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Showing papers in "Optics Letters in 1984"


Journal ArticleDOI
TL;DR: It is shown that pairs of prisms can have negative group-velocity dispersion in the absence of any negative material dispersion.
Abstract: We show that pairs of prisms can have negative group-velocity dispersion in the absence of any negative material dispersion. A prism arrangement is described that limits losses to Brewster-surface reflections, avoids transverse displacement of the temporally dispersed rays, permits continuous adjustment of the dispersion through zero, and yields a transmitted beam collinear with the incident beam.

987 citations


Journal ArticleDOI
L. F. Mollenauer1, Roger H. Stolen1
TL;DR: The soliton laser as discussed by the authors is a mode-locked laser using pulse compression and solitons in a single-mode fiber to force the laser itself to produce pulses of a well-defined shape and width.
Abstract: The soliton laser, a novel concept in ultrashort-pulse lasers, is a mode-locked laser using pulse compression and solitons in a single-mode fiber to force the laser itself to produce pulses of a well-defined shape and width. Thus the fiber is in one way or another involved in the laser’s feedback loop. Although the basic concept is a general one, we report here primarily on the first successful version[1], based on a sync-pumped, mode-locked color-center laser operating in the 1.5 pm region. To date this color-center soliton laser has directly produced pulses as short as 130 fsec, and has allowed for the production of pulses of as little as 50 fsec FWHM, by compression in a second, external fiber. Other advantages include wide tunability (limited only by power requirements for soliton production in the fiber), output pulses that are always transform limited, easy adjustment for production of ~sech2 pulse shape. and a relative simplicity of construction.

464 citations


Journal ArticleDOI
TL;DR: It is shown that the broadening in the far-field beam divergence, as well as the broadens of each of the longitudinal modes that were observed in phase-locked arrays, may arise from the excitation of an increasing number of supermodes at increasing pumping levels.
Abstract: The optical characteristics of phase-locked semiconductor laser arrays are formulated in terms of the array supermodes, which are the eigenmodes of the composite-array waveguide, by using coupled-mode theory. These supermodes are employed to calculate the near fields, the far fields, and the difference in the longitudinal-mode oscillation wavelengths of the array. It is shown that the broadening in the far-field beam divergence, as well as the broadening of each of the longitudinal modes that were observed in phase-locked arrays, may arise from the excitation of an increasing number of supermodes at increasing pumping levels.

404 citations


Journal ArticleDOI
TL;DR: Inelastic emission characteristics from individual ethanol droplets (60-microm diameter) containing Rhodamine 6G dye and pumped by a cw laser and confirmed by noting the spectral, temporal, and output-versus-input intensity behavior.
Abstract: Inelastic emission characteristics from individual ethanol droplets (60-microm diameter) containing Rhodamine 6G dye and pumped by a cw laser (514.5 nm) were investigated. Laser emission was confirmed by noting the spectral, temporal, and output-versus-input intensity behavior. The liquid-air boundary of the droplets provides the optical feedback at selected wavelengths corresponding to the morphology-dependent resonances of a spherical droplet.

386 citations


Journal ArticleDOI
Akira Hasegawa1
TL;DR: The modulational instability of a cw optical signal in a glass fiber combined with an externally applied amplitude modulation can be utilized to produce a train of optical solitons with a wide range of pulse width and repetition period.
Abstract: The modulational instability of a cw optical signal in a glass fiber combined with an externally applied amplitude modulation can be utilized to produce a train of optical solitons with a wide range of pulse width (50–1 psec) and repetition period (≲250 psec).

380 citations


Journal ArticleDOI
TL;DR: Spectral superbroadening of ultrashort-pulse propagation in a nonlinear medium is calculated by solving the nonlinear-wave equation more exactly and yields an asymmetric Stokes-anti-Stokes broadening in fair agreement with the experimental observation.
Abstract: Spectral superbroadening of ultrashort-pulse propagation in a nonlinear medium is calculated by solving the nonlinear-wave equation more exactly. The effects of four-wave mixing and pulse deformation on phase modulation are included. The results yield an asymmetric Stokes-anti-Stokes broadening in fair agreement with the experimental observation.

243 citations


Journal ArticleDOI
TL;DR: Pulses of 90-fsec duration from a cavity-dumped colliding-pulse mode-locked laser have been amplified to microjoule energies at 5-kHz repetition rate using a copper-vapor-laser pump source.
Abstract: Pulses of 90-fsec duration from a cavity-dumped colliding-pulse mode-locked laser have been amplified to microjoule energies at 5-kHz repetition rate using a copper-vapor-laser pump source. Near-diffraction-limited focusing and efficient femtosecond continuum generation are demonstrated.

225 citations


Journal ArticleDOI
TL;DR: By using a GaAs/GaAIAs multiple-quantum-well sample as a saturable absorber in an external resonator, it is shown that pulses as short as 1.6 psec are observed, the shortest pulses ever observed to the authors' knowledge from a mode-locked diode laser in a regulator pulse train.
Abstract: By using a GaAs/GaAIAs multiple-quantum-well sample as a saturable absorber in an external resonator, we have passively mode locked a GaAs laser to obtain pulses as short as 1.6 psec, the shortest pulses ever observed to our knowledge from a mode-locked diode laser in a regulator pulse train.

182 citations


Journal ArticleDOI
Marvin B. Klein1
TL;DR: It is observed that beam coupling and degenerate four-wave mixing in high-resistivity, undoped GaAs at 1.06 microm that is due to the photorefractive effect.
Abstract: We have observed beam coupling and degenerate four-wave mixing in high-resistivity, undoped GaAs at 1.06 microm that is due to the photorefractive effect. The photorefractive species is thought to be the deep donor EL2. The measured values of two-wave gain are comparable with those measured in Bi(12)SiO(20). The response time is measured to be 20 microsec at an intensity of 4 W/cm(2). This exceptionally fast photorefractive response time (compared with that of oxide electro-optic materials) is due primarily to the large mobility of GaAs.

172 citations


Journal ArticleDOI
TL;DR: It is shown that two-port homodyning is insensitive to local-oscillator quadrature-phase noise and hence provides a means of detecting reduced quadratures-phase fluctuations (squeezing) and an output signal-to-noise ratio that can be a modest to significant improvement over that of one-port Homodyning and direct detection.
Abstract: A simple but rigorous analysis of the important sources of noise in homodyne detection is presented. Output noise and signal-to-noise ratios are compared for direct detection, conventional (one-port) homodyning, and two-port homodyning, in which one monitors both output ports of a 50-50 beam splitter. It is shown that two-port homodyning is insensitive to local-oscillator quadrature-phase noise and hence provides (1) a means of detecting reduced quadrature-phase fluctuations (squeezing) that is perhaps more practical than one-port homodyning and (2) an output signal-to-noise ratio that can be a modest to significant improvement over that of one-port homodyning and direct detection.

164 citations


Journal ArticleDOI
TL;DR: This work derived theoretically the ultimate sensitivity limits of the grating devices employed either as switches or as gas sensors, and demonstrated new switching and gas-sensing effects in integrated optics using input and output grating couplers and Bragg reflector gratings with 1200 lines/mm on planar SiO-TiO(2) waveguides.
Abstract: We have demonstrated new switching and gas-sensing effects in integrated optics using input and output grating couplers and Bragg reflector gratings with 1200 lines/mm on planar SiO2–TiO2 waveguides. Switching is actuated by adsorption or desorption of water or other adsorbates on the waveguide surface through a change in the effective index of the guided modes under the grating. We derived theoretically the ultimate sensitivity limits of the grating devices employed either as switches or as gas sensors. Switching requires the adsorption and desorption, respectively, of less than one H2O monolayer. Sensors can detect variations in surface coverage of 1/100 of an H2O monolayer.

Journal ArticleDOI
TL;DR: Closed-form analytical solutions are obtained for a passively mode-locked laser for the case in which self-phase modulation and group-velocity dispersion, in addition to the more conventional mechanisms of saturable absorption and gain, shape the laser pulses.
Abstract: Closed-form analytical solutions are obtained for a passively mode-locked laser for the case in which self-phase modulation and group-velocity dispersion, in addition to the more conventional mechanisms of saturable absorption and gain, shape the laser pulses. Provided that the self-phase modulation and group-velocity dispersion are related in a manner similar to that which causes soliton formation in optical fibers, this additional pulse shaping can reduce the pulse duration below the limit otherwise set by the laser bandwidth.

Journal ArticleDOI
TL;DR: A modal coupler, mounted on a single strand of fiber to construct a Mach-Zehnder interferometer with better than a 30-dB on/off ratio, is described.
Abstract: When a single-mode fiber is used at a wavelength below the cutoff wavelength, the fiber guides second-order modes, which travel at different phase velocities from the fundamental mode. Periodically stressing this two-mode fiber once per beat length can cause coherent coupling between the modes. Such a modal coupler has been developed and is described here. Coupling to one of the second-order modes has been achieved, leaving less than -40-dB residual power in the fundamental mode. Two couplers have been mounted on a single strand of fiber to construct a Mach-Zehnder interferometer with better than a 30-dB on/off ratio. The coupler is polarization sensitive and can be used as an in-line polarizer. A 36-dB extinction ratio between polarizations has been observed.

Journal ArticleDOI
TL;DR: An intensity-dependent hysteresis in the transmission of guided waves through a thin-film waveguide with a cladding characterized by an intensity- dependent refractive index is observed.
Abstract: We have observed an intensity-dependent hysteresis in the transmission of guided waves through a thin-film waveguide with a cladding characterized by an intensity-dependent refractive index. Good agreement with theory was obtained.

Journal ArticleDOI
TL;DR: It is shown theoretically that optical bistability will exist in a material whose optical absorption is more than linearly proportional to the degree to which the material is excited.
Abstract: It is shown theoretically that optical bistability will exist in a material whose optical absorption is more than linearly proportional to the degree to which the material is excited. No cavity or external feedback is required. The underlying principle of this bistability appears to be a generalization of several previous independent discussions of mirrorless bistabilities in specific physical systems. This bistability and associated differential gain are demonstrated experimentally using a thermal nonlinearity in a GaAs/GaAlAs multiple-quantum-well semiconductor. Theory and experiment show good agreement.

Journal ArticleDOI
TL;DR: The present result shows the feasibility of operating an internally doubled oscillator for efficiently converting the fundamental to its harmonic in a high-power device.
Abstract: We have demonstrated high-average-power second-harmonic generation with an output power of 5.6 W at 532 nm by intracavity frequency doubling using Type II KTiOPO4 in a Nd:YAG laser oscillator acousto-optically Q switched at 5 kHz.1 The average power achieved, limited only by the power-supply current available in these experiments, was about three times higher than what has been obtained in a state-of-the-art device using LiIO3 as the doubler. More significantly, since no intrinsic limitations, such as saturation and material damage, have yet been observed, further improvement in the power output should be achievable. It is pointed out that previous studies on intracavity second-harmonic generation have been limited to the small-signal case; the present result shows the feasibility of operating an internally doubled oscillator for efficiently converting the fundamental to its harmonic in a high-power device.

Journal ArticleDOI
TL;DR: A new real-time interferometer based on diffraction phenomena is discussed, which consists of a point-diffraction interferometers fabricated on a transmission grating and achieved by simultaneously introducing a phase shift on the three separate channels of diffracted interferograms.
Abstract: A new real-time interferometer based on diffraction phenomena is discussed. It consists of a point-diffraction interferometer fabricated on a transmission grating. The real-time data-analysis capability is achieved by simultaneously introducing a phase shift (piston) on the three separate channels of diffracted interferograms. Mathematical analysis and preliminary observational results are included.

Journal ArticleDOI
Richard E. Teets1
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.

Journal ArticleDOI
TL;DR: It is pointed out the importance of the modulational instability as a possible limiting factor for coherent optical-fiber transmission and the need to address this problem in the near future.
Abstract: We point out the importance of the modulational instability as a possible limiting factor for coherent optical-fiber transmission.

Journal ArticleDOI
TL;DR: An open-loop, all-fiber-optic gyroscope with wide dynamic range and linear scale factor is described, which converts the Sagnac phase shift into a phase shift in a low-frequency electronic signal by using optical phase modulation followed by amplitude modulation to verify the theoretical predictions.
Abstract: An open-loop, all-fiber-optic gyroscope with wide dynamic range and linear scale factor is described. This novel approach converts the Sagnac phase shift into a phase shift in a low-frequency electronic signal by using optical phase modulation followed by amplitude modulation of the electronic signal. Preliminary experimental results verify the theoretical predictions.

Journal ArticleDOI
TL;DR: The wave-front curvature of an incident laser beam can modify the spatial phase modulation of thebeam, and hence the diffraction of the beam, traversing a liquid-crystal film, and it is shown both theoretically and experimentally that this explains the anomalous fine structure in thediffraction ring pattern observed with laser intensities above the Freederickscz transition threshold.
Abstract: The wave-front curvature of an incident laser beam can modify the spatial phase modulation of the beam, and hence the diffraction of the beam, traversing a liquid-crystal film. It is shown both theoretically and experimentally that this explains the anomalous fine structure in the diffraction ring pattern observed with laser intensities above the Freederickscz transition threshold.

Journal ArticleDOI
TL;DR: This work has compressed the 80-psec pulses from a cw mode-locked Nd:YAG laser by a factor of 45 and uses single-mode optical fiber and a compact grating-pair dispersive delay line.
Abstract: We have compressed the 80-psec pulses from a cw mode-locked Nd:YAG laser by a factor of 45. The pulse compressor uses single-mode optical fiber and a compact grating-pair dispersive delay line.

Journal ArticleDOI
James P. Gordon1, R. L. Fork1
TL;DR: Analysis of an optical ring resonator consisting of a prism and two mirrors demonstrates that such a resonator can have adjustable dispersion of either sign.
Abstract: Analysis of an optical ring resonator consisting of a prism and two mirrors demonstrates that such a resonator can have adjustable dispersion of either sign. The dispersion is proportional to the second derivative of the optical path length in the resonator with respect to wavelength. Adjustable dispersion may have important application to the production of ultrashort laser pulses.

Journal ArticleDOI
TL;DR: Single-sideband frequency shifting has been accomplished using traveling acoustic waves to couple the orthogonal polarizations of birefringent fiber using surface and bulk acoustic waves.
Abstract: Single-sideband frequency shifting has been accomplished using traveling acoustic waves to couple the orthogonal polarizations of birefringent fiber. The light coupled from one polarization to the other is shifted in frequency by the frequency of the acoustic wave. An upper sideband is produced in one polarization, a lower sideband in the other. Both surface and bulk acoustic waves have been used. Sideband suppression of better than 30 dB and carriersuppression of better than 20 dB below the desired sideband have been achieved.

Journal ArticleDOI
TL;DR: An in-line polarization rotator has been built into a single-mode birefringent fiber that utilizes periodic twists of the fiber's principal axes, which were formed by rocking the preform as the fiber was drawn.
Abstract: An in-line polarization rotator has been built into a single-mode birefringent fiber. The rotator utilizes periodic twists of the fiber’s principal axes, which were formed by rocking the preform as the fiber was drawn. The polarization conversion between the principal axes is wavelength dependent, with a bandwidth inversely proportional to the number of twist periods. The bandwidth of the present rotator was 4.8 nm for 100% conversion in a fiber length of 170 cm.

Journal ArticleDOI
TL;DR: A new optical technique, based on morphology-dependent peaks in the fluorescence spectra, is-used to determine the evaporation and condensation rates of a linear stream of ethanol droplets.
Abstract: A new optical technique, based on morphology-dependent peaks in the fluorescence spectra, is used to determine the evaporation and condensation rates of a linear stream of ethanol droplets. The droplets are monodispersed, in close proximity to one another, and impregnated with fluorescent dye molecules. On irradiation of the droplets with a single N2 laser pulse, the evaporation or condensation rates can be deduced from the wavelength shift (to the blue or to the red, respectively) of the spectrally narrow (<0.1-nm) structure-resonance peaks in the fluorescence spectra.

Journal ArticleDOI
TL;DR: A continuous-wave dye laser having a self-pumped phase conjugator in place of its usual output mirror will slowly change its own output wavelength with time, caused by a spontaneously moving photorefractive-index grating in the BaTiO(3) crystal.
Abstract: A continuous-wave dye laser having a self-pumped phase conjugator in place of its usual output mirror will slowly change its own output wavelength with time. The laser has a bandwidth of 1.5 GHz and can self-scan to either longer or shorter wavelengths over a 37-nm range. The phase conjugator uses self-pumped four-wave mixing in a BaTiO3 crystal. A ring laser that uses two-wave mixing in the same crystal is also observed to have a frequency offset of a few hertz compared with the frequency of the pumping beam. These two effects are related; both are caused by a spontaneously moving photorefractive-index grating in the BaTiO3 crystal.

Journal ArticleDOI
TL;DR: It is shown that efficient phase conjugation by degenerate four-wave mixing should be possible in semiconductor-doped glasses near the absorption edge.
Abstract: We present a phenomenological theory of the intensity-dependent dielectric function of semiconductor-doped glasses near the absorption edge. It is shown that efficient phase conjugation by degenerate four-wave mixing should be possible in these materials.

PatentDOI
TL;DR: In this paper, a micro-channel spatial light modulator with a photocathode to receive incident light and to provide a spatial distribution of photoelectrons (herein called an electron image) whose spatial number density is proportional to the spatial intensity of the incident light is presented.
Abstract: A microchannel spatial light modulator that has a photocathode to receive incident light and to provide a spatial distribution of photoelectrons (herein called an electron image) whose spatial number density is proportional to the spatial intensity of the incident light. A microchannel plate is provided to receive the photoelectrons and to amplify the electron image. An electro-optic plate is provided to receive the amplified electron image; there is a dielectric mirror coating and an insulating light-blocking layer at one major surface thereof to receive the electron image and a transparent electrode at the other major surface thereof for biasing purposes. All of the foregoing elements are contained within a vacuum housing; suitable electrical potentials are applied to effect the necessary results. The modulator is capable of real-time phase or intensity modulation.

Journal ArticleDOI
TL;DR: Feedback from a self-pumped BaTiO(3) phase-conjugate reflector into an untuned cw dye laser produces substantial line narrowing and generates a recurrent wavelength sweep from the rhodamine 6G peak at 618 nm to as far as 644 nm.
Abstract: Feedback from a self-pumped BaTiO3 phase-conjugate reflector into an untuned cw dye laser produces substantial line narrowing (4–6 GHz) and generates a recurrent wavelength sweep from the rhodamine 6G peak at 618 nm to as far as 644 nm.