Electro-optical intersubband applications an modulators at telecommunication wavelengths based on GaN/AlN quantum wells

We report the demonstration of intersubband modulators operating at telecommunication wavelengths at room temperature based on GaN/AlN quantum wells. We first investigate electro-optical modulators making use of electron tunneling in coupled quantum wells. Electro-absorption modulation with opposite sign induced by the electron tunneling between the reservoir and active quantum wells is observed at λ = 1.3 - 1.6 μm and λ = 2.2 μm. We show that by reducing the mesa size down to 15 × 15 μm 2 , optical modulation bandwidth as large as 3 GHz can be obtained. We then investigate waveguide intersubband modulators on the depletion of the ground electronic state of a 3 quantum well active region. Modulation depths as large as 14 dB in the wavelength range of 1.2-1.6 μm are obtained under -9 V/+7 V voltage swing.