We reduce the epitaxial design complexity of our conventional single-cavity oxide-aperture vertical-cavity surfaceemitting lasers (VCSELs) to reduce manufacturing costs while still meeting our internal 980 nanometer VCSEL performance goals via simplicity-in-design principles. We achieve maximum static single-mode optical output powers exceeding 4 milliwatts with small-signal modulation bandwidths exceeding 30 gigahertz at an ambient temperature of about 25 degrees Celsius for VCSELs with an oxide-aperture diameter of about 4 micrometers. Neighbor VCSELs with oxide-aperture diameters above 15 micrometers have maximum room temperature multiple-mode optical output powers of about 20 milliwatts with small-signal modulation bandwidths exceeding 20 gigahertz. The performance of our conventional oxide-confined 980 nanometer simplicity VCSELs exceeds the performance of our previously-reported and more complex 980 nanometer VCSEL epitaxial designs where we previously achieved maximum small-signal modulation bandwidths of about 26 gigahertz with oxide-aperture diameters of about 4 to 6 micrometers.
We present experimental results showing alternating lasing and non-lasing regions for the short-wavelength longitudinal mode in a GaAs-based 850 nm coupled-cavity vertical-cavity surface-emitting laser (CC-VCSEL). These regions are situated between the laser threshold and roll-off for this mode. The analyzed structure consists of two identical AlGaAs cavities with GaAs quantum wells, separated with 11.5 pairs of middle DBR. The current apertures are realized by ion-implantation for the top cavity and selective oxidation for the bottom cavity. We then perform fully-vectorial three-dimensional cold-cavity optical simulations to theoretically investigate optical density radial and on-optical-axis profiles of the first order transverse modes corresponding to the two longitudinal modes. We show that the short-wavelength fundamental mode λS-LP01 is subject to periodic changes of its optical field distribution when changing the oxide aperture radius, which can lead to weaker resonance of the short-wavelength LP01 mode within the coupled cavity structure.
In the talk we show the process of modeling complete physical properties of VCSELs and we present a step-by-step development of its complete multi-physics model, gradually improving its accuracy. Then we introduce high contrast gratings to the VCSEL design, which strongly complicates its optical modeling, making the comprehensive multi-physics VCSEL simulation a challenging task. We show, however, that a proper choice of a self-consistent simulation algorithm can still make such a simulation a feasible one, which is necessary for an efficient optimization of the laser prior to its costly manufacturing.
A self-consistent model of a GaAs-based 850 nm coupled-cavity vertical-cavity surface-emitting diode laser is presented. The analyzed laser consists of two identical AlGaAs cavities with GaAs quantum wells, separated with 10 pairs of middle DBR. The current apertures are realized by ion-implantation for the top cavity and selective oxidation for the bottom. To accurately simulate the physical phenomena present in the CW regime of the analyzed device, we use a multi-physical model, which comprises self-consistent Finite Element Method (FEM) thermo-electrical model. The numerical parameters have been found by the calibration based on experimental results. We have analyzed and shown the influence of the driving voltages on the temperature distribution within the analyzed structure and current densities in both cavities.
Via experimental results supported by numerical modeling we report the energy-efficiency, bit rate, and modal properties of GaAs-based 980 nm vertical cavity surface emitting lasers (VCSELs). Using our newly established Principles for the design and operation of energy-efficient VCSELs as reported in the Invited paper by Moser et al. (SPIE 9001-02 )  along with our high bit rate 980 nm VCSEL epitaxial designs that include a relatively large etalonto- quantum well gain-peak wavelength detuning of about 15 nm we demonstrate record error-free (bit error ratio below 10-12) data transmission performance of 38, 40, and 42 Gbit/s at 85, 75, and 25°C, respectively. At 38 Gbit/s in a back-toback test configuration from 45 to 85°C we demonstrate a record low and highly stable dissipated energy of only ~179 to 177 fJ per transmitted bit. We conclude that our 980 nm VCSELs are especially well suited for very-short-reach and ultra-short-reach optical interconnects where the data transmission distances are about 1 m or less, and about 10 mm or less, respectively.