Showing papers on "Laser linewidth published in 1995"
TL;DR: Ytterbium-doped silica fibers exhibit very broad absorption and emission bands, from /spl sim/800 nm to /spl sim/1064 nm for absorption and /spl S sim/970 nm to/spl sim s sim/1200 nm for emission as discussed by the authors.
Abstract: Ytterbium-doped silica fibers exhibit very broad absorption and emission bands, from /spl sim/800 nm to /spl sim/1064 nm for absorption and /spl sim/970 nm to /spl sim/1200 nm for emission. The simplicity of the level structure provides freedom from unwanted processes such as excited state absorption, multiphonon nonradiative decay, and concentration quenching. These fiber lasers therefore offer a very efficient and convenient means of wavelength conversion from a wide variety of pump lasers, including AlGaAs and InGaAs diodes and Nd:YAG lasers. Efficient operation with narrow linewidth at any wavelength in the emission range can be conveniently achieved using fiber gratings. A wide range of application for these sources can be anticipated. In this paper, the capabilities of this versatile source are reviewed. Analytical procedures and numerical data are presented to enable design choices to be made for the wide range of operating conditions. >
564 citations
TL;DR: In this paper, the authors describe a compact, economic and versatile diode laser system based on commercial laser diodes, optically stabilized by means of feedback from a diffraction grating, which offers singlemode operation with a linewidth of a few 100 kHz, continuous scans over 25 GHz, high chirp rates (up to 9 GHz/ms) and FM-modulation up to the GHz range.
519 citations
TL;DR: In this article, the authors examined under what conditions cavity ring-down spectroscopy (CRDS) can be used for quantitative diagnostics of molecular species and showed that CRDS is appropriate for species whose absorption features are wider than the spacing between longitudinal modes of the optical cavity.
Abstract: We examine under what conditions cavity ring-down spectroscopy ~CRDS! can be used for quantitative diagnostics of molecular species. We show that CRDS is appropriate for diagnostics of species whose absorption features are wider than the spacing between longitudinal modes of the optical cavity. For these species, the absorption coefficient can be measured by CRDS without a knowledge of the pulse characteristics provided that the cavity ring-down decay is exponential. We find that the exponential ring-down decay is obeyed when the linewidth of the absorption feature is much broader than the linewidth of the light circulating in the cavity. This requirement for exponential decay may be relaxed when the sample absorption constitutes only a small fraction of the cavity loss and, consequently, the sample absorbance is less than unity during the decay time. Under this condition the integrated area of a CRDS spectral line approximates well the integrated absolute absorption coefficient, which allows CRDS to determine absolute number densities ~concentrations!. We determine conditions useful for CRDS diagnostics by analyzing how the absorption loss varies with the sample absorbance for various ratios of the laser pulse linewidth to the absorption linewidth for either a Gaussian or a Lorentzian absorption line shape. © 1995 American Institute of Physics.
445 citations
TL;DR: In this article, the authors present detailed investigations on a device, which utilizes a semiconductor laser amplifier in a loop mirror configuration (SLALOM), and different modes of operation are reported like nonlinear single pulse switching and two-pulse switching at different operation speeds (1-100 Gb/s).
Abstract: The processing of optical signals in the optical domain is an important issue resulting from the desire to take advantage of the full bandwidth of the optical fiber. In this paper, we present detailed investigations on a device, which utilizes a semiconductor laser amplifier in a loop mirror configuration (SLALOM). Different modes of operation are reported like nonlinear single pulse switching and two-pulse switching at different operation speeds (1-100 Gb/s). Furthermore, a number of applications of the SLALOM in photonic systems, like pulse shaping, decoding, retiming and time-division demultiplexing, are presented. In addition, the SLALOM can be used for an estimate of the linewidth enhancement factor /spl alpha/ and the carrier lifetime /spl tau//sub e/ in an SLA. >
355 citations
TL;DR: The basic physics underlying the approach may be considered a harbinger for the coupling of active photonic microstructures such as microdisk lasers.
Abstract: Morphology-dependent resonances (MDR's) of solid microspheres are excited by using an optical fiber coupler The narrowest measured MDR linewidths are limited by the excitation laser linewidth (<0025 nm) Only MDR's, with an on-resonance to off-resonance intensity ratio of 10(4), contribute to scattering The intensity of various resonance orders is understood by the localization principle and the recently developed generalized Lorentz-Mie theory The microsphere fiber system has potential for becoming a building block in dispersive microphotonics The basic physics underlying our approach may be considered a harbinger for the coupling of active photonic microstructures such as microdisk lasers
286 citations
TL;DR: In this paper, a dual-mode multisection distributed feedback semiconductor laser is used to generate high power signals between 40 and 60 GHz with extremely high spectral purity and stability.
Abstract: This paper presents a new approach to the optical generation of millimeter-wave signals using a dual-mode multisection distributed feedback semiconductor laser. This simple device is capable of generating high power signals between 40 and 60 GHz with extremely high spectral purity and stability. The two optical modes produced by this laser are heterodyned on an ultrafast photodiode to give a beat signal at the mode difference frequency. The phase noise of the beat signal is greatly reduced by phase-locking the modes using an electrical drive signal applied to the laser at a subharmonic of the beat frequency. Millimeter-wave signals are obtained with a linewidth of less than 10 Hz, a phase noise of less than -85 dBc/Hz at 100 kHz offset, and a locking range of about 500 MHz. Millimeter-wave fiber-radio systems are seen as a major application area for these new compact optical sources. >
280 citations
17 Feb 1995
TL;DR: In this article, a good understanding of external optical feedback phenomena in semiconductor laser sources is provided, including linewidth narrowing and broadening, mode hopping phenomena and the transition to the so-called coherence-collapse regime.
Abstract: In optical fiber networks, the semiconductor laser source may be subjected to unavoidable optical feedback from fiber pigtails, fiber connectors and other components, unless expensive optical isolators are used. Therefore, a good understanding of external optical feedback phenomena in semiconductor lasers is required. This paper will review these phenomena, including linewidth narrowing and broadening, mode hopping phenomena and the transition to the so-called coherence-collapse regime. In particular, laser designs with high endurance against optical feedback will be discussed.
242 citations
TL;DR: Stable single-frequency and polarization operation of a traveling-wave, Er(3+)-doped fiber loop laser is demonstrated by incorporating an unpumped Er(+3)- doped fiber section butted against a narrow-band feedback reflector with saturable absorber that acts as a narrow bandpass filter that automatically tracks the lasing wavelength.
Abstract: We demonstrate stable single-frequency and polarization operation of a travelling-wave Er3+:Yb3+-doped fiber loop laser by incorporating an unpumped Er3+-doped fiber section butted against a narrowband feedback reflector. The saturable absorber acts as a narrow bandpass filter which automatically tracks the lasing wavelength, thus ensuring single-frequency operation. Output powers up to 6.2 mW at 1535 nm were obtained for launched pump powers of 175 mW at 1064 nm. At this output, the RIN was less than -112 dB/Hz at frequencies above 200 kHz and the laser linewidth less than 0.95 kHz whilst the lasing frequency was observed to drift slowly (~ 170 MHz/hr) due to environmental effects.
241 citations
TL;DR: It is shown that the guided-mode resonance effects associated with waveguide gratings can be used to realize transmission bandpass filters with high efficiency, narrow linewidth, symmetrical response, and low sidebands.
Abstract: It is shown that the guided-mode resonance effects associated with waveguide gratings can be used to realize transmission bandpass filters. The key idea is the integration of the resonant waveguide gratings into a dielectric multilayer structure that efficiently reflects the off-resonance spectral components while passing the resonant part. This concept is applied to design multilayer transmission bandpass filters with high efficiency, narrow linewidth, symmetrical response, and low sidebands.
175 citations
TL;DR: In this article, a quantum cascade laser at λ = 4.6 μm was reported to operate in continuous wave operation at liquid nitrogen temperature, and the single mode spectrum is temperature tunable over 1.8 cm −1.
Abstract: Continuous wave operation of a quantum cascade laser at λ=4.6 μm is reported above liquid nitrogen temperature. Optical powers of 15 mW at 50 K and 2 mW at 85 K are reported. The single mode spectrum is temperature tunable over 1.8 cm −1. These devices also operated in pulse mode with 20 mW peak power at 200 K. Gain measurements show evidence for ultralow linewidth enhancement factor α<0.1.
170 citations
TL;DR: In this article, a thermal wave resonant cavity was constructed using a thin aluminum foil wall as the intensity-modulated-laser-beam induced oscillator source opposite a pyroelectric polyvilidene fluoride wall acting as a signal transducer and cavity standing-wave-equivalent generator.
Abstract: A thermal‐wave resonant cavity was constructed using a thin aluminum foil wall as the intensity‐modulated‐laser‐beam induced oscillator source opposite a pyroelectric polyvilidene fluoride wall acting as a signal transducer and cavity standing‐wave‐equivalent generator. It was shown that scanning the frequency of oscillation produces the fundamental and higher overtone resonant extrema albeit with increasingly attenuated amplitude—a characteristic of thermal‐wave behavior. Experimentally, scanning the cavity length produced a sharp lock‐in in‐phase resonance with simple linewidth dependencies on oscillation (chopping) frequency and intracavity gas thermal diffusivity. The thermal diffusivity of air at 294 K was measured with three significant figure accuracy: 0.211±0.004 cm2/s. The novel resonator can be used as a high‐resolution thermophysical property sensor of gaseous ambients.
TL;DR: In this paper, a complete model with the spin-orbit coupling for strained quantum-well lasers is presented, and explicit formulas for the momentum-matrix elements are given, and the improvement in the threshold current density of tensile strained quantum well lasers, as compared with that of the unstrained quantum well, is shown to result from the enhanced momentum matrix.
Abstract: A complete model with the spin-orbit coupling for strained quantum-well lasers is presented. Explicit formulas for the momentum-matrix elements are given. The improvement in the threshold current density of tensile strained quantum-well lasers, as compared with that of the unstrained quantum well, is shown to result from the enhanced momentum matrix. The differential gain and the linewidth enhancement factor are calculated. The theoretical results show a smaller linewidth enhancement factor for compressively and tensile strained quantum wells than that of the unstrained structure, as has been experimentally observed. The temperature behavior of both the radiative component and the Anger component of the threshold current density is shown. Due to a decrease of gain and differential gain with increasing temperature, the threshold carrier density in unstrained quantum wells is increased with a large increment of the Auger recombination current at high temperature. For strained quantum wells, this increment is moderate because of the smaller threshold carrier density. >
TL;DR: Sodium atoms have been stored in a blue-detuned dipole trap based on sheets of argon ion laser light which support against gravity, resulting in a large reduction in the perturbation of the atomic levels due to the trapping potential.
Abstract: Sodium atoms have been stored in a blue-detuned dipole trap based on sheets of argon ion laser light which support against gravity. In this trap, the atoms spend most of their time in free fall, resulting in a large reduction in the perturbation of the atomic levels due to the trapping potential. This reduction enabled us to probe the ground state hyperfine splitting with a measurement time of 4 s, yielding a linewidth of 0.125 Hz and a Ramsey fringe contrast of 43%. The coherence time was $\ensuremath{\sim}$300 times longer than achieved in a red-detuned Nd:YAG laser dipole trap with comparable depth.
TL;DR: In this article, the widths and overall profiles of dielectric grating lines can be determined by measuring the intensity of diffracted laser light from the sample over a specified range of incident beam angles.
Abstract: The widths and overall profiles of dielectric grating lines can be determined by measuring the intensity of diffracted laser light from the sample over a specified range of incident beam angles. This technique, known as 2‐Θ scatterometry, is able to accurately and precisely measure photoresist structures in the subhalf micron regime. Moreover, a 2‐Θ scatterometer is capable of making measurements in a rapid and nondestructive manner. To test this technique we measured five identically processed wafers with nominal 0.5 μm line/0.5 μm space grating patterns. Each wafer comprised gratings in a Shipley 89131 negative photoresist exposed in a matrix of incremental exposure doses and focus settings. The scatterometry results were consistent with cross‐sectional and top‐down scanning electron microscopy (SEM) measurements of the same structures. The average deviation of 11 scatterometer linewidth measurements from top‐down SEM measurements, over a broad exposure range, is 14.5 nm. In addition, the repeatability (1σ) of the 2‐Θ scatterometer is shown to be excellent: 0.5 nm for consecutive measurements and 0.8 nm for day‐to‐day measurements.
Book•
01 Jan 1995
TL;DR: In this article, the authors present a survey of external-cavity laser designs and their applications in tunable laser spectroscopy, focusing on the use of CO2 Isotope Lasers outside their fundamental 8.9-to 12.4-m Wavelength range.
Abstract: F. J. Duarte, Introduction: Tunable Laser Complementarity. Goal of This Book. F. J. Duarte, Narrow-Linewidth Oscillators and Intracavity Dispersion: Dispersive Oscillator Configurations. Physical Dimensions. Generalized Interference Equation. Dispersion Linewidth Equation. Beam Divergence. Intracavity Dispersion. Intracavity Multiple-Prism Dispersion and Pulse Compression. Transmission Efficiency of Multiple-Prism Arrays. Wavelength Tuning. Appendix: Dispersion of Multiple-Prism Arrays and 4 x 4 Transfer Matrices. R. C. Sze and D.G. Harris, Tunable Excimer Lasers: Excimer Active Media. Tuning of Discharge and Electron Beam Pumped Excimer Lasers. Discharge Excimer Lasers. Charles Freed,CO2 Isotope Lasers and Their Applications in Tunable Laser Spectroscopy: Vibrational Energy-Level Structive of the CO2 Molecule. Rotational Energy-Level Substructure of the CO2 Molecule. Processes Governing the Excitation of Regular BandLaser Transitions in CO2. Additional Characteristics of Regular Band CO2 Lasers Transitions. Lineshape Functions and Broadening Due to Gas Pressure and Doppler Shift in CO2 Gas. Spectral Purity and Short-Term Stability. Long-Term Line-Center Stabilization of CO2 Lasers. Absolute Frequencies of Regular Band Lasing Transitions in Nine CO2 Isotopic Species. Pressure Shifts in Line-Center-Stabilized CO2 Lasers. Small-Signal Gain and Saturation Intensity of Regular Band Lasing Transitions in Sealed-off CO2 Isotope Lasers. Laser Design. Spanning the Frequency Range between Line-Center Stabilized CO2 Laser Transitions. Spectroscopic Use of CO2 Lasers outside Their Fundamental 8.9- to 12.4-(m Wavelength Range. F. J. Duarte, Dye Lasers: Laser-Pumped Pulsed Dye Lasers. Flashlamp-Pumped Dye Lasers. cw Laser-Pumped Dye Lasers. Appendix of Laser Dyes. Norman P. Barnes, Transition Metal Solid-State Lasers: Transition Metal and Lanthanide Series Lasers. Physics of Transition Metal Lasers. Cr:AlO3. Cr:BeAl2O3 Ti:Al2O3. Cr:LiCaAIF6 and Cr:LiSrAlF6. Cr:GSGG, Cr:YSAG, and Cr:GSAG. Co:MgF2, Ni:MgF2, and V:MgF2. Wavelength Control Methods. Norman P. Barnes, Optical Parametric Oscillators: Parametric Interactions. Parametric Oscillation. Spectral bandwidth and Acceptance Angles. Birefringence Effects. Average Power Limitations. Nonlinear Crystals. Phase-Matching Calculations. Performance. Tuning. Paul Zorabedian, Tunable External-Cavity Semiconductor Lasers: Semiconductor Optical Gain Media. Classes of External-Cavity Lasers. First-Order Properties. Feedback Model. External-Cavity Design. Cavity Components. Survey of External-Cavity laser Designs. Mode Selectivity of Grating Cavities. Phase-Continuous Tuning. Characterization Methods for External-Cavity Lasers. Measurement of Facet and External-Cavity Reflectances. Multimode Suppression. Multiple-Wavelength Operation. Wavelength Stabilization. Advanced Modeling Topics. Construction and Packaging. Applications. Stephen Vincent Benson, Tunable Free-Electron Lasers: Methods of Wavelength Tuning. Broadly Tunable Optical Cavities. Wiggler Considerations. Tunable Laser Facilities and Their Characteristics. Summary. References. Subject Index. F. J. Duarte, Introduction. F. J. Duarte, Narrow-Linewidth Oscillators and Intracavity Dispersion. R. C. Sze and D.G. Harris, Tunable Excimer Lasers. Charles Freed, CO2 Isotope Lasers and Their Applications in Tunable Laser Spectroscopy. F. J. Duarte, Dye Lasers. Norman P. Barnes, Transition Metal Solid-State Lasers. Norman P. Barnes, Optical Parametric Oscillators. Paul Zorabedian, Tunable External-Cavity Semiconductor Lasers. Stephen Vincent Benson, Tunable Free-Electron Lasers. References. Subject Index.
TL;DR: In this article, a spatial correlation model was used to analyze the linewidth of the Raman peaks of RuO 2 thin films in annealing at high and low temperatures.
TL;DR: The experimental realisation of a 10cm long 1.55µm Er3+-doped DFB fiber laser with a permanent phase shift incorporated into the fiber grating during writing was reported in this paper.
Abstract: The authors report the experimental realisation of a 10cm long 1.55µm Er3+-doped DFB fibre laser, with a permanent phase shift incorporated into the fibre grating during writing. Output powers of 1mW and an optical linewidth of 13kHz are observed.
TL;DR: In this paper, an Er/sup 3+/-doped distributed feedback fiber laser based on a 36 mm long Bragg grating with a permanently induced /spl pi/2 phaseshift was reported.
Abstract: Robust singlemode operation is reported of an Er/sup 3+/-doped distributed feedback fibre laser based on a 36 mm long Bragg grating with a permanently induced /spl pi//2 phaseshift. The laser is integrated into a master-oscillator/parametric-amplifier configuration, which yields an output power of 5.4 mW and has a linewidth of 15 kHz.<
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TL;DR: In this paper, a detailed kinetic study of the C49 to C54 phase transformation in TiSi2 thin films was performed, to obtain the full time, temperature, and linewidth dependence of the fraction transformed during rapid thermal annealing on patterned deep sub-micron lines.
Abstract: A detailed kinetic study of the C49 to C54 phase transformation in TiSi2 thin films was performed, to obtain the full time, temperature, and linewidth dependence of the fraction transformed during rapid thermal annealing on patterned deep‐sub‐micron lines. A Johnson–Mehl–Avrami kinetic analysis showed Avrami exponents of 0.8±0.2 for all submicron lines and 1.9±0.2 for a 40 μm side square structure. The activation energy of 3.9 eV was independent of linewidth. Transformation times increased dramatically as linewidth decreased. A kinetic model based on the density of nucleation sites as a function of linewidth and C49 grain size is proposed and shown to fit the data.
TL;DR: A single-cavity solid-state laser that is resonant with sodium D(2) absorption is reported and is sufficient to provide a time-averaged linewidth of 1.7 GHz at 589 nm.
Abstract: A single-cavity solid-state laser that is resonant with sodium D2 absorption is reported. Simultaneous 1.06- and 1.32-μm emission from a Q-switched Nd:YAG laser is summed with an intracavity type II KTP crystal. A single-intracavity etalon is sufficient to provide a time-averaged linewidth of 1.7 GHz at 589 nm.
TL;DR: It is shown that, contrary to common wisdom, the maximum gain mode of semiconductor lasers subject to optical feedback is always stable and the minimum linewidth mode is shown to be subject to a Hopf bifurcation associated with destabilizing the relaxation oscillations.
Abstract: We show that, contrary to common wisdom, the maximum gain mode of semiconductor lasers subject to optical feedback is always stable. The minimum linewidth mode is shown to be subject to a Hopf bifurcation associated with destabilizing the relaxation oscillations. This explains the experimental observation of narrow-linewidth, single-mode diode lasers operating with high optical feedback. © 1995 The American Physical Society.
TL;DR: A new ring-down technique that does not require a shutter to turn a probe laser on and off is developed that can measure a simple exponential cavity decay from which a cavity finesse can be found.
Abstract: We have developed a new ring-down technique that does not require a shutter to turn a probe laser on and off. With a rapid cavity scan we can measure a simple exponential cavity decay from which a cavity finesse can be found. When the cavity is scanned slowly, the cavity decay exhibits an amplitude modulation, and an analytic expression is derived for this modulation. With this new technique we measured the ultraslow relative velocity of the mirrors (of the order of micrometers per second) as well as the linewidth (~100 kHz) of the probe laser.
TL;DR: In this paper, the authors used the Hakki-Paoli method to extract the gain and refractive index spectra of an amplified spontaneous emission spectroscopy (SSE) system.
Abstract: Amplified spontaneous emission spectroscopy is used to extract the gain and refractive index spectra systematically. We obtain the gain and differential gain spectra using the Hakki-Paoli method. The refractive index profile, the induced change in refractive index by an incremental current, and the linewidth enhancement factor are measured from the Fabry-Perot peaks and the current-induced peak shifts in the amplified spontaneous emission spectra. The measured optical gain and refractive index are then compared with our theoretical model for strained quantum-well lasers. We show that a complete theoretical model for calculating the electronic band structure, the optical constant, and the linewidth enhancement factor agrees very well with the experiment. Our approach demonstrates that amplified spontaneous emission spectroscopy can be a good diagnostic tool to characterize laser diodes, extract the optical gain and index profiles, and confirm material parameters such as the strained quantum-well band structure parameters for a semiconductor structure under carrier injection.
TL;DR: In this paper, an absolute interferometrical distance measurement technique using a tunable semiconductor laser which, by virtue of its external cavity, has extremely small linewidth and, therefore, considerable coherence length, is discussed.
TL;DR: In this article, the transformation of titanium silicide from the C49 to the C54 structure was studied using x-ray diffraction of samples containing arrays of narrow lines of preformed C49 TiSi2.
Abstract: The transformation of titanium silicide from the C49 to the C54 structure was studied using x‐ray diffraction of samples containing arrays of narrow lines of preformed C49 TiSi2. Using a synchrotron x‐ray source, diffraction patterns were collected at 1.5–2 °C intervals during sample heating at rates of 3 or 20 °C/s to temperatures of 1000–1100 °C. The results show a monotonic increase in the C54 transition temperature by as much as 180 °C with a decreasing linewidth from 1.0 to 0.1 μm. Also observed is a monotonic increase in (040) preferred orientation of the C54 phase with decreasing linewidth. The results demonstrate the power of in situ x‐ray diffraction of narrow line arrays as a tool to study finite size effects in thin‐film reactions.
TL;DR: It is demonstrated experimentally that the intensity noise of so-called “free-running single-mode” laser diodes results from a cancellation between very large anticorrelated fluctuations of the main mode and of many weak longitudinal side modes.
Abstract: We demonstrate experimentally that the intensity noise of so-called "free-running single-mode" laser diodes results from a cancellation between very large anticorrelated fluctuations of the main mode, on one hand, and of many weak longitudinal side modes, on the other hand. When line narrowing techniques are used, intensity squeezing can be observed at room temperature, but this noise reduction is not always single-mode squeezing. These experimental results are in agreement with a simple phenomenological model using Langevin-type equations.
TL;DR: In this paper, the lasing characteristics and dynamic properties of partly gain-coupled 1.55/spl mu/m DFB lasers with a gain corrugation in the strained-layer MQW active region are presented.
Abstract: The lasing characteristics and dynamic properties of partly gain-coupled 1.55-/spl mu/m DFB lasers with a gain corrugation in the strained-layer MQW active region are presented. Narrow spectral linewidth, which is associated with the low linewidth enhancement factor, was experimentally measured. By analyzing data from RIN measurements, the damping rate, the damping factor, the intrinsic bandwidth and the effective differential gain were obtained. From the small-signal frequency response, a measured 3 dB bandwidth of 22 GHz at 10 mW output power was achieved. The high bandwidth is believed to be related to the high differential gain, resulting from the combination of longitudinal gain and index-coupling mechanisms and the reduction of the carrier transport time, which is due to an efficient lateral carrier injection along the longitudinal interface. Experimental results show that under 10 Gbit/s pseudorandom NRZ modulation, the devices have small wavelength chirp and clear eye openings making them suitable for long haul and high bit-rate applications. >
TL;DR: In this paper, a dual-mode long-cavity multisection DFB laser is driven at a subharmonic of the free-running-mode beat signal frequency to produce phase-locked millimetre waves with a 3 dB linewidth of less than 10 Hz and a 3dB locking range of ~500 MHz.
Abstract: The authors demonstrate the optical generation of extremely narrow linewidth millimetre-wave signals between 40 and 60 GHz using a single-chip semiconductor laser. A dual-mode long-cavity multisection DFB semiconductor laser is driven at a subharmonic of the free-running-mode beat signal frequency to produce phase-locked millimetre waves with a 3 dB linewidth of less than 10 Hz and a 3 dB locking range of ~500 MHz.
TL;DR: In this paper, a CdHgTe resonant cavity light emitting diode is proposed as a new infrared emitter, which consists of a bottom Bragg reflector of 86% reflectivity, a half-wavelength cavity, n doped at the beginning (1018 cm−3) and p doped in the end (1.8 cm −3), containing an active layer at the antinode position, and a top gold mirror of 95% reflectivities which also serves as an Ohmic contact.
Abstract: A CdHgTe resonant cavity light emitting diode is proposed as a new infrared emitter. The device consists of a bottom Bragg reflector of 86% reflectivity, a half‐wavelength cavity, n doped at the beginning (1018 cm−3) and p doped at the end (1018 cm−3), containing an active layer at the antinode position, and a top gold mirror of 95% reflectivity which also serves as an Ohmic contact. The emission spectrum shows a narrow peak of 8 meV full width at half‐maximum (FWHM) at 300 K, which is much less than the inhomogeneous linewidth of CdHgTe quantum wells (QWs). This electroluminescent peak matches very well the cavity resonance wavelength and FWHM, as given by transmission measurements of the unbiased cavity. The directivity is also improved by the cavity effect. Thus, we have demonstrated that even a relatively low Q microcavity can greatly enhance the characteristics of an infrared emitter in the 2–5 μm range.
TL;DR: In this paper, a new set of generalized macroscopic Maxwell-Bloch equations for semiconductor lasers is presented, which can be used to study ultrafast phenomena at femtosecond time scales where the conventional rate equations are no longer valid.