Growth of a periodic InP-based heteroepitaxial structure for a quantum cascade laser

The route to grow InP-based heteroepitaxial structure for quantum cascade laser by molecular beam epitaxy is reported. Optimized growth conditions including substrate temperature, V/III ratio, growth rates, doping levels and interface control are summarized. Double crystal Xray diffraction and cross-sectional transmission electron microscopy disclose that our grown InP-based heteroepitaxial structure for quantum cascade laser has excellent periodicity and sharp interfaces. (C) 2005 Elsevier B.V. All rights reserved.

Energy band design for Si/SiGe quantum cascade laser

This paper introduces in detail the working principle of Si/SiGe Quantum cascade laser(QCL). Appropriate parameters are used to calculate the hole subband structure of Si/Si1-xGex quantum well using a six-band k center dot p method. The dispersion relation and energy band for different layer thickness and compositions are investigated. Meanwhile, the energy separations between hole subbands in Si/Si1-xGex/Si quantum wells are also analyzed. Finally the calculated results are used for the Si/SiGe QCL design, which will be beneficial to the structure optimization of Si/SiGe QCL.

Low-threshold high-temperature operation of lambda similar to 7.4 mu m quantum cascade lasers

We report low-threshold high-temperature operation of 7.4 mu m strain-compensated InGaAs/InAlAs quantum cascade lasers (QCLs). For an uncoated 22-mu m-wide and 2-mm-long laser, the low-threshold current densities, i.e. 0.33 kA/cm(2) at 81 K in pulsed mode and 0.64 kA/cm(2) at 84 K in cw mode, are realized. High-temperature operation of uncoated devices, with a high value of 223 K, is achieved in cw mode.

Low threshold current density operation of strain-compensated quantum cascade laser

We report the low threshold current density operation of strain-compensated In0.64Ga0.36As/In0.38Al0.62As quantum cascade lasers emitting near 4.94 mu m. By employing an enlarged strain-compensated structure and optimizing the injector doping density, a rather low threshold current density of 0.57 kA/cm(2) at 80K is achieved for an uncoated 20-mu m-wide and 2.5-mm-long laser.

Design of Low-Loss Surface-Plasmon Quantum Cascade Lasers

National Research Projects of China 60525406 60736031 60806018 60906026 2006CB604903 2007AA03Z446 2009AA03Z403

Design and characteristics of quantum cascade laser-based CO detection system

National High Technology Research and Development Program of China 2007AA03Z112；Program of Ministry of Education of China 20060183030；Program of Jilin Provincial Science and Technology Department of China 20070709；Program of Bureau of Science and Technology of Changchun City 2007107

High-duty-cycle operation of GaAs/AlGaAs quantum cascade laser above liquid nitrogen temperature

We present a detailed study of lambda similar to 9.75 mu m GaAs/AIGaAs quantum cascade lasers. For a coated 2-mm-long and 40-mu m-wide laser, an optical power of 85 mu W is observed 95% duty cycle at 80 K. At a moderate driving pulse (1 kHz and 1% duty cycle), the device presents a peak power more than 20 mW even at 120 K. At 80 K, the fitted result of threshold current densities shows evidence of potential cw operation.

High-power and low-threshold-current-density GaAs/AlGaAs quantum cascade lasers

We report on the realization of GaAs/AlGaAs quantum cascade lasers with an emission wavelength of 9.1 mu m above the liquid nitrogen temperature. With optimal current injection window and ridge width of 24 and 60 mu m respectively, a peak output power more than 500 mW is achieved in pulsed mode operation. A low threshold current density J(th) = 2.6 kA/cm(2) gives the devices good lasing characteristics. In a drive frequency of 1 kHz, the laser operates up to 20% duty cycle.

Realization of GaAs/AlGaAs quantum-cascade lasers with high average optical power

Quasi-continuous-wave operation of GaAs/AlGaAs quantum-cascade lasers with high average optical power is demonstrated. Double X-ray diffraction has been used to investigate the quality of the epitaxial material. The compositional gradients and the interface quality are controlled effectively. The corrected average power of per facet about 17 mW and temperature tuning coefficient of the gain peak about 0.91 nm/K from 83 K to 140 K is achieved in pulse operation. Best value of threshold current density is less than 3.0 kA/cm(2) at 83 K. (C) 2005 Elsevier Ltd. All rights reserved.

Realization of low threshold of InGaAs/InAlAs quantum cascade laser

By optimizing the molecule beam epitaxy growth condition, the quality of quantum cascade (QC) material has greatly been improved. The spectrum of double x-ray diffraction indicates that the interface between the constituent layers is very smooth, the lattice mismatch between the epilayer and the substrate is less than 0.1%, and the periodicity fluctuation of the active region is not more than 4.2%. The QC laser with the emission wavelength of about 5.1 mum is operated at the threshold of 0.73 kA/cm(2) at liquid nitrogen temperature with the repetition rate of 10kHz and at a duty cycle of 1%. Meanwhile, the performance of the laser can be improved with suitable post process techniques such as the metallic ohmic contact technology.

Correlation of structural and optical investigation of InGaAs/InAlAs quantum cascade laser

Double X-ray diffraction has been used to investigate InGaAs/InAlAs quantum cascade (QC) laser grown on InP substrate by molecule beam epitaxy, by means of which, excellent lattice matching, the interface smoothness, the uniformity of the thickness and the composition of the epilayer are disclosed. What is more, these results are in good agreement with designed value. The largest lattice mismatch is within 0.18% and the intersubband absorption wavelength between two quantized energy levels is achieved at about lambda = 5.1 mum at room temperature. At 77 K, the threshold density of the QC laser is less than 2.6 kA/cm(2) when the repetition rate is 5 kHz and the duty cycle is 1%. (C) 2003 Elsevier Science B.V. All rights reserved.

Realization of quantum cascade laser operating at room temperature

X-ray diffraction, as an effective probe and simple method, is used to ascertain the precise control of the epilayer thickness and composition. Intersubband absorption from the whole structure of the QC laser is used to monitor the wavelength of the QC laser and the material quality. Path for growth of high-quality InP-based InGaAs/InAlAs quantum cascade laser material is realized. The absorption between two quantized energy levels is achieved at similar to4.7 mum. Room temperature laser action is achieved at lambda approximate to 5.1 - 5.2 mum. For some devices, if the peak output power is kept at 2 mW, quasi-continuous wave operation at room temperature can persist for more than I It. (C) 2002 Elsevier Science B.V. All rights reserved.

Growth and characterization of InGaAs/InAlAs quantum cascade lasers

The growth and characterization of quantum cascade (QC) lasers based on InGaAs/InAlAs material system are investigated. Pronounced intersubband absorption from stacked active region of QC structure is used to monitor the wavelength of QC laser and disclose the material quality. The precise control of the epilayer thickness and the good quality of interfaces are demonstrated by the abundant narrow satellite peaks of X-ray diffraction. Laser action in quasi-continuous wave operation is achieved at lambda approximate to 5.1-5.2 mum up to 300 K. For 10 x 800 mum(2) laser device, peak output power of similar to7.2 mW and threshold current density of 3 kA/cm(2) at room temperature are obtained. For some devices, if keep the peak output powers at the similar to2 mW level, quasi-continuous wave operation at room temperature persists more than 1 h are recorded. (Q) (C) 2001 Elsevier Science Ltd. All rights reserved.

Investigation on InGaAs/InAlAs quantum cascade lasers

The preparation and main characteristics of the InGaAs/InAlAs quantum cascade laser were given. The device has a reinforced ridge waveguide structure. The threshold current obtained at 80K is about 0. 5A, and the corresponding threshold current density is about 5kA/cm(2).

Strain-compensated quantum cascade lasers operating at room temperature

Quantum cascade (QC) lasers based on strain-compensated InxGa(1-x)As/InyAl(1-y)As grown on InP substrate using molecular beam epitaxy is reported. The epitaxial quality is demonstrated by the abundant narrow satellite peaks of double-crystal X-ray diffraction and cross-section transmission electron microscopy of the QC laser wafer. Laser action in quasi-continuous wave operation is achieved at lambda approximate to 3.6-3.7 mum at room temperature (34 degreesC) for 20 mum x 1.6 mm devices, with peak output powers of similar to 10.6mW and threshold current density of 2.7kA/cm(2) at this temperature. (C) 2000 Published by Elsevier Science B.V.