QCL-based frequency metrology from the mid-infrared to the THz range: a review

Abstract

Quantum cascade lasers (QCLs) are becoming a key tool for plenty of applications, from the mid-infrared (mid-IR) to the THz range. Progress in related areas, such as the development of ultra-low-loss crystalline microresonators, optical frequency standards, and optical fiber networks for time and frequency dissemination, is paving the way for unprecedented applications in many fields. For most demanding applications, a thorough control of QCLs emission must be achieved. In the last few years, QCLs unique spectral features have been unveiled, while multifrequency QCLs have been demonstrated. Ultra-narrow frequency linewidths are necessary for metrological applications, ranging from cold molecules interaction and ultra-high sensitivity spectroscopy to infrared-THz metrology. A review of the present status of research in this field is presented, with a view of perspectives and future applications.

References in corpus (7)

• Octave-spanning semiconductor laser
• An octave spanning mid-infrared frequency comb generated in a silicon nanophotonic wire waveguide
• Stability of the proton-to-electron mass ratio
• Quantum cascade laser frequency stabilisation at the sub-Hz level
• A widely tunable 10-$\mu$m quantum cascade laser phase-locked to a state-of-the-art mid-infrared reference for precision molecular spectroscopy
• A quantum cascade laser-based mid-IR frequency metrology system with ultra-narrow linewidth and $1\times 10^{-13}$-level frequency instability
• Laser spectroscopy of cold molecules

Cited by in corpus (7)

• Retrieval of phase relation and emission profile of quantum cascade laser frequency combs
• Homogeneous quantum cascade lasers operating as Terahertz frequency combs over their entire operational regime
• Direct observation of terahertz frequency comb generationin difference-frequency quantum cascade lasers
• Characterization of noise regimes in Mid-IR free-space optical communication based on quantum cascade lasers
• Highly coherent phase-lock of an 8.1 $\mu$m quantum cascade laser to a turn-key mid-IR frequency comb
• Ultra-sensitive heterodyne detection at room temperature in the atmospheric windows
• Phase analysis and full phase control of chip-scale infrared frequency combs