Data associated with 'Quasi-continuous frequency tunable terahertz quantum cascade lasers with coupled cavity and integrated photonic lattice'

This dataset contains experimental data presented in the paper titled 'Quasi-continuous frequency tunable terahertz quantum cascade lasers with coupled cavity and integrated photonic lattice'. Quasi-continuous tuning of the emission frequency is demonstrated from a coupled cavity (CC) terahertz (THz) frequency quantum cascade laser (QCL). Such CC lasers comprise of a lasing and a tuning cavity, which are physically separated but optically coupled through a narrow air gap. The lasing and the tuning cavities are operated above and below the lasing threshold current, respectively. The emission frequency from such CC lasers is determined by the Vernier resonance of longitudinal modes in the lasing and the tuning cavities, respectively. Furthermore, emission frequency can be tuned by applying suitable index perturbation to the tuning cavity. The spectral coverage from such THz CC QCLs have been increased by reducing the repetition frequency of the Vernier resonance, and by increasing the ratio of the free spectral ranges of the two cavities. Additionally, wide electrical heating pulses were supplied at the tuning cavity and thermal conduction through the monolithic substrate was exploited to introduce a thermal index perturbation to the lasing cavity itself, thereby enabling a continuous tuning of the CC modes. Single mode emission and discrete frequency tuning over a bandwidth of 100 GHz, and a quasi-continuous frequency tuning of 7 GHz at 2.25 THz is realised. Furthermore, a π-phase shifted photonic lattice is introduced in the laser cavity to obtain a continuous spectral coverage of 3 GHz, without any degradation of output power.