Near-Full Current Dynamic Range THz Quantum Cascade Laser Frequency Comb

The present study proposes a terahertz quantum cascade laser frequency comb (THz QCL FC) with a semi-insulated surface plasma waveguide characterized by a low threshold current density, high power and a wide current dynamic range. The gain dispersion value and the nonlinear susceptibility were optimized based on the combination of a hybrid bound-to-continuum active region with a semi-insulated surface plasmon waveguide. Without any extra dispersion compensator, stable frequency comb operation within a current dynamic range of more than 97% of the total was revealed by the intermode beat note map. Additionally, a total comb spectral emission of about 300 GHz centered around 4.6 THz was achieved for a 3 mm long and 150 mu m wide device. At 10 K, a maximum output power of 22 mW was obtained with an ultra-low threshold current density of 64.4 A center dot cm(-2).

Automated summary

The present study proposes a terahertz quantum cascade laser frequency comb (THz QCL FC) with a semi-insulated surface plasma waveguide. It exhibits a low threshold current density, high power, and a wide current dynamic range. The optimized gain dispersion value and nonlinear susceptibility are achieved through a hybrid bound-to-continuum active region with a semi-insulated surface plasmon waveguide. The device shows stable frequency comb operation within a current dynamic range of over 97%, without the need for extra dispersion compensator. A total comb spectral emission of about 300 GHz centered around 4.6 THz is achieved for the device with a length of 3 mm and width of 150 μm. At 10 K, it demonstrates a maximum output power of 22 mW with an ultra-low threshold current density of 64.4 A·cm-2.