Double Heterostructure Laser Diodes Research Articles

Dual gate material (Au and Pt) based double-gate MOSFET for high-speed devices

Aluminium Gallium Arsenide (AlGaAs) is a semiconductor material used in the latest design of double heterostructure laser diodes. This semiconductor is mostly available in the arbitrary alloy form between Gallium Arsenide and Aluminium Arsenide. It is derived from the Tri-MethylGallium (TMG/TMGa), and Arsine (AsH3), both the chemicals are pyrophoric and toxic. The resistance is less between source and drain contacts in the case of AlGaAs so that it has been proposed as a material to grow contacts on Indium Phosphide (InP) layer. The AlGaAs uses an ion implantation model for a design purpose which lowers the thermal power while the operation of the device. The parasitic capacitance has to be taken care of while designing a device using this material since the capacitance affects much in the AlGaAs based devices. The average velocity of the electrons has been observed to be increased by 14.63 % in the Au-gate (gate-1) and Pt-gate (gate-2) material-based Double-Gate (DG) MOSFET compared to the Silicon-based DG MOSFET. This paves the way for higher electron mobility, in turn, it can be used in highfrequency device manufacturing. The proposed material can be used in high-speed hybrid applications such as HEMTs and radiofrequency devices for long-haul communication.

Compact laser radar based on a subnanosecond laser diode transmitter and a two-dimensional CMOS single-photon receiver

A pulsed TOF laser radar utilizing the single-photon detection mode has been implemented, and its performance is characterized. The transmitter employs a QW double-heterostructure laser diode producing 0.6 nJ/100 ps laser pulses at a central wavelength of ∼810 nm. The detector is a single-chip IC manufactured in the standard 0.35-μm HV CMOS process, including a 9×9 single-photon avalanche diode (SPAD) array and a 10-channel time-to-digital converter (TDC) circuit. Both the SPAD array and the TDC circuit support a time gating feature allowing photon detection to occur only within a predefined time window. The SPAD array also supports a 3×3 SPADs subarray selection feature to respond to the laser spot wandering effect due to the paraxial optics and to reduce background radiation-induced detections. The characterization results demonstrate a distance measurement accuracy of +/−0.5 mm to a target at 34 m having 11% reflectivity. The signal detection rate is 28% at a laser pulsing rate of 100 kHz. The single-shot precision of the laser radar is ∼20 mm (FWHM). The deteriorating impact of high-level background radiation conditions on the SNR is demonstrated, as also is a scheme to improve this by means of detector time gating.

(Electronics and Photonics Division Award Address) Compound Semiconductor Science and Technology: A Retrospective

From the earliest days, there has been interest in GaAs and other compound semiconductors due to higher electron mobility than silicon and suitability for optical applications. It was shown in 1962 that semiconductors such as silicon are not suitable for lasers and compound semiconductors were suggested. In the fall of 1962, several groups demonstrated semiconductor lasers under pulsed conditions at 77 K and double heterostructure (DH) laser diodes were achieved in 1970. Coinciding with major advances in fiber optics technology, this provided an enormous impetus for the development of compound semiconductor technology. Epitaxial crystal growth is a most important part of the technology. Liquid phase epitaxy was initially used but was replaced by vapor-phase and molecular beam epitaxy. MOCVD eventually became the vapor-phase technique of choice. Following a breakthrough in GaN technology in the 1990s, the impact of GaN technology is enormous and GaN-based LEDs are rapidly becoming the lighting technology of choice.

The concentration of energy from Edge Lasers by Diffractive Optical Component

The aim of this paper is to design a diffractive optical element based on the laser junction numerical model. We assumed a ?long? laser junction emitting quasi-monochromatic, spatially incoherent light that corresponds to the high power laser. Diffractive optics approach can be used due to the narrowband illumination. The especially designed numerical junction model was experimentally verified. Then a numerically designed diffractive focusing element was manufactured and tested in the experimental setup. This paper includes theoretical investigations, numerical modeling as well as experimental data. Full Text: PDF ReferencesE. Wolf, "New theory of partial coherence in the space?frequency domain. Part I: spectra and cross spectra of steady-state sources", J. Opt. Soc. Am. 72, 343 (1982). CrossRef E. Wolf, "Coherence theory of laser resonator modes", J. Opt. Soc. Am. A 1, 541 (1984). CrossRef A. Naqwi and F. Durst, "Focusing of diode laser beams: a simple mathematical model", Appl. Opt. 29, 1780 (1990) CrossRef J. Yang, T. Chen, G. Ding and X. Yuan, "Focusing of diode laser beams: a partially coherent Lorentz model", Proc. SPIE 6824, 68240A (2007); CrossRef X. Zeng and A. Naqwi, "Far-field distribution of double-heterostructure diode laser beams", Appl. Opt. 32, 4491 (1993). CrossRef Y. Li and J. Katz, "Nonparaxial analysis of the far-field radiation patterns of double-heterostructure lasers", Appl. Opt. 35, 1442 (1996). CrossRef X. Zeng, Z. Feng, and Y. An, "Far-field expression of a high-power laser diode", Appl. Opt. 43, 5168 (2004) CrossRef J. Tervo, J. Turunen, P. Vahimaa, and F. Wyrowski, "Shifted-elementary-mode representation for partially coherent vectorial fields", J. Opt. Soc. Am. A 27, 2004 (2010). CrossRef J. Turunen, "Elementary-field representations in partially coherent optics", J. Mod. Opt. 58, 509 (2011). CrossRef H. Partanen, J. Tervo, and J. Turunen, "Spatial coherence of broad-area laser diodes", Appl. Opt. 52, 3221 (2013) CrossRef M. Sypek, "Light propagation in the Fresnel region. New numerical approach", Opt. Commun., 116, 43 (1995) CrossRef Z. Jaroszewicz, A. Kolodziejczyk, M. Sypek, C. Gomez-Reino, "Non-paraxial analytical solution for the generation of focal curves", J. Mod. Opt., 43, 617 (1996) CrossRef M. Sypek, C. Prokopowicz, M. Gorecki, "Image multiplying and high-frequency oscillations effects in the Fresnel region light propagation simulation", Opt. Eng., 42, 3158 (2003) CrossRef C. Prokopowicz, "Numerical calculation of light propagation in off-axis region", Proc. SPIE, 5484, 482 (2004). CrossRef A. Sobczyk, Z. Jaroszewicz, A. Kolodziejczyk, A. Kowalik, Cz. Prokopowicz, M. Sypek, "Nonparaxial anamorphic diffractive lenses", J. Opt., 15, 025702 (1-5) (2013) CrossRef

ATLAS simulation of a laser diode for free space optical communication (FSOC) in mid-infrared spectral region

AbstractIn this paper, simulation studies on an N+-InAs0.61Sb0.13P0.26/n0-InAs0.97Sb0.03/P+-InAs0.61Sb0.13P0.26 double heterostructure laser diode suitable for use as a source in a free space optical communication system at 3.7 μm at room temperature has been presented. The device structure has been characterized in terms of energy band diagram, electric field profile, and carrier concentration profile using ATLAS simulation tool from Silvaco. The current-voltage characteristics of the structure have been estimated taking into account the degeneracy effect. The results of simulation have been validated by the reported experimental results.

Absorption cross-sections of hole polarons in glassy and β-phase polyfluorene

Absorption induced by electrochemically injected holes is studied in poly-9,9-dioctylfluorene (PFO) films. Injected charges form positive polarons which are delocalised over four fluorene units in the glassy phase and about seven fluorene units in its β-phase. Polaron absorption cross-sections at the 640nm peak are similar to the published values of chemically reduced oligofluorenes in solution. The absorption cross-section of polaron in the β-phase at 470nm is about eight times smaller than the stimulated emission cross-section derived from published data. This indicates that β-phase-rich PFO is an attractive candidate for a light-emitting layer in double-heterostructure organic laser diodes.

Optical properties of GaInP/GaAs:Er,O/GaInP laser diodes on p-type GaAs substrates grown by organometallic vapor phase epitaxy

Optical properties of GaInP/GaAs:Er,O/GaInP double heterostructure (DH) laser diodes (LDs) grown by organometallic vapor phase epitaxy (OMVPE) were investigated. The Er-doped LDs showed laser emission of the GaAs band-edge. The threshold current density (Jth) was 3.6 kA/cm2 on the n-type GaAs substrates and 15.8 kA/cm2 on the p-type at 77 K. The Er-doped LDs on the n-type substrate showed a strong sulfur (S)-related emission in the near-infrared region. Conversely, the S-related emission was strongly suppressed in the LDs on the p-type substrates. This was achieved by preventing the incorporation of S atoms into the GaAs active layer. For the electroluminescence (EL) properties, 1.54 μm-emission from Er3+ ions was clearly observed in the Er-doped LDs on p-type substrates. The dependence of EL intensities on the current density showed that the suppression of an energy transfer from the Er3+ ion to the S-related emission was necessary for efficient Er3+ emission at the stimulated emission region of the GaAs band-edge.

Catastrophic Optical-damage in High-power, Broad-area Laser-diodes

AbstractA detailed description of the phenomenon of catastrophic optical-damage (COD) in short (380μm cavity-length), 12μm aperture, proton-bombarded, double-heterostructure laser-diodes with uncoated facets was first presented in 1974. In these devices, COD generally initiates at the facets due to high optical-power density and propagate along transverse-mode filaments. To achieve reliable operation at high optical-power, broad-area laser-diodes have evolved to long (several-millimeter cavity-length), wide-aperture (50-200μm), dielectric-defined, broadened-waveguide, separate-confinement, double-heterostructure, quantum-well laser-diodes with coated, passivated facets. COD in these devices involve both transverse modes and ring-cavity modes.

GaAs emission from GaInP/Er,O‐Co doped GaAs/GaInP laser diodes grown by organometallic vapor phase epitaxy

AbstractWe have fabricated GaInP/Er,O‐codoped GaAs (GaAs:Er,O)/GaInP double heterostructure (DH) laser diodes (LDs) by organometallic vapor phase epitaxy (OMVPE) and investigated their lasing characteristics at GaAs band‐edge. Laser emission at the GaAs band‐edge was observed from the DH LDs at room temperature. The threshold current density (Jth) increased by doping of Er. The slope of the Jth against the reciprocal cavity length (1/L) also increased by the Er doping, indicating reduced relaxation time of injected carriers in GaAs:Er,O. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

An improved transmission line laser model for multimode laser diodes incorporating thermal effects

An improved transmission line model to study the thermal effects in semiconductor laser diodes is reported in this paper. The temperature effects in the laser characteristics are obtained by incorporating temperature dependent gain and carrier density equations for the laser cavity. These primary factors are introduced in the regular transmission line laser model to estimate the static and dynamic characteristics of an 1.3μm InGaAsP double heterostructure laser diode. The results show good agreement with the experimental observation and solution of rate equations referred in the literature. The key feature of this model is that it provides the laser spectra at various temperatures. Based on the model, time dependent evolution of optical spectrum, temperature dependent optical output and frequency chirp are evaluated. Further the distribution of photon and electron density within the cavity is also determined.

Numerical Device Simulation of Double-Heterostructure Organic Laser Diodes Including Current-Induced Absorption Processes

We investigate the impact of induced absorption caused by injected charge carriers and excited states on the threshold current density of an organic laser diode using numerical simulations. The electrical properties of the device are described by a self consistent drift-diffusion model. The optical properties are calculated using a transfer matrix method. Nonradiative annihilation processes are included employing typical rate constants. In our approach, a three-layer double-heterostructure (DH) with typical organic material properties is studied, which exhibits a threshold current density of 564 A/cm2. For this virtual device, upper limits for the charge carrier and triplet-triplet absorption cross section sigmacarrier=1.53times10-3middotsigmaSE and sigmaT 1 TN=4.34times10-3middotsigmaSE have been calculated as a function of the stimulated emission cross section sigmaSE. Additionally, the role of device geometry and material properties concerning induced absorptions is studied. It is shown that the impact of absorption processes is not strongly influenced by the device geometry. By increasing the charge carrier mobilities to mu = 2 cm2/Vmiddots in the transport layers and mu = 0.2 cm2/Vmiddots in the emission layer, the impact of polaron absorption can be greatly reduced. In this case, laser operation might still be possible if sigmacarrier and sigmaSE are within the same order of magnitude. Decreasing the triplet lifetime tau T 1 is a promising way to reduce the impact of triplet-triplet absorption. For sigmaT 1 TN and sigmaSE being within the same order of magnitude, the triplet lifetime tau T 1 has to be reduced to 1 ns for laser operation.

Far-Field Distributions of Double-Heterostructure DiodeLasers: an Improved Non-Equiphase Model

A non-equiphase Gaussian model is proposed to simulate the far-fielddistributions of double-heterostructure diode lasers, which isphysically reasonable because the phase along the junction of diodelasers could not be equal. A comparison of the numerically calculatedintensity profiles in using the equal phase and non-equiphase modelswith the experimentally measured intensity profiles given by Nemotoshows that in the x direction perpendicular to the junctionplane, the non-equiphase Gaussian model is as good as the equal phaseGaussian model. Specifically, in the y direction parallel to thejunction plane and the 45° direction with respect to the xaxis in the xoy plane, the numerical results by using thenon-equiphase model are in good agreement with the experimental data,as the propagation distance is larger than a certain value.

Reduced free carrier absorption loss in midinfrared double heterostructure diode lasers grown by liquid phase epitaxy

An improved InAsSb∕InAsSbP double heterojunction ridge laser was designed and grown by liquid phase epitaxy. The cladding layer absorption loss was minimized by the introduction of two undoped quaternary layers on either side of the active region to form a five layer epitaxial structure. The inserted layers also helped alleviate interdiffusion of unwanted dopants into the active region and reduced current leakage in the device. The resulting diode lasers operate readily in pulsed mode near 3.5μm at elevated temperatures and with a threshold current density as low as 118Acm−2 at 85K. Compared to the conventional three-layer double heterostructure laser, the modified structure with reduced optical loss increased the maximum lasing temperature by 95–210K.

MBE growth of TlInGaAs/TlInP/InP SCH LD structures and their laser operation with low-temperature variation of lasing wavelength

TlInGaAs/TlInP/InP separate confinement heterostructures (SCHs) were grown by gas-source molecular-beam epitaxy and metal stripe laser diodes (LDs) were fabricated. Temperature variation of electroluminescence (EL) peak wavelength was as small as 0.01 nm/K. Pulsed laser operation was achieved at 77–302 K. Threshold current density for the TlInGaAs/TlInP/InP SCH LD (0.6 kA/cm 2 at 77 K) was smaller than that for the TlInGaAs/InP double heterostructure LD (0.8 kA/cm 2 at 77 K). This is due to the increased refractive index of TlInP and the improved optical confinement. Temperature variation of main peak wavelength in the lasing spectra was as small as 0.06 nm/K. This is smaller than that of InGaAsP/InP DFB LDs.

Non-equiphase Hermite–Gaussian model of diode laser beams

A non-equiphase Hermite–Gaussian model is proposed to describe the field in the plane parallel to the junction of double-heterostructure (DH) diode laser beams. The analytical expression for the far field of DH diode laser beams is derived and used to compare the calculated intensity profiles with the measured and calculated values given by Nemoto and Zeng et al., showing a further improvement between the calculated and measured profiles by using the non-equiphase Hermite–Gaussian model.

Optical properties of TlInGaAs/TlInP/InP laser diodes

AbstractTlInGaAs/TlInP/InP separate confinement heterostructures (SCHs) were grown by gas‐source molecular‐beam epitaxy and metal stripe laser diodes (LDs) were fabricated. Temperature variation of electroluminescence peak wavelength was as small as 0.06 nm/K due to the reduced temperature variation of band gap energy of TlInGaAs. Pulsed laser operation was achieved at 77–297 K. Threshold current density for the TlInGaAs/TlInP/InP SCH LD (0.6 kA/cm2 at 77 K) was smaller than that for the TlInGaAs/InP double heterostructure LD (0.8 kA/cm2 at 77 K), which is due to the increased refractive index for TlInP and the improved optical confinement. Temperature variation of main peak wavelength in the lasing spectra was as small as 0.07 nm/K, which is much smaller than those for the InGaAsP/InP Fabry–Perot LDs (0.4 nm/K) and distributed feed‐back LDs (0.1 nm/K). (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Localization Effects in InGaN/GaN Double Heterostructure Laser Diode Structures Grown on Bulk GaN Crystals

We demonstrate a double heterostructure (DH) nitride laser diode (LD) with an untypically wide 9.5 nm InGaN active region instead of the commonly used narrow InGaN quantum wells. Structures were grown on bulk GaN, which ensures low dislocation densities and therefore low concentrations of nonradiative recombination centers. The efficient screening of polarization induced electric fields in the structures under investigation, which contained heavily (1×1019 cm-3) Si doped barriers, was demonstrated by means of hydrostatic pressure dependent photoluminescence measurements on a simplified sample with identical active region. Since the detrimental separation of carriers by electric fields becomes more pronounced for wider InGaN active regions, efficient screening of polarization induced electric fields is essential for the investigated heterostructures. Optical and electrical parameters of this LD were comparable to those of comparable devices with typical QWs of ∼4 nm as active region. We observed a high thermal stability of the photoluminescence intensity and, via time-resolved photoluminescence, a relatively temperature-independent radiative decay time. These observations support the significance of carrier localization phenomena for the radiative recombination processes of the investigated structure. The implications of these results for DH LD structures are discussed.

Direct determination of the free-carrier injection density, the free-carrier absorption, and the recombination factors in double heterostructure diodes by optical phase measurements. Part III

Accurate phase measurements over a temperature interval on double heterostructure laser (DH) diodes provide a means to directly measure the injected free-carrier density and the free-carrier absorption as a function of the injected current. This paper describes the underlying principles and demonstrates the validity of the simple concepts. The data permit to deduce the radiative and nonradiative recombination factors in nominally undoped active layers without taking resource to luminescence measurements. The results presented on GaAs and InGaAsP lattice matched to InP DH diodes show a good overall agreement with calculations based on a heuristic model. The radiative recombination factors at room temperature are near 5.3×10−11 and 2.0×10−11cm3s−1 for GaAs and for InGaAsP with a band gap of 1.122eV, respectively. The free-carrier absorption due to the injected carriers is strongly dispersive and proportional to the 2.3rd power of the wavelength. We show a strong temperature dependence of the free-carrier absorption that is more important in InGaAsP than in GaAs. The results are internally consistent without the need of any free parameter. The phase measurements can also be used to characterize the heat chirping of the active layers under pulsed current excitation.

Energy band gaps of Zn1−xMgxSySe1−y lattice matched to GaAs

Abstract We report on theoretical study of the energy band gaps for the quaternary alloys Zn1−xMgxSySe1−y in conditions of lattice matching to GaAs substrates using simply the empirical pseudopotential method under the virtual crystal approximation which takes into account the effects of compositional disorder. Our results agree generally very well with the available experimental data. It is shown that the band-gap energies of Zn1−xMgxSySe1−y are expressed by the parabolic function of the composition considering the bowing parameter and that Zn1−xMgxSySe1−y can be a direct or an indirect semiconductor depending on the alloy composition. The Zn0.35Mg0.65S0.6Se0.4 is predicted to meet requirement of the cladding layer for fabricating blue double heterostructure laser diodes using ZnS0.06Se0.94 as the active layer.

Tunable 3.3 μm InAsSb/InAsSbP diode lasers: a new concept of fast lasing due to nonlinear optical effects

InAsSb/InAsSbP double heterostructure diode lasers for the spectral range of 3.3 μm grown by liquid phase epitaxy have been investigated. Emission spectra, far–field patterns and wavelength tuning versus current have been studied in the wide current range from threshold value I th up to 3 I th at the temperature of liquid nitrogen. Controlled by current, wavelength tuning in single–mode lasing has been obtained both towards the shorter wavelengths (up to 4.56 cm−1) and towards the longer wavelengths (up to 0.9 cm−1) at the temperature T = 77 K. Comparison of the emission properties of the lasers, driven by different types of current (short pulse current, sawtooth pulse current and in quasi–continuous–wave (CW) regime) showed the same quantum–mechanical nature of current tuning. The theoretical model of this nonlinear optical phenomenon is proposed. The estimated times of current tuning defined mainly by the photon lifetime in the cavity are ca. 10−9 to 10−12 s.