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Université de Neuchâtel

Continuous-wave distributed-feedback quantum-cascade lasers on a Peltier cooler

Aellen, Thierry ; Blaser, Stéphane ; Beck, Mattias ; Hofstetter, Daniel ; Faist, Jérôme ; Gini Emilio

In: Applied Physics Letters, 2003, vol. 83, p. 1929-1931

Continuous-wave operation of λ~9 µm distributed-feedback quantum-cascade lasers is reported up to a temperature of 260 K. Single-frequency emission with a side mode suppression ratio of ≥27 dB and with a tuning range of 5 cm–1 between 200 and 245 K (a tunability of –0.078 cm–1/K and –0.764 cm–1/W) is obtained for the junction-down mounted...

Université de Neuchâtel

Continuous-wave operation of far-infrared quantum cascade lasers

Ajili, Lassaad ; Scalari, Giacomo ; Hofstetter, Daniel ; Beck, Mattias ; Faist, Jérôme ; Beere, Harvey ; Davies, Giles ; Linfield, Edmund ; Ritchie, David

In: Electronics Letters, 2002, vol. 38, no. 25, p. 1675-1676

Continuous-wave operation of a terahertz quantum cascade laser is reported. Optical output powers ranging from 410 µW at 10 K to 124 µW at 35 K, at an emission wavelength of 66 µm are obtained.

Université de Neuchâtel

Near infrared absorption and room temperature photovoltaic response in AlN/GaN superlattices grown by metal-organic vapor-phase epitaxy

Baumann, Esther ; Giorgetta, Fabrizio R. ; Hofstetter, Daniel ; Golka, Sebastian ; Schrenk, W. ; Strasser, Gottfried ; Kirste, Lutz

In: Applied Physics Letters, 2006, vol. 89, no. 041106, p. 1-3

We report on intersubband absorption of near infrared radiation in AlN/GaN superlattice structures grown by metal-organic vapor-phase epitaxy. A good correlation between well thickness and absorption peak energy was obtained. One sample shows a photovoltaic signal which overlaps well with the corresponding absorption curve at around 1.5 µm (830 meV), a common wavelength in optical fiber...

Université de Neuchâtel

Electrically adjustable intersubband absorption of a GaN/AlN superlattice grown on a transistorlike structure

Baumann, Esther ; Giorgetta, Fabrizio R. ; Hofstetter, Daniel ; Leconte, Sylvain ; Guillot, Fabien ; Bellet-Amalric, Edith ; Monroy, Eva

In: Applied Physics Letters, 2006, vol. 89, no. 101121, p. 1-3

The authors report on electromodulated intersubband (ISB) absorption experiments on AlN/GaN superlattices (SLs) grown on a transistorlike structure. A sample containing five SL periods shows two distinct absorption peaks related to ISB transitions in the SL and in the two dimensional electron gas located at the interface of the lowest SL barrier and the underlying GaN buffer. The ratio of those...

Université de Neuchâtel

Tunneling effects and intersubband absorption in AlN/GaN superlattices

Baumann, Esther ; Giorgetta, Fabrizio R. ; Hofstetter, Daniel ; Wu, H. ; Schaff, W. J. ; Eastman, L. F. ; Kirste, Lutz

In: Applied Physics Letters, 2006, vol. 86, no. 032110, p. 1-3

We report on intersubband absorption and photovoltage measurements on regular GaN/AlN-based superlattice structures. For barrier thicknesses larger than about 25 Å, the optical intersubband absorption peaks at a considerably smaller energy than the photovoltage spectrum. A simple model taking into account the oscillator strength of the involved transitions and the corresponding tunneling...

Université de Neuchâtel

Intersubband photoconductivity at 1.6 µm using a strain-compensated AlN/GaN superlattice

Baumann, Esther ; Giorgetta, Fabrizio R. ; Hofstetter, Daniel ; Lu, H. ; Chen, X. ; Schaff, William J. ; Eastman, L. F. ; Golka, Sebastian ; Schrenk, W. ; Strasser, Gottfried

In: Applied Physics Letters, 2005, vol. 87, no. 191102, p. 1-3

We report on intersubband absorption, photovoltaic, and photoconductive detection of near-infrared radiation in regular AlN/GaN superlattice structures. Photoconductive detection was achieved up to temperatures of 120 K. Simulation of the transition energies using a self-consistent Schrödinger-Poisson equation solver for our specific well width is in good agreement with the measurements. For a...

Université de Neuchâtel

Resonant tunnelling and intersubband absorption in AlN - GaN superlattices

Baumann, Esther ; Giorgetta, Fabrizio R. ; Hofstetter, Daniel ; Wu, Hong ; Schaff, William J. ; Eastman, Lester F. ; Kirste, Lutz

In: Physica status solidi (c), 2005, vol. 2, no. 3, p. 1014-1018

We report on intersubband absorption and photovoltage measurements on regular GaN/AlN-based superlattice structures at 1.55 µm. For high barriers, the photovoltage peaks at a higher energy than the absorbance spectrum due to the decrease of the tunnelling probability. The observed photovoltage is thus the macroscopic manifestation that the 2-dimensional electron gas at the top of the...

Université de Neuchâtel

GaN/AlN electro-optical modulator prototype at telecommunication wavelengths

Baumann, Esther ; Giorgetta, Fabrizio R. ; Hofstetter, Daniel ; Guillot, Fabien ; Leconte, Sylvain ; Bellet-Amalric, Edith ; Monroy, Eva

In: Physica status solidi (c), 2007, vol. 4, no. 5, p. 1621-1624

We report on a prototype electro-optical modulator at telecommunication wavelength based on intersubband (ISB) transitions in a short-period GaN/AlN superlattice (SL). The device has a vertical architecture resembling a nitride-based high-electron mobility transistor, whose barrier layer has been replaced by a 5 period SL. By applying an electrical field, we were able to influence the...

Université de Neuchâtel

Continuous Wave Operation of a Mid-Infrared Semiconductor Laser at Room Temperature

Beck, Mattias ; Hofstetter, Daniel ; Aellen, Thierry ; Faist, Jérôme ; Oesterle, Ursula ; Ilegems, Marc ; Gini, Emilio ; Melchior, Hans

In: Science, 2002, vol. 295, no. 5553, p. 301-305

Continuous wave operation of quantum cascade lasers is reported up to a temperature of 312 kelvin. The devices were fabricated as buried heterostructure lasers with high-reflection coatings on both laser facets, resulting in continuous wave operation with optical output power ranging from 17 milliwatts at 292 kelvin to 3 milliwatts at 312 kelvin, at an emission wavelength of 9.1 micrometers. The...

Université de Neuchâtel

Continuous wave operation of quantum cascade lasers

Beck, Mattias ; Hofstetter, Daniel ; Aellen, Thierry ; Blaser, Stéphane ; Faist, Jérôme ; Oesterle, Ursula ; Gini Emilio

In: Journal of Crystal Growth, 2003, vol. 251, no. 1-4, p. 697-700

Continuous wave (CW) operation of quantum cascade lasers is reported up to temperatures of 312 K. The devices were fabricated as buried heterostructure lasers and episide-down mounted for improved heat dissipation. Fabry–Perot lasers emitted 17 mW of continuous optical power at 292 K and still 3 mW at 311 K at λ=9.12 μm. Distributed feedback quantum cascade lasers showed CW single-mode...