Traveling wave electro-optically modulated coupled-cavity surface emitting lasers.

We present a design of a high speed electro-optically modulated coupled-cavity vertical-cavity surface emitting laser monolithically integrated in a traveling wave electrode structure (TW EOM CC-VCSEL). Such electrical configuration allows to overcome RC time constant limitations of a traditional lumped electrodes design. We use segmented transmission line to match the impedance of the whole structure to the 50 Omega electrical network. We use transmission matrix method to model the response of the device and reflections at the voltage source interface. The CC-VCSEL optical design is based on longitudinal mode switching induced by the electro-optic effect, which has been recently experimentally demonstrated. In the paper we present analysis of electrical equivalent circuits of passive and modulator sections. We optimize our structure with respect to the device physical dimensions, frequency response, microwave reflections and modulation efficiency. We propose two different designs that are theoretically able to reach modulation speeds limited only by carrier extraction time from the quantum wells of the modulator and at the same time having lower than -20 dB reflections to the voltage source. For 1.5 lambda long modulator cavity, carrier saturation velocity limits the bandwidth of proposed structures to approximate to 390 GHz.