Abstract
The generation of high frequency signals into the terahertz range is dominated by photonics-based systems pushing the development of ultra-broadband wireless communication links. Recently, photonic integrated circuits have been proposed to implement different photonic signal generation techniques offering different semiconductor laser structures. Here we present for the first time a dual wavelength source for optical heterodyning based on hybrid integration of active InP elements and thermo-optically tunable polymer waveguide structures. The chip integrates two external cavity lasers, each with an InP gain chip coupled to a polymer phase and Bragg gratings sections, combined with a Y-junction. Each laser has a wavelength tuning range over 20 nm, enabling the generation of signals from tenths of GHz up to several THz with MHz resolution. We demonstrate the generation of a 330-GHz free-running beat-note has a linewidth of few MHz ( â¼3 MHz).