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Results for “RING LASERS”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2012

Enhanced ring lasers: a new measurement tool for Earth sciences

We report the progress in the technology of fabrication of large ring lasers that has resulted in an increase in instrumental rotation sensitivity by as much as a factor of 3, to {delta}{Omega} = 1.2 Multiplication-Sign 10{sup -11} rad s{sup -1} Hz{sup -1/2}, which makes the domain of changes in the angular velocity of Earth's rotation, {Delta}{Omega}/{Omega} Almost-Equal-To 10{sup -9}, accessible to a local rotation sensor. New studies show that the largest contribution to the observed deviation in sensor performance with respect to the computed shot noise limit is caused by the micro-seismic background activity of the Earth. Our efforts have been concentrated on the improvement of sensor stability, including correction of drift effects, which are caused by the aging of the laser gas, fixing scale factor instabilities induced by atmospheric pressure variations, and minimising the temperature variations resulting from corresponding adiabatic expansion and compression of the local air around the instrument. To achieve this, we have recently introduced a pressure-stabilising vessel with dimensions slightly larger than the ring laser apparatus, such that it encloses the entire structure. By monitoring the optical frequency in the ring laser cavity continuously and stabilising the scale factor in a closed loop system with the pressure-stabilising vessel, it has become possible to extend the range of sensor stability from the short term (1 - 3 days) to well into the mid-term regime (>40 days), and possibly even well beyond that. Once a sufficiently long timeseries of the ring laser data has been recorded, we will be able to define the range of temporal stability in more detail. The extension of the regime of stability gives access to geophysical signals at frequencies substantially lower than previously observable with ring lasers. (laser applications and other topics in quantum electronics)

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

A self-injected, diode-pumped, solid-state ring laser for laser cooling of Li atoms

We have constructed a solid-state light source for experiments with laser cooled lithium atoms based on a Nd:Y V O{sub 4} ring laser with second-harmonic generation. Unidirectional lasing, an improved mode selection, and a high output power of the ring laser were achieved by weak coupling to an external cavity which contained the lossy elements required for single frequency operation. Continuous frequency tuning is accomplished by controlling two piezoelectric transducers (PZTs) in the internal and the external cavities simultaneously. The light source has been utilized to trap and cool fermionic lithium atoms into the quantum degenerate regime.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2018

Generation regimes of a solid-state coupled-cavity ring laser

Based on the experimental studies we have shown that when an inhomogeneous magnetic field is applied to an active YAG : Nd crystal, a solid-state coupled-cavity ring laser is characterised by the following generation regimes: stationary unidirectional regime, self-modulation regimes of the first and second kinds, and dynamic chaos regime. Transitions between these generation regimes were carried out when the magnet was moved over the surface of the YAG : Nd single crystal, which made it possible to control the radiation dynamics. (paper)

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2013

Control over the performance characteristics of a passively mode-locked erbium-doped fibre ring laser

We report an all-fibre ultrashort pulse erbium-doped ring laser passively mode-locked by single-wall carbon nanotubes dispersed in carboxymethylcellulose-based polymer films. Owing to intracavity dispersion management and controlled absorption in the polymer films, the laser is capable of generating both femto- and picosecond pulses of various shapes in the spectral range 1.53 – 1.56 μm. We have demonstrated and investigated the generation of almost transform- limited, inversely modified solitons at a high normal cavity dispersion. (control of laser radiation parameters)

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Modulational instability and soliton trains in a model for two-mode fiber ring lasers

A model of orthogonally polarized two-field fiber ring laser with a linear gain is considered, with emphasis on the continuous-wave stability and the existence of soliton trains. The continuous-wave stability analysis is carried out within the framework of the modulational-instability approach, the variations of the gain spectrum with the modulation frequency and characteristic parameters of the model give rise to a rich variety of stability features including single-band and multiband stability regions. Seeking for pulse structures of the model, the two coupled cubic complex Ginzburg–Landau equations describing individual mode propagations are transformed into a set of coupled, first-order nonlinear ordinary-differential equations for the amplitudes and phases of the two modes. Numerical simulations of the last set of coupled equations indicate that in the anomalous dispersion regime, envelopes of the two fields are periodic trains of pulses the amplitudes of which are affected by the linear gain.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2019

Frequency characteristics of a gas coupled-cavity ring laser

Based on a theoretical model describing the lasing dynamics in a gas ring laser (GRL) with coupled cavities, we have investigated the frequency characteristics of radiation. The conditions are found under which an increase in the scale factor is the largest. The regime of frequency locking of counterpropagating waves is studied. It is shown that the lock-in region in a GRL with an antiphase optical coupling of the cavities remains the same as without an additional cavity. The conditions are determined under which multistability of the radiation characteristics arises in a coupled-cavity GRL. In the numerical solution of the equations of the considered theoretical model, three branches of the frequency response are found. (paper)

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2012

Application of ring lasers to determine the directions to the poles of Earth's rotation

Application of a ring laser to determine the directions to the poles of Earth's rotation is considered. The maximum accuracy of determining the directions is calculated, physical and technical mechanisms that limit the accuracy are analysed, and the instrumental errors are estimated by the example of ring He - Ne lasers with Zeeman biasing. (laser applications and other topics in quantum electronics)

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2019

Ring laser gyroscopes in the underground Gran Sasso Laboratories

Gyroscopes IN GEneral Relativity (GINGER) is a proposed experiment with the aim of measuring the gravito-electric (known also as De Sitter effect) and gravito-magnetic effects (or Lense – Thirrings effect) in a ground laboratory, foreseen by general relativity, through an array of large dimension ring laser gyroscopes. The site is located inside the Gran Sasso laboratories (LNGS) of INFN, under more than one thousand meter underground, well protected from surface perturbations. GINGERINO is a square ring-laser prototype with 3.6 m side, which has been built to investigate the level of noise of this site. GINGERINO has already completed its task, showing the advantage of the underground location. It cannot reach the sensitivity suitable for the fundamental physics measurements, but it can provide important data for geophysics and seismology. Its high sensitivity in the frequency band of fraction of Hz and its location in a seismically active area make it suitable for seismology studies. It recorded a sequence of central Italy earthquakes in the autumn of 2016 and many other events both from near field and from far field. The analysis of 90 days of continuous operation shows that its duty cycle is higher than 95 %, with a quantum shot noise limit of the order of 10{sup −10} rad s{sup −1} Hz{sup −1/2}. (paper)

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Frequency of self-modulation oscillations in a solid-state coupled-cavity ring laser

Self-modulation oscillations of the intensity of a solid-state coupled-cavity ring laser are theoretically investigated. The results obtained analytically show that external optical coupling allows the frequency of self-modulation oscillations to be varied in a wide range (from a few kilohertz to hundreds of megahertz). Using coupled cavities, it is possible to significantly weaken the influence of the coupling of counterpropagating waves through backscattering on the self-modulation frequency and to increase the scale factor that determines the dependence of the self-modulation frequency on the rotation velocity. (paper)

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

Generation of ultrashort pulses with minimum duration of 90 fs in a hybrid mode-locked erbium-doped all-fibre ring laser

Regimes of ultrashort pulse generation in an erbium-doped all-fibre ring laser with hybrid mode locking based on single-wall carbon – boron nitride nanotubes and the nonlinear Kerr effect in fibre waveguides are studied. Stable dechirped ultrashort pulses are obtained with a duration of ∼90 fs, a repetition rate of ∼42.2 MHz, and an average output power of ∼16.7 mW, which corresponds to a pulse energy of ∼0.4 nJ and a peak laser power of ∼4.4 kW. (control of laser radiation parameters)

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2019

Spontaneous phase symmetry breaking in a gas coupled-cavity ring laser

A theoretical model is proposed that describes the lasing dynamics in a gas ring laser (GRL) with coupled cavities. The conditions are found under which spontaneous phase symmetry of counterpropagating waves is broken in the GRL with an antiphase optical coupling of the cavities. It is shown that in the case of spontaneous phase symmetry breaking, two branches appear on the GRL frequency characteristic. In some region of frequency nonreciprocity of a ring cavity, both branches can exist under the same conditions. In this case, radiation bistability appears in the GRL, and hysteresis phenomena can be observed. (paper)

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Self-modulation oscillations in a solid-state coupled-cavity ring laser

We propose a theoretical model describing the radiation dynamics in a solid-state coupled-cavity ring laser. Based on the numerical simulation conducted within the framework of this model, we investigate antiphase harmonic oscillations of counterpropagating wave intensities. It is shown that the amplitudes and frequencies of self-modulation oscillations in cases of in-phase and antiphase cavity couplings differ significantly. In the case of antiphase coupling, a new possibility of increasing the scale factor with increasing perimeter of the additional cavity is found. The dependence of the frequency of self-modulation oscillations on the optical nonreciprocity produced in the main cavity by a constant magnetic field is studied experimentally. Comparison of experimental and theoretical results shows good agreement between theory and experiment. (lasers)

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2012

Additive mode locking based on a nonlinear loop mirror ring laser

We present an experimental demonstration of additive pulse mode locking based on a nonlinear loop mirror ring laser. The proposed design uses nonlinear phase shifts induced by a loop mirror. The results show that interference between two overlapping pulses from two coupled fibres, containing a nonlinear medium for power-dependent phase modulation, leads to pulse compression, and can provide mode locking with different repetition rates depending on the interplay or combination between the modulated frequency (active mode locking) and the nonlinearity (passive mode locking) generated in the loop mirror.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2014

Narrow-band erbium-doped fibre linear–ring laser

We have demonstrated a narrow-band linear – ring fibre laser with an output power of 15 mW at a wavelength of 1.55 μm and an emission bandwidth less than 5 kHz. The laser frequency is stabilised by an unpumped active fibre section and fibre Bragg grating. The fibre laser operates in a travelling wave mode, which allows the spatial hole burning effect to be avoided. At a certain pump power level, the laser switches from continuous mode to repetitivepulse operation, corresponding to relaxation oscillations. (control of laser radiation parameters)

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Generation of light and dark soliton trains in a dissipative four-wave mixing, mode-locked fibre ring laser

We consider a model of a dissipative four-wave mixing, mode-locked fibre ring laser with an intracavity interferometer. The necessary conditions required for mode locking are presented. A pulse train generation is numerically simulated at different repetition rates and gain levels. Admissible ranges of values, for which successful mode locking is possible, are found. It is shown that in the case of normal dispersion of the resonator, a laser with an intracavity interferometer can generate a train of pulses with an energy much greater than that in the case of anomalous dispersion. (paper)

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

On the possibility of using metamaterials in a ring laser gyroscope

An approach is proposed that ensures a theoretically unlimited improvement in the sensitivity of ring laser gyroscopes (RLGs) to rotation. Basic to this approach is the filling of the optical path in an RLG (outside its gain element) with two different optical media: a conventional optical medium with a refractive index n > 1 and a so-called metamaterial with n < 0. We consider effects that limit the real sensitivity of the proposed approach. (letters)

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2014

Synchronisation of self-oscillations in a solid-state ring laser with pump modulation in the region of parametric resonance between self-modulation and relaxation oscillations

The synchronisation of the self-modulation oscillation frequency in a Nd : YAG ring laser by an external periodic signal modulating the pump power in the region of parametric resonance between self-modulation and relaxation oscillations is studied theoretically and experimentally. The characteristic features of synchronisation processes in lasers operating in the self-modulation regime of the first kind and in the regime with a doubled self-modulation period are considered. Two bistable branches of synchronisation of self-modulation oscillations are found by numerical calculation. The experimental data agree well with the numerical simulation results for one of these branches, but the other branch of bistable self-modulation oscillations was not observed experimentally. (control of laser radiation parameters)

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2013

Bistability of self-modulation oscillations in an autonomous solid-state ring laser

Bistable self-modulation regimes of generation for a ring YAG : Nd chip laser with the counterpropagating waves asymmetrically coupled via backward scattering are simulated numerically. Two branches of bistable self-modulation regimes of generation are found in the domain of the parametric resonance between the selfmodulation and relaxation oscillations. The self-modulation regimes observed in earlier experiments pertain to only one of the branches. Possible reasons for such a discrepancy are considered, related to the influence of technical and natural noise on the dynamics of solid-state ring lasers. (control of laser radiation parameters)

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗