Compact and reconfigurable fiber-based terahertz spectrometer at 1550 nm

Abstract

In this paper, we present a new compact and versatile spectrometer system operating at 1.55 μm for research and industrial application. The system is capable of testing solid, powder, thin film, gas, and liquid samples for material sensing and characterization applications. A high efficient system with bandwidth up to 1.2 THz is realized by using a fiber coupled terahertz chip packaging technology. The key components are the fiber-coupled THz transmitter and receiver modules, where the laser beam is directly coupled to the THz chip using optical fibers to provide stable and movable transmitter and receiver heads. The antennas are excited by 100 fs optical pulses at 1550 nm telecom wavelength and average power of 10mW. As femtosecond pulses are required on the antenna, the linear dispersion and nonlinear effect resulting from the propagation of the high power optical pulse along the fiber are taken into account and compensated using dispersion compensation fiber. A fast scan optical delay module is employed to realize real-time THz signal and spectrum measurement. The optical delay module also has a long delay scan unit to allow the user to adjust the distance between the transmitter and receiver heads by up to 1m to use the system for characterization of materials in different industrial applications.