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Topical Meeting on Optical Bistability (OB)

Gain/Feedback Approach to Optical Instabilities in Sodium Vapor

John F. Valley, G. Khitrova, H. M. Gibbs

Published Jan 1, 1988• 4 citations
Publisher

Abstract

We use the gain-feedback approach1 to explain a number of instabilities observed in sodium vapor with the laser frequency vL tuned to the defocusing side of line center at v0. The gain curve, which includes motion of the atoms, predicts two regions of possible gain: Rayleigh gain for frequencies v just above vL and Raman gain for v ≅vL - vR, where vR is the on-resonance Rabi frequency; see Fig. 1.2 Lasing based on these two gain mechanisms has been seen in three different feedback configurations. The new observations are: Rayleigh-gain lasing with no external mirrors using the distributed feedback of counterpropagating pump beams, Rayleigh-gain lasing without a foreign gas, Raman-gain lasing in a ring cavity (see Fig. 2), and both Rayleigh and Raman lasing using a single feedback mirror.

DOI
10.1364/obi.1988.fc.3

Related papers

GAIN/FEEDBACK APPROACH TO OPTICAL INSTABILITIES IN SODIUM VAPOR

G. Khitrova, John F. Valley, H. M. Gibbs

The gain/feedback approach to lasing and optical instabilities has been applied to sodium vapor driven by a near-resonant intense field. The observed lasing frequencies agree with the two-beam-coupling gain curve calculated for a Doppler-broadened two-level medium. Rayleigh-gain lasing is seen with no external cavity using counterpropagating beams, and Raman gain lasing is seen in a ring cavity.

Le Journal de Physique Colloques•Jun 1, 1988•0 citations

Gain-feedback approach to optical instabilities in sodium vapor

G. Khitrova, John F. Valley, H. M. Gibbs

The gain-feedback approach to lasing and optical instabilities has been applied to sodium vapor driven by a nearly resonant intense field. The observed lasing frequencies agree with the two-beam-coupling gain curve calculated for a Doppler-broadened two-level medium. Rayleigh-gain lasing is seen for no external cavity with use of counterpropagating beams, and Raman-gain lasing is seen in a ring cavity.

Physical Review Letters•Mar 21, 1988•120 citations

Observation of Raman-Gain Lasing and Four-Wave Mixing in Sodium Vapor

John F. Valley, G. Khitrova, H. M. Gibbs

The Doppler-broadened Raman gain of sodium vapor with a strong cw pump lases within a ring cavity. This lasing four-wave mixes with the pump to produce a third, complementary beam. Observations agree with theory only if atomic motion is included.

Conference on Lasers and Electro-Optics•Apr 25, 1988•0 citations

Optical Instabilities in Sodium Vapor and Vertical Cavity Surface Emitting Lasers

Jeffrey W. Grantham

This dissertation investigates three different optical instabilities: cw conical emission, bifurcations of optical transverse solitary waves, and asymmetric gain modification in a vertical cavity surface emitting laser (VCSEL). The first two instabilities occur in sodium vapor while the third occurs in a new type of semiconductor laser. For the conical emission instability, the first comparison and agreement between theory and experiment is given. The conical emission process is modeled as a series of nonlinear effects including self-trapping of the pump beam, Doppler-broadened Raman-gain amplification of Doppler-broadened resonance fluorescence, propagational four-wave mixing, and diffraction and pump-induced refraction of the new frequencies. Each step of the emission process is thoroughly examined and explained. Detailed comparisons are made between experimental observables and numerical calculations including near-field and far-field spatial profiles, frequency spectra, and cone angles. All comparisons show good agreement. In a different but related experiment, bifurcations of optical transverse solitary waves are studied for one-way propagation through a sodium vapor cell. Two types of phase encoding seed transverse bifurcations which result in transverse cell-exit profiles with the beauty rivaling that of a kaleidoscope. The cell-exit profiles are stationary in time, reproduce completely when the power or frequency is scanned, and agree well with one-way computations. Evidence is also presented for the first observation of a double-peaked Raman gain. In the third experiment, a temporal instability is examined in a GaAs VCSEL. Strong evidence is presented for an asymmetric gain modification induced when a strong optical signal is injected into the Fabry-Perot transmission peak of the VCSEL while it is lasing. This gain modification results in increased absorption on the high frequency side of the injected signal and increased gain on the low frequency side as manifested by the formation of an optical sideband. The frequency of the sideband depends on the intensity of the injected signal with frequencies (> 50 GHz) well beyond the predicted relaxation oscillation frequency being observed. Very efficient nondegenerate four-wave mixing is also observed.

•Jan 1, 1991•0 citations

Interpretation for Rayleigh self-oscillations in a pure sodium vapor driven by counterpropagating light beams

Martine Le Berre, Elisabeth Ressayre, Andree A. Tallet

With the intent to explain the onset of a Rayleigh instability in a pure sodium cell driven by counterpropagating light beams, we report a theory that includes pump-depletion effects. A model is developed for fast-moving atoms that predicts the occurrence of a Rayleigh instability for sufficiently large concentration, which may explain the experimental observation.

Physical Review A•Oct 1, 1992•3 citations

Frequency correlated laser beam generation in sodium vapor: sodium-density and pump-intensity dependence

Prem Kumar, Bernard Matthew Poelker

When sodium vapor is irradiated with a single-frequency dye laser (pump) tuned in the vicinity of either of the Doppler-broadened D lines and enclosed in an optical cavity, Raman shifted oscillation builds up, which is blue shifted for a blue-detuned pump and red shifted for a red-detuned pump by 1.772 GHz (sodium ground-state hyperfine splitting).1 The gain mechanism responsible for this Raman-laser action can be understood by modeling sodium as a three-level atom. The Raman laser frequency is highly correlated with that of the pump as demonstrated earlier by observing a beat frequency bandwidth between the two lasers of as low as 17 kHz.2 (The pump had rms frequency fluctuation of the order of 10 MHz.) For spectroscopic applications, for example, frequency correlated laser beams are commonly generated using acoustooptic techniques which are difficult to implement beyond the gigahertz region. The Raman laser technique is extendable, in principle, even to the millimeter range. Here we present measurements of the sodium-density and pump-intensity dependence of the Raman-laser output and compare the results with those predicted by the three-level-atom model.

Annual Meeting Optical Society of America•Jan 1, 1988•0 citations
We use the gain-feedback approach1 to explain a number of instabilities observed in sodium vapor with the laser frequency vL tuned to the defocusing side of line center at v0. The gain curve, which includes motion of the atoms, predicts two regions of possible gain: Rayleigh gain for frequencies v just above vL and Raman gain for v ≅vL - vR, where vR is the on-resonance Rabi frequency; see Fig. 1.2 Lasing based on these two gain mechanisms has been seen in three different feedback configurations. The new observations are: Rayleigh-gain lasing with no external mirrors using the distributed feedback of counterpropagating pump beams, Rayleigh-gain lasing without a foreign gas, Raman-gain lasing in a ring cavity (see Fig. 2), and both Rayleigh and Raman lasing using a single feedback mirror.
This dissertation investigates three different optical instabilities: cw conical emission, bifurcations of optical transverse solitary waves, and asymmetric gain modification in a vertical cavity surface emitting laser (VCSEL). The first two instabilities occur in sodium vapor while the third occurs in a new type of semiconductor laser. For the conical emission instability, the first comparison and agreement between theory and experiment is given. The conical emission process is modeled as a series of nonlinear effects including self-trapping of the pump beam, Doppler-broadened Raman-gain amplification of Doppler-broadened resonance fluorescence, propagational four-wave mixing, and diffraction and pump-induced refraction of the new frequencies. Each step of the emission process is thoroughly examined and explained. Detailed comparisons are made between experimental observables and numerical calculations including near-field and far-field spatial profiles, frequency spectra, and cone angles. All comparisons show good agreement. In a different but related experiment, bifurcations of optical transverse solitary waves are studied for one-way propagation through a sodium vapor cell. Two types of phase encoding seed transverse bifurcations which result in transverse cell-exit profiles with the beauty rivaling that of a kaleidoscope. The cell-exit profiles are stationary in time, reproduce completely when the power or frequency is scanned, and agree well with one-way computations. Evidence is also presented for the first observation of a double-peaked Raman gain. In the third experiment, a temporal instability is examined in a GaAs VCSEL. Strong evidence is presented for an asymmetric gain modification induced when a strong optical signal is injected into the Fabry-Perot transmission peak of the VCSEL while it is lasing. This gain modification results in increased absorption on the high frequency side of the injected signal and increased gain on the low frequency side as manifested by the formation of an optical sideband. The frequency of the sideband depends on the intensity of the injected signal with frequencies (> 50 GHz) well beyond the predicted relaxation oscillation frequency being observed. Very efficient nondegenerate four-wave mixing is also observed.
When sodium vapor is irradiated with a single-frequency dye laser (pump) tuned in the vicinity of either of the Doppler-broadened D lines and enclosed in an optical cavity, Raman shifted oscillation builds up, which is blue shifted for a blue-detuned pump and red shifted for a red-detuned pump by 1.772 GHz (sodium ground-state hyperfine splitting).1 The gain mechanism responsible for this Raman-laser action can be understood by modeling sodium as a three-level atom. The Raman laser frequency is highly correlated with that of the pump as demonstrated earlier by observing a beat frequency bandwidth between the two lasers of as low as 17 kHz.2 (The pump had rms frequency fluctuation of the order of 10 MHz.) For spectroscopic applications, for example, frequency correlated laser beams are commonly generated using acoustooptic techniques which are difficult to implement beyond the gigahertz region. The Raman laser technique is extendable, in principle, even to the millimeter range. Here we present measurements of the sodium-density and pump-intensity dependence of the Raman-laser output and compare the results with those predicted by the three-level-atom model.