Showing papers in "Optics Letters in 1978"
TL;DR: A digital method for solving the phase-retrieval problem of optical-coherence theory: the reconstruction of a general object from the modulus of its Fourier transform, which should be useful for obtaining high-resolution imagery from interferometer data.
Abstract: We present a digital method for solving the phase-retrieval problem of optical-coherence theory: the reconstruction of a general object from the modulus of its Fourier transform. This technique should be useful for obtaining high-resolution imagery from interferometer data.
1,762 citations
TL;DR: A form of coherent trapping that occurs when multiple resonant laser beams are used to couple the various ground states to a common upper level is described, which prevents the extraction of the entire population.
Abstract: It is often desirable in laser spectroscopy and isotope separation to extract as much as possible of an atomic or molecular population that is distributed among a number of ground-state sublevels and low-lying metastable levels. We describe a form of coherent trapping that occurs when multiple resonant laser beams are used to couple the various ground states to a common upper level. This effect prevents the extraction of the entire population. We then study the effect with two dye lasers and an atomic beam and suggest possible ways to maximize the pumping efficiency.
536 citations
TL;DR: All 16 elements of the Mueller matrix of an optical system (sample) can be encoded onto, hence can be retrieved from, a single detected signal using a class of photopolarimeters with modulated polarizing and analyzing optics.
Abstract: All 16 elements of the Mueller matrix of an optical system (sample) can be encoded onto, hence can be retrieved from, a single detected signal using a class of photopolarimeters with modulated polarizing and analyzing optics. The general theory of operation of such polarimeters is presented. We also propose a specific new photopolarimeter whose polarizing and analyzing optics are modulated by synchronously rotating two quarter-wave retarders at angular speeds ω and 5ω. When the light flux leaving such polarimeter is linearly detected, a periodic signal J=a0+∑n=112(an cos nωft+bn sin nωft) is generated, with fundamental frequency ωf = 2ω. From the Fourier amplitudes a0, an, bn, to be measured by performing a discrete Fourier transform (DFT) of the signal ℐ, the 16 elements of the Mueller matrix are simply determined.
516 citations
TL;DR: Degenerate four-wave mixing in a two-level absorbing (or amplifying) system is treated, leading to a quantitative description of amplified reflection, oscillation, and phase conjugation.
Abstract: Degenerate four-wave mixing in a two-level absorbing (or amplifying) system is treated, leading to a quantitative description of amplified reflection, oscillation, and phase conjugation.
426 citations
TL;DR: An incoherent optical data-processing method is described, which has the potential for performing discrete Fourier transforms of short length at rates far exceeding those afforded by both special-purpose digital hardware and representative coherent optical processors.
Abstract: An incoherent optical data-processing method is described, which has the potential for performing discrete Fourier transforms of short length at rates far exceeding those afforded by both special-purpose digital hardware and representative coherent optical processors.
375 citations
TL;DR: The formation and characterization of narrow-band-waveguide reflection filters in Ge-doped silica optical fibers is described, which can have complex response profiles and are tunable in frequency by mechanical strain.
Abstract: The formation and characterization of narrow-band-waveguide reflection filters in Ge-doped silica optical fibers is described. The filters can have complex response profiles and are tunable in frequency by mechanical strain.
247 citations
TL;DR: A variation of the grazing-incidence pulsed dye laser is presented that has been operated in a single longitudinal cavity mode with a single-shot linewidth of less than 300 MHz and a time-averaged linewitzer of 750 MHz.
Abstract: A variation of the grazing-incidence pulsed dye laser is presented. This laser has been operated in a single longitudinal cavity mode with a single-shot linewidth of less than 300 MHz and a time-averaged linewidth of 750 MHz. The single-mode conversion efficiency of the laser is 2% using Rhodamine 6G dye.
239 citations
TL;DR: The holographic plate corresponds to an infinite set of gated viewing systems triggered by the traversing reference beam, and scanning along the processed plate produces a continuous-motion picture of the light in flight.
Abstract: A flat object surface and a hologram plate are both illuminated at an oblique angle by laser light of short pulse duration or short coherence length Only those parts of the object surface are holographically recorded that correspond to a small-pathlength difference between object beam and reference beam The holographic plate therefore corresponds to an infinite set of gated viewing systems triggered by the traversing reference beam Scanning along the processed plate produces a continuous-motion picture of the light in flight This new technique probably represents the ultimate in high-speed photographic recording, as no mechanical or electrical inertia is involved
206 citations
TL;DR: A Type-2 scanning microscope is found to have a much reduced depth of field according to these criteria, which makes it useful for studying thick biological slices, which does not contradict the claim thatDepth of field may be much increased in such a microscope by using lenses with annular pupil functions.
Abstract: Various definitions of depth of field in the microscope are discussed. The variation in the integrated intensity in the image of a point object outside the focal plane shows how the microscope discriminates against such objects. The power diffusely scattered by a translucent object is also considered. A Type-2 scanning microscope is found to have a much reduced depth of field according to these criteria, which makes it useful for studying thick biological slices. These results do not contradict the claim that depth of field may be much increased in such a microscope by using lenses with annular pupil functions.
201 citations
TL;DR: An equivalence theorem is formulated that provides conditions under which planar sources of different states of spatial coherence will generate optical fields that have identical far-zone intensity distributions.
Abstract: An equivalence theorem is formulated that provides conditions under which planar sources of different states of spatial coherence will generate optical fields that have identical far-zone intensity distributions. As an example, a partially coherent source whose linear dimensions are large compared with the correlation length of the light across the source is described that will generate a field whose far-zone intensity distribution is identical with that of a Gaussian laser beam.
199 citations
TL;DR: This Letter is the first report of the observation of amplified reflection and self-oscillation produced by degenerate optical four-wave mixing by using a resonantly enhanced Kerr nonlinearity in atomic sodium vapor.
Abstract: This Letter is the first report of the observation of amplified reflection and self-oscillation produced by degenerate optical four-wave mixing by using a resonantly enhanced Kerr nonlinearity in atomic sodium vapor. Phase-conjugated reflected waves with intensities 100 times greater than input-signal intensities were achieved with only 40-kW/cm2 pump intensity.
TL;DR: The resulting mode dispersion in short fiber lengths from the depolarization of broad-bandwidth light is measured, in good agreement with the observed birefringence.
Abstract: In real single-mode optical fibers, imperfections cause the two possible polarizations to propagate at different phase velocities This birefringence leads to different group velocities We have measured the resulting mode dispersion in short fiber lengths (05-25 m) from the depolarization of broad-bandwidth light In a typical fiber we found 30 psec/km at 069-microm wavelength, in good agreement with the observed birefringence The effect of mode dispersion can be compensated by a +/-68 degrees double twist midway along the fiber, interchanging the fast and slow modes
TL;DR: A nonlinear optical technique is described that performs the functions of spatial correlation and convolution of spatially encoded waves by mixing spatially dependent optical fields in the Fourier-transform plane of a lens system using a degenerate four-wave mixing scheme.
Abstract: A nonlinear optical technique is described that performs, essentially instantaneously, the functions of spatial correlation and convolution of spatially encoded waves. These real-time operations are accomplished by mixing spatially dependent optical fields in the Fourier-transform plane of a lens system. The use of a degenerate four-wave mixing scheme eliminates (in the Fresnel approximation) phase-matching restrictions and (optical) frequency-scaling factors. Spatial bandwidth-gain considerations and numerical examples, as well as applications to nonlinear microscopy, are presented.
TL;DR: A laser technique for simultaneous determination of particle size and velocity is proposed and the requisite theoretical analysis presented.
Abstract: Two beams of electromagnetic radiation with symmetric radial intensity distributions are directed through space. A particle sampling volume is defined by those portions of the two beams within the field of view of one or more radiation sensitive detectors. The detectors respond to scattered radiation or fluorescence from particles passing through the beams in the sampling volume. The detector output for a single particle indicates two signal pulses corresponding to those times when the particle was in one of the beams. The speed of the particle in the plane perpendicular to the beams is determined from the transit time or width of the signal pulses, and the angle of the particle traverse in that plane determined from the time-of-flight between the signal pulses. The speed and angle thereby determine two velocity components in the perpendicular plane. Then the exact particle trajectory is specified by the angle and one point on the trajectory which is determined from relative magnitudes of the signal pulses. This allows calculation of the radiation intensity incident on the particle throughout the trajectory from known radiation beam properties. A device then responds to the signal pulses to indicate the size or other physical properities of the particle without the ambiguity present if the incident radiation intensity is unknown.
TL;DR: Quantitative measurements on the correction of severely aberrated laser beams using stimulated Brillouin scattering (SBS) at 0.69 microm are obtained and it is shown that under certain conditions SBS can be used to restore an aberrated optical beam to its original unaberrated condition.
Abstract: We have obtained quantitative measurements on the correction of severely aberrated laser beams using stimulated Brillouin scattering (SBS) at 0.69 μm. We have shown that under certain conditions SBS can be used to restore an aberrated optical beam to its original unaberrated condition. When an optical beam double passes an aberrating region after reflecting from an “ordinary” mirror (i.e., a plane mirror) the aberration is twice that obtained from a single pass. However, when the aberrated beam enters a medium that allows SBS to occur, it emerges from its second pass through the aberrating medium in the same condition as that in which it originally entered. Quantitative experiments are described in which a single-mode ruby laser beam is intentionally aberrated by passing it through an etched plate. When the beam is allowed to double-pass the plate using an ordinary reflector (i.e., plane mirror), the beam divergence is more than 10 times the diffraction-limited divergence. However, when we replace the ordinary reflector with a cell in which SBS can take place, the SBS reflected beam is restored to diffraction-limited divergence when it is allowed to pass back through the aberrating medium. Applications of this time-reversal or phase-reversal technique for correcting aberrations in optical trains and atmospheric turbulence are discussed.
TL;DR: This is the first reported demonstration of cw wavefront conjugation by degenerate four-wave mixing in a solid using a cw argon-ion laser.
Abstract: This is the first reported demonstration of cw wavefront conjugation by degenerate four-wave mixing in a solid. Conversion efficiencies of 3% for conjugate-wave generation were obtained in a ruby crystal using a cw argon-ion laser.
TL;DR: The kinetics of excited electron states and of the production of molecular and fragmented ions of some polyatomic molecules have been investigated with high temporal resolution.
Abstract: Laser spectroscopy and kinetic mass spectrometry of polyatomic isolated molecules have been carried out by using stepwise laser ionization of molecules in a mass spectrometer The optical absorption spectrum of NO(2) has been recorded, for example, by using pulsed dye-laser excitation and H(2) vacuum-ultraviolet laser ionization of molecules The kinetics of excited electron states and of the production of molecular and fragmented ions of some polyatomic molecules have been investigated with high temporal resolution The sensitivity achieved is 10(-10) cm(-1) of the absorption coefficient and 10(9) (10(5)) molecules in the ground (electronically excited) state in the irradiated volume
TL;DR: The application of low-power cw laser sources in obtaining high-resolution stimulated Raman spectra (SRS) of the Q01 transition in molecular hydrogen shows a motionally narrowed minimum linewidth of 250 ± 5 MHz.
Abstract: We report the application of low-power cw laser sources in obtaining high-resolution stimulated Raman spectra (SRS) of the Q01 (1) transition in molecular hydrogen. Fully resolved spectra of both the real and the imaginary parts of the Raman susceptibility, obtained with a resolution of <25 MHz, show a motionally narrowed minimum linewidth of 250 ± 5 MHz. The cw SRS techniques reported herein should find a variety of applications in high-resolution Raman studies.
TL;DR: It is shown that a nearly degenerate four-wave mixing process is capable of yielding a real-time optical bandpass filter that has a large field of view and is able to provide an amplified bandpass.
Abstract: It is shown that a nearly degenerate four-wave mixing process is capable of yielding a real-time optical bandpass filter. The filter has a large field of view and is capable of providing an amplified bandpass. Moreover, the conjugate nature of the output field can be utilized to increase the signal-to-noise ratio of the device. For a 1-cm interaction length in a nondispersive medium, the optical bandpass at 5000 A can be varied from ~9 GHz down to the linewidth of the exciting laser.
TL;DR: A new method using a four-layered optical waveguide consisting of both nonlinear and linear materials with normal material dispersions to realize efficient nonlinear interactions is described, which improves the conversion efficiency more than 40 times compared with the optimized conventional three-layering nonlinear waveguide.
Abstract: A new method using a four-layered optical waveguide consisting of both nonlinear and linear materials with normal material dispersions to realize efficient nonlinear interactions is described. Numerical examples and experimental results are also presented for the case of SHG in a glass–ZnS–TiO2–air waveguide with complete phase matching at the TE0 fundamental and TM1 harmonic wavelengths obtained using an optical parametric oscillator. This method improves the conversion efficiency more than 40 times compared with the optimized conventional three-layered nonlinear waveguide to TE0 fundamental and TM2 harmonic together with the thickness tolerance for the phase matching.
TL;DR: A one-step rainbow holography process, which uses the technique of aerial imaging of a lens, is presented and experimental results of both pseudoscopic and orthoscopic holographic imaging are included.
Abstract: A one-step rainbow holography process, which uses the technique of aerial imaging of a lens, is presented. Experimental results of both pseudoscopic and orthoscopic holographic imaging are included. A brief discussion of the results of this new technique is also given.
TL;DR: In this article, the B2Σ+ → X 2 Σ+ transition of HgBr was achieved by dissociating Hgbr2 vapor by electron collision in a transverse electric discharge, and the lasing wavelengths were identical with the ones previously measured by excitation through photodissociation.
Abstract: Lasing action was achieved on the B2Σ+ → X2Σ+ transition of HgBr by dissociating HgBr2 vapor by electron collision in a transverse electric discharge. The lasing wavelengths, consisting of six lines between 502 and 505 nm, are identical with the ones previously measured by excitation through photodissociation.
TL;DR: The first reported observation in the infrared of nonlinear phase-conjugated reflection is presented via degenerate four-wave mixing in polycrystalline germanium, facilitated by taking advantage of the counterpropagating waves internal to a pulsed CO2 laser cavity.
Abstract: We present the first reported observation in the infrared of nonlinear phase-conjugated reflection. This was achieved via degenerate four-wave mixing in polycrystalline germanium. The observation was facilitated by taking advantage of the counterpropagating (strong) waves internal to a pulsed CO2 laser cavity. The measured effective reflectivity was 2% with a 10-mm interaction length. This simple intracavity technique is generally applicable to any nonlinear material transparent at the wavelength of the laser into which it is inserted.
TL;DR: A cw Ni:MgF(2) solid-state laser, optically pumped by a Nd:YAG laser, has been operated in the range 1.63 to 1.75microm, and fully damped relaxation oscillations have been observed, which indicate a distributed loss coefficient of 0.003 cm(-1).
Abstract: A cw Ni:MgF(2) solid-state laser, optically pumped by a Nd:YAG laser, has been operated in the range 1.63 to 1.75microm. Under various operating conditions, output powers up to 1.7 W, power efficiencies up to 37%, and lasing at a crystal temperature of 200 K have been achieved. Fully damped relaxation oscillations have been observed, which indicate a distributed loss coefficient of 0.003 cm(-1).
TL;DR: In this article, a simple new technique for measuring absolute radiative quantum efficiencies of fluorescing ions in solids that can be applied to systems exhibiting concentration quenching of the fluorescence.
Abstract: We have developed a simple new technique for measuring absolute radiative quantum efficiencies of fluorescing ions in solids that can be applied to systems exhibiting concentration quenching of the fluorescence. The technique requires measurement of the photoacoustic signal and fluorescent lifetime as a function of ion concentration. Application of this method to the upper laser level of Nd(3+) in ED2 glass yields a value for the quantum efficiency somewhat smaller than that found in previous estimates and measurements.
TL;DR: The two-photon transition wavelengths to rubidium s levels were measured up to n = 50 with better than 1 x 10(-7) absolute accuracy and can be represented to within the experimental precision by a simple function of the principal quantum number.
Abstract: We used a tunable cw dye laser to observe Doppler-free two-photon transitions to alkali-atom Rydberg levels. Real-time signals were obtained in an ionization cell of appropriate construction. The two-photon transition wavelengths to rubidium s levels were measured up to n = 50 with better than 1 x 10(-7) absolute accuracy and can be represented to within the experimental precision by a simple function of the principal quantum number, Other related transitions and future possibilities are considered.
TL;DR: It is shown that the PDI is simple and easy to use and also yields fringes of constant optical path difference similar to those obtained with a Twyman–Green interferometer.
Abstract: A point-diffraction interferometer (PDI) for use in the infrared is discussed. It is shown that the PDI is simple and easy to use and also yields fringes of constant optical path difference similar to those obtained with a Twyman–Green interferometer. The fabrication of the PDI is described, and typical results obtained using the interferometer at a wavelength of 10.6 μm are shown.
TL;DR: Lenses made of Bragg-type gratings and used for integrated optics are fabricated by the technique of electron-beam pattern generation, chemical etching, and printing.
Abstract: Lenses made of Bragg-type gratings and used for integrated optics are fabricated by the technique of electron-beam pattern generation, chemical etching, and printing. They consist of straight lines of varying inclination and spacing. Focusing action is demonstrated experimentally.
TL;DR: The authors have generated 50 mJ of 16.9-microm radiation by stimulated rotational Raman scattering in 3 atm of H(2) gas pumped by a CO( 2) TEA-laser source and achieved 25% peak power, or 40% peak photon conversion efficiency.
Abstract: We have generated 50 mJ of 16.9-microm radiation by stimulated rotational Raman scattering in 3 atm of H(2) gas pumped by a CO(2) TEA-laser source. Threshold was reached by injection of a few microjoules of 16.9-microm radiation generated by four-wave mixing. We achieved 25% peak power, or 40% peak photon conversion efficiency.