Université de Neuchâtel

Frequency Ageing and Noise Evolution in a Distributed Feedback Quantum Cascade Laser Measured Over a Two-Month Period

Schilt, Stéphane ; Tombez, Lionel ; Tardy, Camille ; Bismuto, Alfredo ; Blaser, Stéphane ; Maulini, Richard ; Terazzi, Romain ; Rochat, Michel ; Südmeyer, Thomas

In: IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS, 2015, vol. 21, no. 6, p. 1-6

We report on the evaluation of the frequency stability of a distributed feedback quantum cascade laser (QCL) at 8 µm that was continuously monitored over a 2-month period using a spectroscopic setup. The QCL was operated in continuous wave mode at room temperature (21.4 °C). It was driven by a home-made low-noise controller at a nominal current of ∼600 mA located in the middle of its...

Université de Neuchâtel

An experimental study of noise in midinfrared quantum cascade lasers of different designs

Schilt, Stéphane ; Tombez, Lionel ; Tardy, Camille ; Bismuto, Alfredo ; Blaser, Stéphane ; Maulini, Richard ; Terazzi, Romain ; Rochat, Michel ; Südmeyer, Thomas

In: Applied Physics B: Lasers and optics, 2015, vol. 119, no. 1, p. 189-201

We present an experimental study of noise in mid-infrared quantum cascade lasers (QCLs) of differ-ent designs. By quantifying the high degree of correlation occurring between fluctuations of the optical frequency and voltage between the QCL terminals, we show that electrical noise is a powerful and simple mean to study noise in QCLs. Based on this outcome, we investigated the electrical noise in...

Université de Neuchâtel

Chemical sensing with pulsed QC-DFB lasers operating at 15.6 μm

Kosterev, A. A. ; Curl, R. F. ; Tittel, F. K. ; Rochat, Michel ; Beck, Mattias ; Hofstetter, Daniel ; Faist, Jérôme

In: Applied Physics B: Lasers and Optics, 2002, vol. 75, no. 2-3, p. 351-357

Pulsed thermoelectrically cooled QC-DFB lasers operating at 15.6 μm were characterized for spectroscopic gas sensing applications. A new method for wavelength scanning based on repetition rate modulation was developed. A non-wavelength-selective pyroelectric detector was incorporated in the sensor configuration giving the advantage of room-temperature operation and low cost. Absorption lines of...

Université de Neuchâtel

Bound-to-continuum and two-phonon resonance, quantum-cascade lasers for high duty cycle, high-temperature operation

Faist, Jérôme ; Hofstetter, Daniel ; Beck, Mattias ; Aellen, Thierry ; Rochat, Michel ; Blaser, Stéphane

In: Journal of Quantum Electronics (IEEE), 2002, vol. 38, no. 6, p. 533-546

Recent advances in quantum-cascade (QC) laser active-region design are reviewed. Based on a rate equation model of the active region, we show why new gain regions. based on a two-phonon resonance or a bound-to-continuum transition exhibit significantly better performance than the traditional design based on a three-quantum-well active region. Threshold current densities as low as 3...

Université de Neuchâtel

Long-wavelength (λ ≈ 16 µm), room-temperature, single-frequency quantum-cascade lasers based on a bound-to-continuum transition

Rochat, Michel ; Hofstetter, Daniel ; Beck, Mattias ; Faist, Jérôme

In: Applied Physics Letters, 2001, vol. 79, p. 4271-4273

Room-temperature operation of long-wavelength, Fabry–Perot and single-mode quantum-cascade lasers at λ ≈ 16 µm is reported. Multimode emission with pulsed peak power up to 400 mW at –40 °C and 220 mW at 30 °C is demonstrated. Single-mode emission up to 60 mW peak power has been achieved at 30 °C.

Université de Neuchâtel

Terahertz intersubband emission in strong magnetic fields

Blaser, Stéphane ; Rochat, Michel ; Beck, Mattias ; Hofstetter, Daniel ; Faist, Jérôme

In: Applied Physics Letters, 2002, vol. 81, p. 67-69

Electroluminescence in quantum-cascade structures based on vertical transitions is studied in a strong perpendicular magnetic field in the limit in which the cyclotron energy is larger than the intersubband transition energy. Cyclotron emission and a luminescence intensity enhancement up to a factor of 6 is observed in GaAs/AlGaAs and InGaAs/InAlAs vertical transition-based quantum-cascade...