-
[show abstract]
[hide abstract]
ABSTRACT: We investigate the electronic energy levels and carrier dynamics in InAs / In <sub> x </sub> Ga <sub>1- x </sub> As dots-in-a-well (DWELL) structure by comprehensive spectroscopic characterization over a temperature range from 10 to 300 K. The integrated photoluminescence (PL) intensity is observed to increase with raising temperature up to 100 K. Through combining the PL and PL excitation (PLE) analysis, we provide direct evidence that this anomalous temperature dependence of the PL spectrum is due to the carrier trapping in InGaAs quantum well at low temperature. A rate equation model is adopted to quantitatively describe the thermal escape and capture processes of carriers in the DWELL system. The origin of thermal activation energies for quantum dot PL quenching at higher temperatures is discussed referring to the electronic energy levels revealed by PLE spectra.
Journal of Applied Physics 02/2010; · 2.17 Impact Factor
-
N K Metzger,
C G Leburn,
A A Lagatsky,
C T A Brown,
S Calvez,
D Burns, H D Sun,
M D Dawson,
M Le Dû,
J C Harmand,
W Sibbett
[show abstract]
[hide abstract]
ABSTRACT: The operation of a femtosecond Cr(4+):YAG laser that incorporates a novel GaInNAsSb semiconductor saturable Bragg reflector is reported. In the mode-locked regime 230 fs pulses centred at 1528 nm were generated at an average output power of 280 mW. The SESAM exhibited a low saturation fluence of 10 microJ/cm(2) and a short recovery time of 12 ps.
Optics Express 12/2008; 16(23):18739-44. · 3.59 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The effect of quantum-well intermixing on the material gain of a GaInNAs/GaAs quantum-well laser is investigated theoretically. The diffusion of gallium and indium atoms in the intermixed sample is assumed and their compositional profiles are modelled using Fick's law. The band-anti-crossing model is used to calculate the band structure of the GaInNAs quantum well, which is appropriate for this non-randomly-alloyed material system. The calculated results show good agreement with the observed photoluminescence excitation for both non-intermixed and intermixed samples, which confirms this model. It is found that the strain gradient, the variation of material band gap and the degeneracy between heavy and light holes are the main factors determining the quantized energy levels of the intermixed quantum well. With the increase of diffusion length, the material gain and differential gain decrease due to the increase of the conduction band effective mass and the rapid decrease of the dipole moments. These characteristics of quantum-well intermixing effects will be useful in the design of integrated photonic devices based on this material.
Semiconductor Science and Technology 08/2008; 23(9):095010. · 1.72 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We describe the operation of a femtosecond Cr<sup>4+</sup>:YAG laser that has been mode locked using a novel GaInNAsSb SESAM. 230 fs pulses were generated at an average output power of 280 mW.
Lasers and Electro-Optics, 2008 and 2008 Conference on Quantum Electronics and Laser Science. CLEO/QELS 2008. Conference on; 06/2008
-
S. Calvez,
N. Laurand, H. D. Sun,
J. Weda,
D. Burns,
M. D. Dawson,
A. Harkonen,
T. Jouhti,
M. Pessa,
M. Hopkinson,
D. Poitras,
J. A. Gupta,
C. G. Leburn,
C. T. A. Brown,
W. Sibbett
[show abstract]
[hide abstract]
ABSTRACT: After a decade of intensive research on GaInNAs(Sb) on GaAs alloys, this paper summarizes some of the key properties of these III–V alloys and presents current progress in their exploitation in a variety of surface-normal operating devices such as Vertical (External)-Cavity Surface-Emitting Lasers (V(E)CSELs) and SEmiconductor Saturable Absorber Mirrors (SESAMs). (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Physica Status Solidi (A) Applications and Materials 12/2007; 205(1):85 - 92. · 1.46 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The authors report the temperature dependent photoluminescence characteristics of a series of Ga In N As Sb / Ga ( N ) As double quantum wells which all emit at 1.5–1.55 μ m at room temperature and whose design is such that the quantum wells have nominally identical valence band profiles but show different confinement depth in the conduction band. The photoluminescence quenching at high temperature demonstrates a thermal activation energy independent of the conduction band offset and can be most plausibly attributed to the unipolar thermalization of holes from the quantum wells to the barriers. This effect will intrinsically limit the flexibility of heterostructure design using GaInNAs(Sb), as it would for any other material system with small valence band offset.
Applied Physics Letters 10/2006; · 3.84 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We report the use of a volume Bragg grating as an output coupler mirror to improve and stabilize the spectral characteristics of 1058-nm vertical-external-cavity surface-emitting laser which is thermally managed using an intracavity diamond heatspreader. Spectrally narrow and locked emission with up to 645mW of TEM<sub>0,0</sub> output power is demonstrated
IEEE Photonics Technology Letters 09/2006; · 2.19 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The 1.55 μm pulsed operation of an optically-pumped GaInNAsSb vertical-cavity surface-emitting laser (VCSEL) is reported. The structure employs a dielectric (SiO<sub>2</sub>/TiO<sub>2</sub>) top mirror, while the bottom mirror and active region were grown on GaAs by MBE. Temperature-dependent (10-40°C) laser measurements were made for an as-grown sample and an annealed sample, both having a room-temperature lasing wavelength of 1547 nm. Results indicate an annealing-induced blue-shift of the gain peak
Electronics Letters 02/2006; · 0.96 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We report the photoluminescence characterization of a series InNAs/InGaAs multi-quantum wells (MQWs) of various N content on InP substrates. The emission wavelength of these QWs can be tuned effectively by N content. However, the bowing effect is weaker than in GaNAs and GaInNAs. The optical properties of these hetero-structures are closely related to quality of the interface between the barriers and the QWs which is influenced by N content. Two effects of N in this material system have been clarified. On the one hand, the incorporation of N into InAs matrix is beneficial as far as the reduction of band-gap and the lattice constant are concerned. On the other hand, the PL efficiency increases dramatically with the increase of N content. Optimized design and growth could be achieved by trading off between these two effects.
Indium Phosphide and Related Materials, 2005. International Conference on; 06/2005
-
[show abstract]
[hide abstract]
ABSTRACT: In summary, we have investigated the dependence of the optical properties of GaInNAs QWs grown by MOVPE on GaNAs SCLs and InGaAs SMLs. Introduction of only SCLs between the GaAs and GaInNAs QW deteriorates the epitaxial quality of the QW due to the increased stress between tensile-strained GaNAs and compressive-strained GaInNAs. This detrimental effect of the interface can be countered by the insertion of a layer of InGaAs. Contrary to what observed in MBE, MOVPE-grown GaInNAs QW with combined SCLs/SMLs demonstrated blue-shifted PL due to the decrease N content with improved QW quality.
Indium Phosphide and Related Materials, 2005. International Conference on; 06/2005
-
[show abstract]
[hide abstract]
ABSTRACT: We report optical studies of high-quality 1.3 μm strain-compensated GaInNAs/GaAs single-quantum-well structures grown by metalorganic vapor phase epitaxy. Photoluminescence excitation (PLE) spectroscopy shows clearly the electronic structure of the two-dimensional quantum well. The transition energies between quantized states of the electrons and holes are in agreement with theoretical calculations based on the band anti-crossing model in which the localized N states interact with the extended states in the conduction band. We also investigated the polarization properties of the luminescence by polarized edge-emission measurements. Luminescence bands with different polarization characters arising from the electron to heavy-hole and light-hole transitions, respectively, have been identified and verify the transition assignment observed in the PLE spectrum.
Applied Physics Letters 02/2005; 86(9):092106-092106-3. · 3.84 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We report the photoluminescence characteristics of molecular beam epitaxy grown GaInNAs/GaAs single quantum wells that emit near 1.5-m wavelength at room temperature. The photoluminescence properties were investigated by varying the excitation wavelength, excitation intensity and sample temperature. It is found that the spectroscopic properties in the 1.5-m material are quite different from those of similar GaInNAs/GaAs structures emitting at 1.2m. The related radiative mechanisms in the 1.5-m samples are interpreted in terms of the optical transitions of phase-separated quantum-dot states rather than quantum-well states.
Applied Physics A 12/2004; 80(1):9-12. · 1.63 Impact Factor
-
H.D. Sun,
A.H. Clark,
S. Calvez,
M.D. Dawson,
H.Y. Liu,
M. Hopkinson,
P. Navaretti,
M. Gutierrez,
J.S. Ng,
J.P.R. David,
P. Gilet,
L. Grenouillet,
A. Million
[show abstract]
[hide abstract]
ABSTRACT: Dilute nitride semiconductors are a topic of major current research interest owing to the novel physics induced by the incorporation of N in small percentages of composition. Related research has been further motivated by the favourable characteristics for device applications of the resultant materials, particularly represented by GaInNAs quaternary compounds as active materials in the 1.3-1.6 μm wavelength range. Whilst 1.3-μm GaInNAs/GaAs materials and devices are now reaching a level of maturity, the extension of these structures to around 1.55 μm is still in its infancy. The authors report optical studies of 1.55-μm GaInNAs/GaAs heterostructures of varying characteristics, all grown by molecular beam epitaxy. As the addition of N complicates the local structure and optical properties in this material system, the PL mechanisms are clarified by detailed PL excitation (PLE) spectra. Whereas all the measured samples exhibit strong PL at room temperature, the electronic structure is quite different between samples grown under different conditions. Some demonstrate clearly standard 2-D quantum well (QW) electronic states and some demonstrate evidence of phase-separated quantum-dot-like (QD) structures.
IEE Proceedings - Optoelectronics 11/2004; · 0.71 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The compatibility of GaInNAs/GaAs active regions with AlGaAs Bragg mirror technology opens up a range of surface-normal device formats for the spectral region around 1.3 μm. The authors report recent progress on the development of diode-pumped vertical external-cavity surface emitting lasers (VECSELs) and vertical cavity semiconductor optical amplifiers (VCSOAs) based on this technology. Pertinent performance characteristics are reported for GaInNAs 1.3-μm VECSELs capillary-bonded to diamond heatspreader platelets. In a conventional three-mirror air-spaced laser cavity up to 0.6 W of TEM<sub>00</sub> output power was obtained. With the outer surface of the diamond platelet coated to form a dielectric output coupler mirror, it was possible to obtain the first monolithic microchip operation of a GaInNAs VECSEL, where a Gaussian beam with output power up to 120 mW was obtained. The influence of temperature on the performance of a six-quantum-well VCSOA with on-chip gain values of up to 16 dB was also reported. It reveals that on-chip gain of 9 dB can be achieved over a range of 85°C, allowing the amplifier characteristics to be tuned over more than 9.5 nm. Further investigations of the influence of optical feedback on the performance of these vertical amplifiers demonstrate that a three-mirror analysis explains the observed phenomena.
IEE Proceedings - Optoelectronics 11/2004; · 0.71 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We report the optical characterization of high-quality 1.55 μm GaxIn1−xNyAs1−y multiquantum wells (MQWs), grown on GaAs with Ga(In)N0.01As spacer layers. The transitions between the quantized QW states of the electrons and holes have been identified using photoluminescence excitation spectroscopy. Their energies are consistent with theoretical fitting based on the band anticrossing model. It is also confirmed by detailed spectroscopic measurements that the addition of even a small amount of In to GaN0.01As barriers remarkably improves the optical characteristics of the QWs. The results imply that although strain-compensated GaInNAs MQWs provide a feasible approach to realizing 1.55 μm optical emission, the relative lattice mismatch between the wells and barriers is critical to the optical quality of the related QWs.
Applied Physics Letters 10/2004; 85(18):4013-4015. · 3.84 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We present the 1.55-μm GaInNAs/GaAs multiple quantum well (QW) heterostructures with GaNAs or GaInNAs barrier and space layer (BSL). An enhancement of photoluminescence intensity and a remarkable reduction of emission linewidth of GaInNAs multiple QWs have been demonstrated by using GaInNAs quaternary BSL, instead of GaNAs BSL. These effects of GaInNAs BSL could be understood in term of the improvement of structural properties of GaInNAs QWs. These results present to us a variable approach to further developing GaAs-based light sources in the telecommunication wavelength range near 1.55 μm.
Semiconducting and Insulating Materials, 2004. SIMC-XIII-2004. 13th International Conference on; 10/2004
-
[show abstract]
[hide abstract]
ABSTRACT: We report on the continuous-wave amplification characteristics of an optically pumped 1.3-μm multiple-quantum-well GaInNAs-GaAs vertical-cavity semiconductor optical amplifier (VCSOA). The VCSOA structure was monolithically grown by molecular beam epitaxy and operated in reflection mode in a fiber-coupled system. The maximum on-chip gain attained, limited by the onset of laser action, was 15.6 dB at 196 mW of 980-nm pump power. For a chip gain of 10.4 dB, the optical bandwidth was 10.8 GHz and the saturation output power was -9 dBm. By varying the pump laser power, a maximum extinction ratio of 22.3 dB was obtained. Temperature-controlled tuneable operation of the device is also presented and demonstration of 9 dB of chip gain obtained over 9.5 nm with an optical bandwidth of 12 GHz is reported.
IEEE Journal of Quantum Electronics 08/2004; · 1.88 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: What is believed to be the first high-power vertical external cavity surface emitting laser (VECSEL) operating at 1.3 μm is reported. CW output powers >0.6 W were achieved using a diode-pumped GaInNAs VECSEL structure capillary-bonded to a single-crystal diamond heatspreader.
Electronics Letters 02/2004; · 0.96 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: In this paper, we have demonstrated fibre coupled-diode pumping operation of a six QW GaInNAs/GaAs VCSEL showing performance of up to 4.1 mW output coupled into a single-mode fibre at 10°C at 1290.7 nm. Laser emission was observed up to a temperature of 95°C, and the temperature shift is 0.1 nm/K. The VSCEL structure was grown by solid-source MBE using a nitrogen plasma.
Lasers and Electro-Optics Europe, 2003. CLEO/Europe. 2003 Conference on; 07/2003
-
[show abstract]
[hide abstract]
ABSTRACT: A spin-off from our work on dilute-N GalnNAs VCSELs has been the development of saturable Bragg reflectors (SBR) based on a single 7 nm-thick Ga<sub>0.65</sub>ln<sub>0.35</sub>N<sub>0.019</sub>As<sub>0.981</sub> quantum-well grown midway in the final quarter-wave layer of a 21 pair AlAs/GaAs Bragg mirror. The SBR was used as the modelocking element in the high power 1.3 μm Nd:YLF laser. The laser was operated quasiCW permitting very high power effective 'on-time' operation in a simple side-pumped laser configuration. The laser was pumped with 360 W peak power at 2% duty cycle (200μs at 100 Hz).
Lasers and Electro-Optics Europe, 2003. CLEO/Europe. 2003 Conference on; 07/2003
