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Showing papers on "Laser linewidth published in 1970"


Journal ArticleDOI
R. Smith1
TL;DR: In this article, an analysis of optical second-harmonic generation internal to the laser cavity is presented, and it is shown that the maximum secondharmonic power generated in this way is equal to the maximum fundamental power available from the laser.
Abstract: An analysis of optical second-harmonic generation internal to the laser cavity is presented. It is shown that the maximum second-harmonic power generated in this way is equal to the maximum fundamental power available from the laser. Further, it is found that there exists a value of nonlinearity that optimally couples the harmonic out for all power levels of the laser. The magnitude of the nonlinearity required for optimum coupling is shown to be proportional to the linear losses at the fundamental and inversely proportional to the saturation parameter for the laser transition. For the YAlG:Nd laser at 1.06 μ using Ba 2 NaNb 5 O 15 as the nonlinear material, the required crystal length for optimum coupling is given by l\min{c}\max{2}(cm)\simeq 2.7 \times 10^{2}L/f where L is the linear round-trip loss and f is the ratio of the fundamental power density in the nonlinear crystal to that in the laser medium. For low-loss cavities, optimum coupling can thus be achieved for crystal lengths of 1 cm or less. The use of a mirror or mirrors within the cavity, reflecting at the harmonic, is considered as a means to couple out the total harmonic in one direction. Considerations of temperature stability and the finite oscillating linewidth of the laser are shown to favor a configuration with a single harmonic mirror located on the same surface as the fundamental mirror.

247 citations


Journal ArticleDOI
TL;DR: In this paper, a laser amplifier consisting of an ensemble of atoms, three energy levels of which form two coupled transitions of arbitrary frequencies, is treated, and the gain profile (or spontaneous emission) on the transition corresponding to the weak probe wave, modified by the perturbing field on the other transition, is calculated via a susceptibility.
Abstract: A laser amplifier to be treated in this work consists of an ensemble of atoms three energy levels of which form two coupled transitions of arbitrary frequencies. Two classical monochromatic travelling light waves are to be close to resonance with the transitions. The gain profile (or spontaneous emission) on the transition corresponding to the weak “probe” wave, modified by the perturbing field on the other transition, is calculated via a susceptibility. Within this framework, the atoms are described by an ensemble-averaged density matrix with full account of level degeneracies, light polarizations, and inelastic and dephasing collisions; an extension to elastic collisions and disorientation is straightforward. An integration over the thermal velocity distribution gives results applicable to gas discharges: directionally anisotropic narrow structures superimposed on the Doppler-broadened probe-gain profile due to non-linear interference effects in addition to saturation. At alower probe frequency, a peculiar non-Lorentzian signal appears even with transparency on the perturbing transition. At low intensities a distinction is reasonable of frequency correlations due to generalized two-quantum processes, and of a dynamic Stark splitting. These effects permit an information on the linewidth of the third forbidden transition. The connection with numerous related approaches is pointed out.

207 citations


Journal ArticleDOI
TL;DR: In this paper, a current tunable Pb0.88Sn0.12 Te diode laser was used to obtain the absorption spectrum of SF6 near the P(16 and P(20) CO2 laser lines at 10.6μm by both direct and heterodyne techniques.
Abstract: A current‐tunable Pb0.88Sn0.12 Te diode laser was used to obtain the absorption spectrum of SF6 near the P(16) and P(20) CO2 laser lines at 10.6μm by both direct and heterodyne techniques. Because of its narrow linewidth, the diode laser can perform high‐resolution spectroscopy beyond the limits of conventional instruments moreover, its infrared frequency can be tuned continuously over a range much greater than attainable with a gas laser.

161 citations


Journal ArticleDOI
TL;DR: In this paper, the authors measured the spontaneous Raman effect in the optical mode of silicon at 77 K using a continuous laser (Nd in yttrium aluminum garnet) operating at 1.064 µm.
Abstract: The absolute spontaneous-Raman-scattering efficiency and linewidth of the 521-${\mathrm{cm}}^{\ensuremath{-}1}$ optical mode of silicon have been measured at 77 K using a continuous laser (Nd in yttrium aluminum garnet) operating at 1.064 \ensuremath{\mu}m. The measured scattering efficiency (5.1 \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}6}$/cm sr for unpolarized forward scattering along the crystal [111] direction) and narrow linewidth yield a calculated value of the stimulated Raman gain coefficient which is considerably larger than those reported for other media, both solid and liquid. Stimulated Raman scattering in Si at 77 K has also been observed using a focused multimode $Q$-switched YAG: Nd laser. Inaccuracy in the measured stimulated gain resulted mainly from the uncertainty in the effective focal volume inside the silicon. Multiphoton absorption at the incident laser frequency has been considered and found to modify the measured stimulated gain by a significant amount. The estimated gain from the stimulated Raman effect was found to be in satisfactory agreement with that calculated from the absolute spontaneous-Raman-scattering efficiency.

91 citations


Journal ArticleDOI
TL;DR: In this article, a tunable dye laser with narrow-banded spectral output in the order of 0.01 A or smaller is described, which is obtained by means of a birefringent filter (Lyot filter) which was inserted into the laser cavity.
Abstract: A tunable dye laser with narrow‐banded spectral output in the order of 0.01 A or smaller is described. This narrow spectral output is obtained by means of a birefringent filter (Lyot filter) which was inserted into the laser cavity. The properties of this laser setup have been investigated and are described.

87 citations


Journal ArticleDOI
TL;DR: In this paper, photoexcited "hot" LO phonons were observed in GaAs and an order of magnitude estimate of LO phonon lifetime was obtained, which is consistent with the estimate from the linewidth in Raman scattering.

85 citations


Journal ArticleDOI
TL;DR: An external cavity coupled to a conventional Fabry-Perot GaAs diode laser operating continuously has been found to cause modulation of the light output at a frequency within the range 05 to several GHz.
Abstract: An external cavity coupled to a conventional Fabry-Perot GaAs diode laser operating continuously has been found to cause modulation of the light output at a frequency within the range 05 to several GHz The modulation depth is close to 100 percent and the linewidth can be made as narrow as 180 kHz The modulation is thought to be stimulated by the intensity noise fluctuations, which peak at the well-known spiking frequency f r The oscillations are strongly enhanced by a frequency locking action of the external cavity, being efficient when the external cavity round-trip time 2L/c , or a multiple thereof, corresponds to the inverse of the spiking frequency Since the latter is dependent on both pump current and temperature, the system can simply be tuned by adjusting the pump current For a fixed resonator length, the narrow-band oscillations occur in a small current range, in which an increase in frequency with increasing current at a rate of 400 kHz/mA is observed A small-signal analysis based on simple rate equations shows the influence of the external cavity on the intrinsic resonance frequency f r It demonstrates that self-modulation can only occur for small values of the coupling coefficient e between the laser diode and the external cavity

83 citations


Journal ArticleDOI
TL;DR: In this article, the homogeneous function which appears in the dynamical scaling expression for the linewidth of critical fluctuations in ferromagnetic and antiferromagnets was calculated.
Abstract: Starting from the kinetic equations obeyed by the time-dependent spin-correlation functions, we have calculated the homogeneous function which appears in the dynamical scaling expression for the linewidth of critical fluctuations in ferromagnets and antiferromagnets. In agreement with recent experimental findings, this function shows a minimum for κq inverse correlation length/wavenumber 0. © 1970 The American Physical Society.

81 citations


Book ChapterDOI
01 Jan 1970

53 citations


Journal ArticleDOI
TL;DR: The principles of use of gratings as laser wavelength-selective end reflectors are reviewed and a useful output beam can be derived from a grating's zeroth-order reflection.
Abstract: The principles of use of gratings as laser wavelength-selective end reflectors are reviewed A useful output beam can be derived from a grating's zeroth-order reflection This beam moves when the grating is rotated to select various laser wavelengths, but can be made stationary by the addition of auxiliary mirrors The grating-mirror combination has been applied to a CO(2) laser in the in and to a dye laser in the visible

44 citations


Journal ArticleDOI
TL;DR: A symmetrical method of optical heterodyning of the doppler shifted signal has been developed possessing minimal instrumental spectral broadening and high SNR, which can be gainfully employed in measuringurbulence structure using a cw laser.
Abstract: A symmetrical method of optical heterodyning of the doppler shifted signal has been developed possessing minimal instrumental spectral broadening and high SNR. These advantages can be gainfully employed in measuring turbulence structure using a cw laser. The method employs two beams incident on the moving scatterer. The doppler signal frequency is independent of the scattering angle and the signal possesses no receiving aperture broadening. Typical values of signal-to-noise ratio are around 30 dB for a signal strength of 3 × 10−9 W. Optical alignment is simple. Relative merits of this technique compared to the local oscillator heterodyning method are briefly described.

Journal ArticleDOI
TL;DR: In this article, the temperature dependence of the optical phonon frequencies in ZnSe and ZnTe and the L.O. phonon linewidth was measured in the temperature region from 340°K to 2°K.

Journal ArticleDOI
TL;DR: In this article, it was shown that at low temperatures the electron resonance spectrum of manganous ions dissolved in methanol exhibits an unexpected and unusual dependence on the nuclear quantum number.


Journal ArticleDOI
TL;DR: In this paper, a comparison with computer simulated spectra is used to determine hyperfine coupling constants and linewidths of poorly resolved EPR spectra of bridged Ti III -Al complexes.

Journal ArticleDOI
TL;DR: In this article, it was shown experimentally and theoretically that beam-foil spectral linewidths due to scattering of the ion beam in carbon exciter foils are of the order of 1-2 A for typical ion energies in the visible spectrum.


Journal ArticleDOI
TL;DR: The electron paramagnetic resonance linewidth and the resonance field of the single absorption line of CuCl2.2H2O was studied in this paper, where it was found that the width of the line increases slightly, down to 4.8 K.

Journal ArticleDOI
TL;DR: In this article, the authors observed selfmode-locked pulses with a rotating-mirror Q-switched CO2 laser and reported pulses as short as 10 nsec, narrower than the normal CO2 linewidth limit.
Abstract: Observation of self‐mode‐locked pulses with a rotating‐mirror Q‐switched CO2 laser is reported. Pulses as short as 10 nsec, narrower than the normal CO2 linewidth limit, were obtained. The shortness of these pulses is attributed to saturation broadening of the pulse spectrum.

Journal ArticleDOI
TL;DR: In this article, the intrinsic relaxation frequency in pure Ni is independent of temperature and that one must look for some other mechanism to account for the linewidth enhancement in pure NI.

Journal ArticleDOI
TL;DR: In this paper, the results of careful measurements of the effective porosity P eff and linewidth ΔH of single crystals of Y 3 Mn X Fe 5−x O 12 indicate that the porosity contribution to the linwidth may be represented by 0.64 (4τM)p eff.


Journal ArticleDOI
TL;DR: In this paper, a K-band saturation effect spectrometer was designed for the detection of resonance absorption in gas phase microwave spectroscopy, which exploits the nonlinear response of a balanced bridge to the amplitude modulation of a saturating microwave field.
Abstract: This paper analyzes and describes a K‐band saturation effect spectrometer designed for the detection of resonance absorption in gas phase microwave spectroscopy. As a means of obtaining molecular information, this spectrometer exploits the nonlinear response of a balanced bridge to the amplitude modulation of a saturating microwave field. To enhance saturation the sample cell terminating the signal arm of the bridge is in the form of a high‐Q cavity consisting of a half‐symmetric confocal resonator excited in the fundamental TEM00q (q≃50) mode. Microwave detection is accomplished with a sensitive superheterodyne technique using phase coherent 30 MHz intermediate frequency (i.f.) conversion. By combining the double feature of in‐phase and quadrature‐phase i.f. demodulation, this system provides means for a fully automatic bridge balance giving rise to a detected molecular signal which depends on absorption only. The theory implied in the interpretation of this signal as a function of the unsaturated absorption coefficient of the gas is worked out and the techniques relevant to the construction and operation of the instrument are presented in detail. New and potentially useful methods of using the spectrometer for the precise determination of linewidth and absolute intensity of spectral lines are outlined. The capabilities of the methods have been tested on selected lines of the molecules OCS, C2H4O, and CH3OH and the resulting data have shown that a measurement accuracy on the order of a few percent can be achieved for both linewidth and intensity.

Journal ArticleDOI
TL;DR: In this paper, the authors extended the linewidth-lifetime relation of the weisskopf-wigner relation to systems with an arbitrary number of ionic energy levels.
Abstract: The earlier work on harmonic raman ion-lattice interaction processes is extended to systems with an arbitrary number of ionic energy levels. The weisskopf-wigner linewidth-lifetime relation (that the full width is the sum of the inverse lifetimes of the two states) is valid only for those linewidth contributions arising from raman processes in which there is a net electronic transition, that is, processes which contribute to depopulation rates. This includes the usual three level raman processes and the semidiagonal process, but not the self energy raman process; for the latter process, transition probability amplitudes combine coherently.


Journal ArticleDOI
TL;DR: In this article, the linewidth of the transition from the 5D0 state to the crystal field states of the 7Fi levels has been measured at 4.2 and 300 °K.
Abstract: The lineshift and the linewidth of the transition5D0 →7F0 has been measured in EuCl3 · 6H2O, Eu(NO3) · 6H2O and Eu2O3 as a function of temperature between 4.2 and 300 °K. In all cases the lines are shifted to the blue (shorter wavelength) with increasing temperature. A linear relationship is found between the lineshifts and the internal energies of the compounds.—In Eu(C2H5SO4)3 · 9H2O the linewidth of several transitions from the5D0 state to the crystal field states of the7Fi levels have been measured at 4.2 °K. The linewidths are compared with those expected for a depopulation of the7Fi states by phonons.

Journal ArticleDOI
TL;DR: In this paper, the linewidth of the very sharp zero phonon line has been studied and two types of coupling of the electron to the lattice are considered, i.e., a strong coupling, which causes lattice relaxation and a weaker coupling to the excition transfer matrix element, which leads to phonon scattering processes within the exciton band.

Journal ArticleDOI
TL;DR: In this paper, an N2O laser is described which is tunable over 65 rotational lines of the 00°1-10°0 band of CO2 and a simple method is used to determine the cavity losses of this laser.
Abstract: An N2O laser is described which is tunable over 65 rotational lines of the 00°1–10°0 band A simple method is used to determine the cavity losses of this laser Absorption of a number of N2O lines by the 00°1–10°0 band of CO2 is demonstrated The P (20) line of N2O is observed after attenuation by a long path of N2O at 125-torr pressure and the peak absorption coefficient for this line is found to be 00094 cm−1 at 300 K The N2O laser has a certain advantage over the CO2 laser for long-range communications through the atmosphere