In this work we present performance characteristics of metalorganic vapor-plase epitaxy grown GaInNAs and InGaAs quantum-well (QW) vertical-cavity lasers (VCLs) for 1.3-μm applications. The InGaAs VCLs emit in a wavelength range from 1200 to somewhat above 1260 nm, while the GaInNAs VCLs operate from 1264 to 1303 nm. The InGaAs VCLs are based on highly strained InGaAs double QWs, with photoluminescence (PL) maximum around 1190 nm, and extensive negative gain-cavity detuning. As a consequence, these devices are strongly temperature sensitive and the minimum threshold current is found at very high temperature (~90-100°C). Both kind of VCLs work continuous-wave well above 100°C, and while the InGaAs VCLs reach slightly higher light output power, they show significantly larger threshold currents. In addition, the large device detuning also has profound effects on the high-frequency response. Nevertheless, for a 1260-nm device, 10 Gb/s transmission is demonstrated in a back-to-back configuration. We also show that by further optimization of the InGaAs QWs the PL peak wavelength can be extended to at least 1240 nm. The incorporation of such QWs in the present VCL structure should considerably improve the device performance, resulting in higher light output power, lower threshold current, and reduced temperature sensitivity with a shift of the minimum threshold current towards room temperature, thus approaching standard VCL tuning.
We compare GaInNAs and highly strained InGaAs quantum-wells (QWs) for applications in metal-organic vapor-phase epitaxy (MOVPE)-grown GaAs-based 1300-nm vertical-cavity lasers (VCLs). While the peak wavelength of InGaAs QWs can be extended by a small fraction of N, the luminescence efficiency degrades strongly with wavelength. On the other hand, using highly strained InGaAs QWs in combination with a large VCL detuning it is also possible to push the emission wavelength towards 1.3 μm. The optimized MOVPE growth conditions for such QW and VCL structures are discussed in some detail. It is noted that GaInNAs and InGaAs QWs preferably are grown at low temperature, but with quite different V/III ratios and growth rates. We also point out the importance of reduced doping concentration and growth temperature of the n-doped bottom DBR to minimize optical loss and for compatibility with GaInNAs QWs. InGaAs VCLs with emission wavelength beyond 1260 nm is demonstrated. This includes mW-range output power, mA-range threshold current and 10 Gb/s data transmission.
We present a study of barrier height effects on the high-temperature performance of 1.3 micron strained layer InGaAsP/InP quantum well lasers. Broad-area Fabry-Perot lasers were fabricated and their light-current characteristics were measured at temperatures between 20 degrees C and 80 degrees C. Based on our experimental results we analyze the effect of the barrier bandgap using the commercial laser simulation software LASTIP. The simulator calculates all relevant physical mechanisms, including their dependence on temperature and local carrier density, self-consistently. The strained quantum-well optical gain computation is based on the 4 x 4 kp method considering valence-band mixing effects. A drift-diffusion model including thermionic emission at hetero-interfaces is used for the calculation of the carrier transport. Careful adjustments of material parameters, in agreement with data reported in the literature, are performed in order to reproduce the measurements. Lowering the barrier height in the active region leads to an improved performance of our laser with respect to threshold current and slope efficiency. An optimum barrier bandgap range of 1.21 - 1.24 eV is identified for our laser. This is partially attributed to the non-uniform carrier-distribution across the quantum-wells.