Two-section InGaN multiple-quantum-well laser diode with integrated electroabsorption modulator

Abstract

$Q$ -switching is demonstrated in a two-section InGaN multiple-quantum-well (MQW) laser diode consisting of an electroabsorption modulator and amplifier (gain) section. The modulator and gain sections are optically coupled and share the same InGaN MQW active region, but they are electrically separated by a narrow dry-etched trench. Applying a reverse bias voltage to the modulator section controls the absorption in the modulator portion of the device by compensating the piezoelectric field in the InGaN quantum wells. Changes in the absorption coefficient as large as $\text{5000\hspace{0.17em}}{\mathrm{cm}}^{\text{−1}}$ were realized with a moderate reverse bias of 7.2 V. By forward biasing, the amplifier section at a constant current of 225 mA and by controlling the reverse bias modulator voltage, the output power of the two-section laser diode could be switched between $\text{<0.5\hspace{0.17em}}\mathrm{mW}$ (off state) and more than 3 mW (on state) with a laser emission wavelength near 401 nm.