational efficiency or the comprehensiveness warranted by circuit-level simulation. Thus, in this paper we present a comprehensive circuit-level model that accounts for the thermal and spatial dependence of a VCSEL's behavior. The model is based on multimode rate equations and empirical expressions for the thermal dependence of the activelayer gain and carrier leakage, thereby facilitating the simulation of VCSEL's in the context of an optoelectronic system. To confirm that our model is valid, we present sample simulations that demonstrate its ability to replicate typical dc, small-signal, and transient operation, including temperature-dependent lightcurrent (LI) curves and modulation responses, multimode behavior, and diffusive turn-off transients. Furthermore, we verify our model against experimental data from four devices reported in the literature. As the results will show, we obtained excellent agreement between simulation and experiment.
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.
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.
Rate-equation model for coupled-cavity surface-emitting lasers
IEEE Journal of Quantum Electronics, 2000
ABSTRACT We present a detailed theoretical study of a vertical-cavity surface-emitting laser (VCSEL) with two optically coupled, active cavities. The study is based on a rate-equation model written for carriers and photons under steady-state conditions. The model allows one to determine all the relevant parameters-carrier densities, gains, and output powers-starting from two input parameters: the injection currents in each cavity. The system of equations is solved for different operating regimes of the device and the results provided by the model are shown to be in very good qualitative and quantitative agreement with the experimental data.
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.
A simple rate-equation-based thermal VCSEL model
1999
Motivated by the potentially large number of devices and simulations involved in optoelectronic system design, and the associated need for compact optoelectronic device models, we present a simple thermal model of vertical-cavity surface-emitting laser (VCSEL) light-current (LI) characteristics based on the laser rate equations and a thermal offset current. The model was implemented in conventional SPICE-like circuit simulators, including HSPICE, and used to simulate key features of VCSEL LI curves, namely, thermally dependent threshold current and output-power roll-over for a range of ambient temperatures. The use of the rate equations also allows simulation in other non-dc operating regimes. Our results compare favorably to experimental data from three devices reported in the literature.
Rate-equation-based VCSEL thermal model and simulation
Journal of Zhejiang University SCIENCE A, 2006
In this paper, we present a simple thermal model of Vertical-Cavity Surface-Emitting Laser (VCSEL) light-current (LI) characteristics based on the rate-equation. The model can be implemented in conventional SPICE-like circuit simulators, including HSPICE, and be used to simulate the key features of VCSEL. The results compare favorably with experimental data from a device reported in the literature. The simple empirical model is especially suitable for Computer Aided Design (CAD), and greatly simplifies the design of optical communication systems.
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
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.
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.