Control of Optical Gain in the Active Region of Quantum Cascade Laser by Strong Perpendicular Magnetic Field

2005 ◽  
pp. 31-36
Author(s):  
J. Radovanović ◽  
V. Milanović ◽  
Z. Ikonić ◽  
D. Indjin
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Quantum Cascade Laser ◽  
Optical Gain ◽  
Perpendicular Magnetic Field ◽  
Quantum Cascade

scholarly journals Quantum cascade laser: Applications in chemical detection and environmental monitoring

2009 ◽  
Vol 24 (2) ◽  
pp. 75-81 ◽  
Author(s):  
Jelena Radovanovic ◽  
Vitomir Milanovic
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Quantum Cascade Laser ◽  
Optical Gain ◽  
Ambient Air ◽  
Landau Levels ◽  
Fine Tuning ◽  
Structural Parameter ◽  
Laser Applications ◽  
Quantum Cascade

In this paper we consider the structural parameter optimization of the active region of a GaAs-based quantum cascade laser in order to maximize the optical gain of the laser at the characteristic wavelengths, which are best suited for detection of pollutant gasses, such as SO2, HNO3, CH4, and NH3, in the ambient air by means of direct absorption. The procedure relies on applying elaborate tools for global optimization, such as the genetic algorithm. One of the important goals is to extend the applicability of a single active region design to the detection of several compounds absorbing at close wave-lengths, and this is achieved by introducing a strong external magnetic field perpendicularly to the epitaxial layers. The field causes two-dimensional continuous energy subbands to split into the series of discrete Landau levels. Since the arrangement of Landau levels depends strongly on the magnitude of the magnetic field, this enables one to control the population inversion in the active region, and hence the optical gain. Furthermore, strong effects of band non-parabolicity result in subtle changes of the lasing wavelength at magnetic fields which maximize the gain, thus providing a path for fine-tuning of the output radiation properties and changing the target compound for detection. The numerical results are presented for quantum cascade laser structures designed to emit at specified wavelengths in the mid-infrared part of the spectrum.

Control of Optical Gain in the Active Region of Quantum Cascade Laser by Strong Perpendicular Magnetic Field

2005 ◽  
Vol 494 ◽  
pp. 31-36 ◽  
Author(s):  
J. Radovanović ◽  
V. Milanović ◽  
Z. Ikonić ◽  
D. Indjin
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Quantum Cascade Laser ◽  
Phonon Scattering ◽  
Optical Gain ◽  
Landau Levels ◽  
Quantum Cascade ◽  
Emit Radiation ◽  
Electron Dispersion ◽  
The Magnetic Field

The optical gain in the active region of quantum cascade laser in an external magnetic field is analyzed. When the magnetic field is applied in the direction perpendicular to the plane of the layers, electron dispersion is broken into series of discrete Landau levels. This additional confinement strongly modifies the lifetime of electrons in the upper state of the laser transition, which is controlled by electron-phonon scattering. Landau levels are magnetically tuneable and, depending on their configuration, phonon emission is either inhibited or resonantly enhanced. This translates into a strong modulation of the population inversion, and consequently of the optical gain by varying the magnetic field. Numerical results are presented for a structure previously considered by Smirnov et al. [Phys. Rev B 66 (2002) 125317] which is designed to emit radiation at λ~11.4µm, with the magnetic field varied in the range 10-60T. The effects of band nonparabolicity are taken into account in this model.

scholarly journals Electron-phonon relaxation rates and optical gain in a quantum cascade laser in a magnetic field

2005 ◽  
Vol 97 (10) ◽  
pp. 103109 ◽  
Author(s):  
J. Radovanović ◽  
V. Milanović ◽  
Z. Ikonić ◽  
D. Indjin ◽  
P. Harrison
Keyword(s):  
Magnetic Field ◽  
Quantum Cascade Laser ◽  
Optical Gain ◽  
Relaxation Rates ◽  
Quantum Cascade

Recent Results on the Road to a SiGe Quantum Cascade Laser

2004 ◽  
Vol 832 ◽  
Author(s):  
Alex Borak ◽  
Soichiro Tsujino ◽  
Claudiu Falub ◽  
Maxi Scheinert ◽  
Laurent Diehl ◽  
...  
Keyword(s):  
Active Region ◽  
Quantum Cascade Laser ◽  
Optical Gain ◽  
Interface Roughness ◽  
Free Carrier Absorption ◽  
Quantum Cascade ◽  
The Road ◽  
Detailed Structural Analysis ◽  
On The Road ◽  
Growth Quality

ABSTRACTThe primary challenges in implementing a Si based quantum cascade laser are discussed. Intersubband absorption measurements were carried out on a series of modulation doped multiquantum well structures. The spectra were compared to the predictions of a 6 band k.p model, which confirmed the excellent accuracy of the model, and its ability to predict the bandstructures of more complicated cascade structures. A detailed structural analysis demonstrated excellent growth quality, with an interface roughness of < 0.4 nm. Electroluminescence measurements on cascade structures with doped contacts, processed as finger structures and waveguides of various sizes, enabled a quantitative analysis of the active region performance. The upper state lifetime τnr was ∼ 100 fs, leading to a total active region optical gain of ∼ 2 cm−1, a factor of ∼ 10 lower than the estimated total losses due to free carrier absorption. The total emitted power and the linewidth of the intersubband emission saturate above ∼ 6.5 kA/cm2, probably due to misalignment of the injector levels at high biases. The effect of leak currents and interspersed light hole states on the intersubband emission are considered.

scholarly journals A THz quantum cascade detector in a strong perpendicular magnetic field

2006 ◽  
Vol 21 (12) ◽  
pp. 1743-1746 ◽  
Author(s):  
Giacomo Scalari ◽  
Marcel Graf ◽  
Daniel Hofstetter ◽  
Jérôme Faist ◽  
Harvey Beere ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Perpendicular Magnetic Field ◽  
Quantum Cascade

Quantum cascade lasers in magnetic field: An active region model

2005 ◽  
Vol 242 (9) ◽  
pp. 1812-1816 ◽  
Author(s):  
I. Savić ◽  
V. Milanović ◽  
D. Indjin ◽  
Z. Ikonić ◽  
V. D. Jovanović ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Quantum Cascade Lasers ◽  
Quantum Cascade ◽  
Region Model ◽  
Active Region Model ◽  
Cascade Lasers
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