High dynamic range, heterogeneous, terahertz quantum cascade lasers featuring thermally-tunable frequency comb operation over a broad current range

Abstract

We report on the engineering of broadband quantum cascade lasers (QCLs) emitting at Terahertz (THz) frequencies, which exploit a heterogeneous active region scheme and have a current density dynamic range (Jdr) of 3.2, significantly larger than the state of the art, over a 1.3 THz bandwidth. We demonstrate that the devised broadband lasers operate as THz optical frequency comb synthesizers in continuous wave, with a maximum optical output power of 4 mW (0.73 mW in the comb regime). Measurement of the intermode beatnote map reveals a clear dispersion-compensated frequency comb regime extending over a continuous 106 mA current range (current density dynamic range of 1.24), significantly larger than the state of the art reported under similar geometries, with a corresponding emission bandwidth of 1.05 THz ans a stable and narrow (4.15 KHz) beatnote detected with a signal-to-noise ratio of 34 dB. Analysis of the electrical and thermal beatnote tuning reveals a current-tuning coefficient ranging between 5 MHz/mA and 2.1 MHz/mA and a temperature-tuning coefficient of -4 MHz/K. The ability to tune the THz QCL combs over their full dynamic range by temperature and current paves the way for their use as powerful spectroscopy tool that can provide broad frequency coverage combined with high precision spectral accuracy.

References in corpus (5)

• Octave-spanning semiconductor laser
• Coherent Frequency Combs produced by Self Frequency Modulation in Quantum Cascade Lasers
• Short pulse generation and mode control of broadband terahertz quantum cascade lasers
• Ultra-broadband quantum cascade laser operating from 1.88 to 3.82 THz
• Unveiling spectral purity and tunability of terahertz quantum cascade laser sources based on intra-cavity difference frequency generation

Cited by in corpus (8)

• Fully phase-stabilized quantum cascade laser frequency comb
• Ultrashort pulse generation from a graphene-coupled passively mode-locked terahertz laser
• On-chip mid-infrared and THz frequency combs for spectroscopy
• Engineering THz-frequency light generation, detection and manipulation through graphene
• Homogeneous quantum cascade lasers operating as Terahertz frequency combs over their entire operational regime
• Real-time multimode dynamics of terahertz quantum cascade lasers via intracavity self-detection: observation of self mode-locked population pulsations
• Chip-scale terahertz frequency combs through integrated intersubband polariton bleaching
• Photon-driven broadband emission and RF injection locking of THz quantum cascade laser frequency combs