Photonic integrated circuits for terahertz source generation

Abstract

The authors introduce four kinds of terahertz photonics components based on photonic integrated circuits (PICs). A PIC-based integrated optoelectronic synthesiser for THz communications is described, which can be tuned continuously over the range 0.254-2.723 THz using photomixing. A laterally-coupled dual-grating distributed feedback laser (DFB) diode integrated with an electroabsorption modulator is used to generate an 820 GHz beat signal. THz signal production is reported using a dual-wavelength DFB diode laser with a two-section phase-shifted sampled Bragg grating. Finally, a THz source at 640 GHz, based on a sampled grating distributed Bragg reflector semiconductor mode-locked laser diode, is reported offering superior reproducibility, controllability, and a wider operation range than other reported mode-locked THz laser diodes. Each of these sources is a monolithic construction emitting light at 1.5 µm. The light can be amplified in an erbium-doped fibre amplifier, delivered over silica optical fibre and used to generate THz radiation via a photodiode antenna or photoconductive antenna in a remote location.