Showing papers on "Laser linewidth published in 1984"
TL;DR: In this article, the authors discuss mutual phase locking of Josephson oscillations in an array of junction junctions, based on a free perturbative solution of the resistively shunted junction model.
258 citations
TL;DR: In this paper, the effect of external optical feedback on the linewidth of a single-mode injection laser is considered theoretically, and a set of three rate equations with Langevin noise sources is used to obtain the power spectrum.
Abstract: The effect of external optical feedback on the linewidth of a single-mode injection laser is considered theoretically. A set of three rate equations with Langevin noise sources is used to obtain the power spectrum. If the high-frequency structure in the power spectrum is ignored, the line shape is Lorentzian and exhibits broadening or narrowing depending on the external-cavity phase shift. Particular attention is paid to the line narrowing after including the effect of carrrier-induced index changes.
240 citations
TL;DR: In this article, a detailed theoretical analysis of stability for a semiconductor laser in an external cavity is presented, where the limits of stable operation are determined as a function of the external cavity parameters and the linewidth enhancement factor α.
Abstract: A detailed theoretical analysis of stability is presented for a semiconductor laser in an external cavity. The limits of stable operation are determined as a function of the external cavity parameters and the linewidth enhancement factor α. Instability is related to jumps of the laser frequency between external cavity modes (frequency bistability) or to feedback-induced intensity pulsations due to the carrier density dependence of the refractive index. The limit of bistability is derived from the steady-state solutions of the rate equations and the intensity pulsation limit is obtained from a small-signal analysis. This analysis also gives the location of zeros in the system determinant and the resulting FM noise spectrum. For practical applications we emphasize the determination of the stable tuning range for the phase in the external cavity and the classification of the possible types of instability for various feedback levels.
226 citations
TL;DR: The standard approach for including laser line-shape effects in calculated coherent anti-Stokes Raman spectra is shown to be incorrect and a closed-form solution for the special case of Lorentzian laser line shapes is presented.
Abstract: The standard approach for including laser line-shape effects in calculated coherent anti-Stokes Raman spectra is shown to be incorrect. The correct approach involves extra terms that become important if the laser linewidth is larger than the Raman linewidths. The standard approach can lead to errors in measurements of concentration or nonresonant susceptibility. A closed-form solution for the special case of Lorentzian laser line shapes is presented. Measurements using broadband and narrow-band lasers support the modified theory but are inconsistent with the standard theory.
109 citations
TL;DR: In this paper, the changes in the linewidth and line asymmetry can be interpreted in terms of the final state effects, i.e., the response of the valence electrons to the core-hole as a function of the cluster size.
104 citations
TL;DR: In this article, an expression for the excitonic photoluminescence linewidth in intentionally undoped semiconductor alloys is derived and the dominant mechanism for the line broadening is due to the statistical potential fluctuations caused by the components of the alloy.
Abstract: An expression for the excitonic photoluminescence linewidth in intentionally undoped semiconductor alloys is derived. The dominant mechanism for the line broadening is due to the statistical potential fluctuations caused by the components of the alloy. These fluctuations are accounted for by using statistical arguments developed by Lifshitz and then related to the linewidth. Compositional dependence of the linewidth is derived. It is shown that the linewidth is strongly dependent on the short range disorder present in the alloy. The theoretical results are compared with the available low‐temperature photoluminescence data in GaAlAs.
97 citations
TL;DR: Design and operating characteristics are reported for high prf copper laser-pumped rhodamine 590 dye-laser oscillators using simple Littrow-mounted or grazing-incidence grating cavities incorporating double-prism beam expanders.
Abstract: Design and operating characteristics are reported for high prf copper laser-pumped rhodamine 590 dye-laser oscillators using simple Littrow-mounted or grazing-incidence grating cavities incorporating double-prism beam expanders. Conversion efficiencies from the 2-W, λ510.6-nm pump beam at the λ575-nm peak of the dye tuning band are 4–5% for linewidths in the subgigahertz range down to 650 MHz at a pulse repetition frequency of 8 kHz. Background amplified spontaneous emission intensity is low, typically 1% of tunable laser intensity for the Littrow-grating cavity and only 0.1% for the grazing-incidence grating cavity.
89 citations
TL;DR: In this article, the reduction of frequency chirping and dynamic spectral linewidth in high-speed directly modulated semiconductor lasers, by external injection from a CW single-mode laser, was reported.
Abstract: We report the reduction of frequency chirping and dynamic spectral linewidth in high-speed directly modulated semiconductor lasers, by external injection from a CW single-mode laser. Reduction by more than a factor of 2 in chirped line-width was obtained in a GaAlAs laser modulated with a 1 GHz, 100 Ps current pulses.
67 citations
TL;DR: Ferrimagnetic resonance (FMR) measurements were made at room temperature on polished spheres of about 0.3 mm size at frequencies between 3 GHz and 90 GHz as discussed by the authors, and the observed FMR linewidth ΔH can be described by a frequency independent two-magnon scattering contribution ranging between 5 Oe and 10 Oe.
62 citations
TL;DR: In this article, a long-pulse, electric-discharge xenon chloride laser with intracavity Fabry-Perot etalons was used for multipass operation.
Abstract: A spectral linewidth of less than 70 fm and diffraction-limited beam divergence have been obtained from a long-pulse, electric-discharge xenon chloride laser with intracavity Fabry-Perot etalons. A gain duration of 100 ns provided for multipass operation of the etalons, significantly improving both contrast and finesse. The electrical-discharge circuit required to produce this long gain duration was comprised of a pulse-forming network, a saturable-inductor magnetic switch, and a tapered constant-impedance interface transmission line.
51 citations
TL;DR: Simple expressions for the halfwidth and finesse of a Fabry-Perot interferometer fringe broadened by defects have good accuracy for most practical forms of defect and are applicable to mirror surface defects, parallelism errors, angular dispersion of illumination, finite spectral linewidth, and fluctuations in interferometers spacing.
Abstract: Simple expressions are given for the halfwidth and finesse of a Fabry-Perot interferometer fringe broadened by defects. The expressions are unrestricted as to defect magnitude and have good accuracy for most practical forms of defect. The results are applicable to mirror surface defects, parallelism errors, angular dispersion of illumination, finite spectral linewidth, and fluctuations in interferometer spacing as well as most combinations of two or more types of broadening defect. An experimental investigation of broadening due to parallelism errors confirms the theory.
TL;DR: In this article, a small current step in the leading edge of the drive pulse was proposed to reduce the carrier density oscillations and frequency chirping of single frequency semiconductor lasers. But the performance of the modified current pulse was limited.
Abstract: Carrier density oscillations and frequency chirping of pulse code modulated single frequency semiconductor lasers are shown to be greatly reduced by use of a small current step in the leading edge of the drive pulse. For a 100 km single mode fibre link the dispersion power penalty at 1.55 ?m resulting from dynamic line broadening is predicted to be reduced from 3.7 to 1.0 dB by use of the modified current pulse.
TL;DR: In this paper, the resonance fluorescence of a two-level atom irradiated by a smooth pulse of hyperbolic secant shape is investigated and the authors calculate explicitly the energy spectrum of photons at t to infinity in the limit of spontaneous linewidth much smaller than the Fourier width of the pulse.
Abstract: The resonance fluorescence of a two-level atom irradiated by a smooth pulse of hyperbolic secant shape is investigated. The authors calculate explicitly the energy spectrum of photons at t to infinity in the limit of spontaneous linewidth much smaller than the Fourier width of the pulse. The spectrum is completely different from the Mollow spectrum. It is multi-peaked and the number of peaks increases with the area of the pulse.
TL;DR: In this paper, the temperature dependence of homogeneous and inhomogeneous vibrational linewidth broadening is reported for the symmetric CH3-stretching vibration in acetonitrile over its entire liquid range at P = 1 atm.
Abstract: The temperature dependence of homogeneous and inhomogeneous vibrational linewidth broadening is reported for the symmetric CH3‐stretching vibration in acetonitrile over its entire liquid range at P=1 atm. A selective excite‐and‐probe vibrational dephasing experiment based on transient stimulated Raman scattering in high laser depletion is used to measure the homogeneous dephasing times T2. The separation of homogeneous and inhomogeneous broadening processes is accomplished using the combined results of isotropic spontaneous Raman studies and selective picosecond vibrational dephasing experiments. As a function of temperature, the relative contributions of homogeneous and inhomogeneous broadening are shown to change significantly in opposing directions. Agreement between experiment and theory supports previous suggestions that homogeneous broadening is caused by rapidly varying processes which affect the vibration via short range repulsive forces. The results also suggest that inhomogeneous broadening is c...
TL;DR: In this article, the isotope shifts (IS) of 141 −144 Eu have been measured at the mass-separator output and the overall detection efficiency of Eu atoms is equal to 3 x 10 -4.
TL;DR: In this article, a method to slow down an atomic beam with a counter-propagating resonant laser beam is proposed, which allows the atoms to come to rest without the need for frequency tuning or laser chirping.
TL;DR: In this article, an improved method of calculating the linewidth of a laser oscillator due to phase noise is proposed, where the fluctuation in the output amplitude that leads to the phase diffusion is calculated as the amplified thermal and the quantum noise which are delta-correlated in time.
Abstract: An improved method of calculating the linewidth of a laser oscillator due to phase noise is proposed. The fluctuation in the output amplitude that leads to the phase diffusion is calculated as the amplified thermal and the quantum noise which are delta-correlated in time. The saturated gain distribution along the cavity axis that is consistent with the output coupling at the end surfaces is taken into account in calculating the amplification of the noises. The resulting linewidth formula differs somewhat from the conventional formula.
TL;DR: In this paper, the frequency chirp characteristics of single-longitudinal-mode semiconductor laser operating at 15 μm wavelength and subject to large signal amplitude modulation in the 50 to 800 MHz range were measured on cleaved-coupled-cavity (C3) and GRIN-rod external cavity lasers.
Abstract: We have measured the frequency chirp characteristics of single-longitudinal-mode semiconductor lasers operating at 15 μm wavelength and subject to large signal amplitude modulation in the 50 to 800 MHz range Measurements on cleaved-coupled-cavity (C3) and GRIN-rod external cavity lasers show that the wavelength chirp is large enough to cause a penalty in ultra-high-bit-rate long-haul optical-fibre systems
TL;DR: True cw laser operation was achieved with the vibronic KZnF(3):Cr(3+) laser at room temperature with a 14% power-output slope efficiency with longitudinal pumping in a folded three-mirror resonator.
Abstract: True cw laser operation was achieved with the vibronic KZnF3:Cr3+ laser at room temperature. The laser is optically pumped with a krypton laser at 647 and 676 nm. With 1 W of absorbed power the laser is tunable between 785 and 865 nm. A 14% power-output slope efficiency was observed with longitudinal pumping in a folded three-mirror resonator.
TL;DR: In this paper, the linewidth enhancement factor for an idealised GaInAs quantum-well laser was calculated and values between 1 and 2 were found for a range of possible lasing energies.
Abstract: The linewidth enhancement factor α is calculated for an idealised GaInAs quantum-well laser. Values between 1 and 2 are found for a range of possible lasing energies. Somewhat larger values are expected for GaInAs quantum wells with InP barriers. It is concluded that dramatic reductions in α are not to be expected for quantum wells.
TL;DR: In this article, the authors report measurements of EPR in the magnetic semiconductors Cd1−xMnxTe and reanalyze earlier data and find that the room temperature linewidth increases as x is increased, and the g value, obtained by reference to the zero of the derivative curve, is almost independent of x.
Abstract: We report measurements of EPR in the magnetic semiconductors Cd1−xMnxTe and reanalyze earlier data. Experimentally we find (i) the room temperature linewidth increases as x is increased, (ii) the g value, obtained by reference to the zero of the derivative curve, is almost independent of x, (iii) each resonance line has a symmetric lineshape, and (iv) for each x the linewidth increases as T is reduced. These facts suggest that the resonances are not relaxation broadened but are, instead, inhomogeneously broadened. We model this inhomogeneity in terms of a Gaussian distribution of internal fields and show that there is a sharp change in the x dependence of the corresponding Gaussian widths at the percolation threshold. We also note that the temperature dependence of the linewidths follows an empirical form proposed earlier for metallic spin glasses.
TL;DR: Systematic investigations of signal-to-noise ratios obtained in frequency-modulation (FM) spectroscopic measurements utilizing pulsed tunable dye lasers are reported which show that the noise becomes smaller as the modulation frequency is raised relative to the laser linewidth.
Abstract: Systematic investigations of signal-to-noise ratios obtained in frequency-modulation (FM) spectroscopic measurements utilizing pulsed tunable dye lasers are reported which show that the noise becomes smaller as the modulation frequency is raised relative to the laser linewidth. Thus by raising our modulation frequency and narrowing our laser linewidth, we are able to detect ~0.1% absorption in spite of ~50% shot-to-shot fluctuations in the dye laser intensity. In addition several useful aspects of FM spectroscopy using pulsed dye lasers are demonstrated. The broad tuning range, ~5 cm−1, over which continuous scans may be made is demonstrated by recording absorption spectra of I2, Br2, NO2, and Na. The sensitivity of the technique to broad absorption features is shown by absorption spectra of the above species at atmospheric pressure. The Na was in a flame showing the potential usefulness of the technique in combustion diagnostics applications. Finally the nanosecond time resolution is demonstrated by observing the absorption of a transient population in the Na 3p state which has a lifetime of 16 nsec.
TL;DR: In this paper, the decay of coherently excited longitudinal optical phonons in GaP has been observed through time delayed coherent anti-Stokes Raman scattering measurements with picosecond light pulses.
TL;DR: In this paper, the influence of field frequency fluctuations on unsaturated two-photon absorption was measured and the statistical properties of the frequency fluctuations in this experiment were carefully controlled, and the laser lineshape is nearly Lorentzian.
Abstract: In this report, I will discuss a recent experiment [1] in which we measured the influence of field frequency fluctuations on unsaturated two-photon absorption. The statistical properties of the frequency fluctuations in this experiment are carefully controlled, and the laser lineshape is nearly Lorentzian. This experiment provides direct confirmation of theoretical results of MOLLOW [2] on the linewidth of two- photon absorption by a phase-diffusing field. This report is organized as follows. The first section presents the background of the experiment, including Mollow’s results for two-photon absorption from a phase diffusing field, and a simple extension of his work to include the effect of the finite correlation time of the fluctuations. The next unit describes the manner in which the experiment was conducted, and a discussion of the results appears in the final section.
TL;DR: A complete equation is formulated that describes the spectral linewidth of a dye laser provided by the cavity of the prism–grating–mirror combination.
Abstract: A complete equation is formulated that describes the spectral linewidth of a dye laser provided by the cavity of the prism–grating–mirror combination. It is the consolidation of previously published work. Thermal stability of the dye laser frequency is also discussed.
TL;DR: In this paper, the isotropic Raman linewidth of t-butanol at 753 cm −1 has been measured in aqueous solution and in cyclohexane solution.
TL;DR: In this paper, the quantum-limit cyclotron-resonance linewidth is studied theoretically, assuming electron scattering by acoustic phonons and ionized impurities, and a minimum is predicted for the linearity as a function of magnetic field but only for a restricted range of electron and ionised-impurity densities.
Abstract: The quantum-limit cyclotron-resonance linewidth is studied theoretically, assuming electron scattering by acoustic phonons and ionized impurities. A minimum is predicted for the linewidth as a function of magnetic field but only for a restricted range of electron and ionized-impurity densities. Near this minimum the linewidth is proportional to the square root of the impurity density and is independent of temperature.
TL;DR: In this article, the authors measured the magnetostatic and dielectric resonances of samples of barium hexaferrite single crystals in the millimeter wavelength range and concluded that the contribution of the intrinsic loss to the FMR linewidth is about ten times higher than for YIG.
Abstract: Measurements are reported on the magnetostatic and dielectric resonances of samples of barium hexaferrite single crystals in the millimeter wavelength range. The behavior of these resonances versus frequency and temperature leads to the conclusion that the contribution of the intrinsic loss to the FMR linewidth is about ten times higher than for YIG.
TL;DR: In this article, the linewidth of the site selection spectra was measured with a Fabry-Perot interferometer and the temperature dependence from 1.8 to 4.2 K was found to follow a T1.25±0.2 power law.
TL;DR: Stimulated Brillouin scattering of KrF laser radiation focused in SF(6) gas at pressures of 1.4 to 9.8 atm has been studied experimentally and pulse compression up to peak intensities of two times the pump intensity has been achieved.
Abstract: Stimulated Brillouin scattering of KrF laser radiation focused in SF6 gas at pressures of 1.4 to 9.8 atm has been studied experimentally. For an input linewidth of 0.08 cm−1 and focal lengths of 1 and 2 m, reflectivities of 80% have been measured. Pulse compression up to peak intensities of two times the pump intensity has been achieved in a pulse that is partially phase conjugate to the pump pulse. At high pressures a short backward Raman spike was observed preceding the Brillouin backscattered signal.