This article presents the design, implementation and characterization of a Littman-Metcalf extended-cavity diode laser. The extended cavity is closed by a roof (retro-reflecting) prism. The wavelength tuning is based on a two degrees-of-freedom monolithic flexure-based mechanism. The linear stroke for cavity length tuning is minimized by optimizing the position of the prism's rotation axis. The wavelength tuning with narrowband emission line is demonstrated in the spectral range of 837 nm to 870 nm.

We present a method to produce a fast frequency swept laser emission from a monolithic mid-infrared laser. A commercially available Fabry–Pérot cavity quantum cascade laser (QCL) operating at a wavelength of 8.15 μm was electrically driven by a current pulse with a 10 μs duration and a slow front rising time of ∼2 μs. Due to the switching of the lasing emission from the vertical to the diagonal transition in the QCL and a strong quantum-confined Stark effect energy shift of the diagonal transition, the frequency of the emitted light was blue-shifting as the injection current continues to raise above the threshold. The temporal evolution of the laser spectrum was measured by a high-resolution step-scan Fourier transform infrared spectrometer. The blue-chirped emission was strongly influenced by the heatsink temperature due to the high thermal sensitivity of the threshold current and slope efficiency. By optimizing carefully the QCL operating temperature and the amplitude of the current pulse, we demonstrate a high-speed self-sweeping laser emission under room temperature operation conditions, reaching the spectral tuning range of ∼25 cm⁻¹ within 1.8 μs.

We present a pseudo-random-noise modulation, continuous-wave (PRN-cw) total backscatter lidar based on AlGaAs diode laser. The amplitude PRN modulation is introduced by AOM on the cw laser radiation. The detection makes use of a cooled PMT in photon-counting mode. The PRN waveform generator, the data acquisition system and the data processing are steered by the same PC computer. The connections from the laser to the beam-expander and from the telescope to PMT housing are made with optical fibers. Lidar signals of topographic targets, clouds, and the atmospheric return are presented.

Quantum optics largely relies on the fundamental concept that the diffraction and interference patterns of a multi-partite state are determined by its de Broglie wavelength. In this paper we show that this is still true for a mixed state with one sub-system being in a classical coherent state and one being in entangled state. We demonstrate the quantum-classical light discrimination using de Broglie wavelength for the states with all classical parameters being the same.