Home  About us  Contact
 

Distributed Bragg Reflector (distributed + bragg_reflector)

Distribution by Scientific Domains
Physics and Astronomy90%

Selected Abstracts

The experimental study of a polarization orthogonal single-longitudinal-mode distributed Bragg reflector fiber laser

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 6 2008
Luo Jian-Hua
Abstract In this article, we reported a polarization orthogonal single-longitudinal-mode distributed Bragg reflector (DBR) fiber laser. The laser operated robustly in single longitudinal mode and dual polarizations with frequency difference of 976.93 MHz. This laser has simple structure as well as frequency adjustable. It can be used in a wide range of communication, sensor, and spectroscopic applications. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1658,1660, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23454 [source]

Low thermal resistance, high-speed 980 nm asymmetric intracavity-contacted oxide-aperture VCSELs

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 7 2009
Y. M. Song
Abstract We demonstrated high-speed characteristics of an oxide-aperture vertical-cavity surface-emitting laser (VCSEL) with intracavity structures for both p- and n-contacts, based on InGaAs/GaAs multiple quantum wells operating at , , 980 nm, indicating a low thermal resistance (Rth). The asymmetric current injection scheme is employed for reducing current crowding around the rim of the oxide aperture. A high aluminium content undoped Al0.88Ga0.12As and GaAs distributed Bragg reflector (DBR) mirror is used for efficient heat dissipation. The VCSEL with a 7 ,m oxide aperture exhibited an output power of 2.5 mW and a threshold current of 0.8 mA with a slope efficiency of 0.39 mW/mA at 20 °C under continuous-wave operation and it still worked with 1.3 mW at 90 °C. The temperature tuning coefficient of 0.081 nm/°C and dissipated electrical power tuning coefficient of 0.104 nm/mW were observed, leading to a low Rth of 1.28 °C/mW. A high modulation bandwidth up to 13 GHz with a modulation current efficiency factor of 6.1 GHz/mA1/2 was achieved. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Reflectance and photoluminescence studies of InGaN/GaN multiple-quantum-well structures embedded in an asymmetric microcavity

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 7 2006
D. Y. Lin
Abstract Using reflectance (R) and photoluminescence (PL) measurements InGaN/GaN multiple-quantum-well (MQW) structures embedded in an asymmetric microcavity with different thickness of stacking pairs have been studied. The asymmetric microcavity structures are composed of a cavity sandwitched between the air/semiconductor interface and a mirror using distributed Bragg reflector (DBR). For the DBR with thinner AlN layers the high-reflectivity stop band locates at higher photon energy. The luminescence efficiency and the spectrum of InGaN/GaN multiple-quantum-well structures will be modified by the microcavity. A comparison of PL with R spectra shows that the emission efficiency can be enhanced by matching up the luminescence spectrum coming from the MQW and the high-reflectivity stop band. From the blue shift of the cavity modes as a function of incident angles the refractive index and cavity length can be determined. By measuring the PL spectra as a function of emission angle, it is found that the PL spectra were predominatly determined by microcavity resonances. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

The influence of aluminum composition of AlxGa1,xAs in distributed Bragg reflector on surface morphology

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 12 2004
B. Kim
Abstract Surface morphology of the AlGaAs/GaAs Vertical Cavity Surface Emitting Laser (VCSEL) grown by metalorganic vapor phase epitaxy (MOVPE) was investigated using atomic force microscopy. It is shown that the morphology of the structure strongly depends on the aluminum composition of the low Al content layer of distributed Bragg reflector (DBR) pairs and epi thickness. Whereas a high Al content layer in DBRs had little effect on the surface morphology, it was attributed that the influence of Al composition on the morphology of AlxGa1,xAs on GaAs was stronger in the range of 0 < x < 0.5 than 0.5 < x < 1. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Effects of the artificial Ga-nitride/air periodic nanostructures on current injected GaN-based light emitters

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2005
Bei Zhang
Abstract In this report, III-nitride/air deeply etched one-dimensional (1D) distributed Bragg reflector (DBR) stacks and two-dimensional (2D) photonic octagonal quasi-crystals (8PQCs) were formed on the GaN-based light emitters by focused Ga ion beam (FIB) milling. The effects of these 1D and 2D GaN/air periodic nanostructures on the properties of the GaN-based light emitters were studied by the measurements of microscopic optical reflection, flourescence, electrical luminescence and current-voltage characteristics. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Optimization of Bragg reflectors in AlGaAs/GaAs VCSELs

LASER PHYSICS LETTERS, Issue 5 2005
V. M. N. Passaro
Abstract In this paper a detailed investigation of the distributed Bragg reflectors in GaAs-based vertical cavity surface emitting lasers is presented. The influence of layer doping concentration, number of periods, oxide aperture and AlxGa1,xAs alloy composition on output emission power and threshold current has been found. Both oxidized and non oxidized structures have been considered. A number of interpolation curves are extracted and presented for design and fabrication purposes. Although the results are presented for GaAs-based structures, the theoretical approach is very general. (© 2005 by Astro, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source]

Crack free monolithic nitride vertical-cavity surface-emitting laser structures and pillar microcavities

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 7 2006
Henning Lohmeyer
Abstract We report on the successful fabrication and optical investigation of monolithicly grown GaN based vertical-cavity surface-emitting laser structures featuring quality factors of 250. Short-period AlN/InGaN superlattices are used for the low-index layers of the distributed Bragg reflectors. Pillar microcavities are realized by focused-ion-beam etching. Micro-photoluminescence measurements reveal the longitudinal and transversal mode spectra of the cavities in good agreement with theoretical calculations based on a vectorial transfer matrix method. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

GaN/air gap based micro-opto-electro-mechanical (MOEM) Fabry-Pérot filters

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2007
E. Cho
Abstract Structural and optical properties of Fabry-Pérot filters (FPFs) with GaN/air gap based distributed Bragg reflectors (DBRs) were studied. Reflectance of GaN/air gap DBRs on sapphire substrate was calculated from the standard transmission matrix method and results showed that 98% reflectance is achievable with only 3.5 pairs at a center wavelength of 450 nm. The thickness of the GaN layer and the first AlN layer was determined according to the deformation induced by the residual stress. In-plane strain corresponding to growth conditions and the thickness of the GaN epilayer was considered for this analysis. Optical tuning efficiency and spectral range were found to be 0.27 and 25 nm respectively for FPFs with GaN/air gap (322 nm/113 nm) based DBRs and a ,0/2 air resonant cavity. The calculated pull-in voltage was 1.5 V. Crack free AlN grown on GaN by in-house MOCVD showed an etching rate of 0.2 nm/min. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

(ZnSe/MgS)/ZnCdSe DBRs grown by molecular beam epitaxy using ZnS as a sulphur source

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2006
S. V. Sorokin
Abstract MBE growth and study of optical and structural properties of (ZnSe/MgS)/ZnCdSe distributed Bragg reflectors with , = 520 nm and Rmax = 97% are presented. The samples were grown pseudomorphically on GaAs (001) substrate using ZnS as a sulphur source. The details of MBE growth of such structures are discussed. Scanning electron microscopy, X-ray diffraction and optical measurements demonstrate good optical and structural characteristics of the Bragg reflectors. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

High Reflectivity AlGaN/AlN DBR Mirrors Grown by PA-MBE

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2003
F. Fedler
Abstract High reflectivity (>90%) distributed Bragg reflectors (DBR) have been successfully produced utilizing the AlGaN/AlN material system. We present reflectivity and XRD data of Ga-polar AlxGa1,xN/AlN Bragg reflectors grown on sapphire. High peak reflectivities between 54% (5.5 period mirror) and 97% (25.5 period mirror) combined with large reflectivity FWHM of 30 nm have been found. All reflectors have been designed by ex-situ spectroscopic ellipsometry (SE) data of respective reference samples. [source]