Search

Optical frequency combs generated by parametric modulation of optical microresonators are usually described by lumped-parameter models, which do not account for the spatial distribution of the modulation. This study highlights the importance of this spatial distribution in the Surface Nanoscale Axial Photonics (SNAP) platform, specifically for elongated SNAP bottle microresonators with a shallow nanometre-scale effective radius variation along its axial length. SNAP bottle microresonators have much smaller free spectral range and may have no dispersion compared to microresonators with other shapes (e.g., spherical and toroidal), making them ideal for generating optical frequency combs with lower repetition rates. By modulating parabolic SNAP bottle microresonators resonantly and adiabatically, we show that the flatness and bandwidth of the optical frequency comb spectra can be enhanced by optimizing the spatial distribution of the parametric modulation. The optimal spatial distribution can be achieved experimentally using piezoelectric, radiation pressure, and electro-optical excitation of a SNAP bottle microresonator. "Previous studies investigating the creation of optical frequency combs through parametric modulation of microresonators rely on lumped-element models that do not consider how the modulations are spatially distributed. The current study underscores the crucial role of these spatial distributions in SNAP bottle microresonators, particularly in producing optical frequency combs with low repetition rate. [ABSTRACT FROM AUTHOR]

Time crystals represent temporal analogues of the spatial self-ordering exhibited by atomic or molecular building blocks of solid-state crystals. The pursuit of discrete time crystals (DTCs) in periodically forced Floquet closed systems has revealed how they can evade thermalization and loss of temporal order. Recently, it has been shown that even with coupling to the ambient and its concomitant noise, some states maintain their time crystalline order, forming dissipative DTCs. Here, we introduce a scheme for the realization and state control of dissipative DTCs hinging on pumping a Kerr optical resonator with a phase-modulated continuous-wave laser. We show the possible symmetry breaking states possess temporal long-range order and analyze the phase noise of the accompanying signature radio frequency (RF) subharmonic. Besides offering a technique for generating high-spectral-purity RF signals, this versatile platform empowers controlled switching between various DTC states through accessible experimental knobs, hence facilitating the future study of DTC phase transitions. Discrete time crystals are a new state of matter emerging via spontaneous discrete translational symmetry breaking in time. The authors demonstrate that a dissipative discrete time crystal appears in an optical microcavity pumped by a phase-modulated continuous wave laser, offering a new route to study this exotic crystal phase. [ABSTRACT FROM AUTHOR]

Optical cavities, with both optimized resonant conditions and high quality factors, are important metrological tools. In particular, they are used for laser gravitational wave (GW) detectors. In order to have high cavity powers in GW detectors, it is necessary to suppress the parametric instability and to reduce the loss in the arm caused by point absorbers by damping the resonant conditions of harmful higher order optical modes (HOOM). This can be achieved effectively by using non spherical mirrors in symmetric Fabry–Perot (FP) cavities by increasing roundtrip losses of HOOMs Ferdous F et al 2014 Phys. Rev. A 90 033826; Matsko A et al 2016 Phys. Rev. D 93 083010. FP cavities in most of the GW detectors have non-identical mirrors to optimize clipping losses and reduce thermal noise by reducing the beam size on one side of the cavity facing to the beam splitter and recycling cavities. We present here a general method to design non spherical non-identical mirrors in non-symmetric FP cavities to damp HOOMs. The proposed design allows us to suppress the loss of the arm power caused by point absorbers on test masses. [ABSTRACT FROM AUTHOR]

We analyze theoretically both the fundamental and the technical quantum limitations of the sensitivity of a passive resonant optical gyroscope based on a high finesse monolithic optical microcavity. We show that the quantum back action associated with the resonantly enhanced optical cross- and self-phase modulation results in the standard quantum limit of the angle random walk of the gyroscope, which reaches approximately 0.2 deg/hr 1/2 for a millimeter scale CaF 2 whispering gallery mode resonator based device. [ABSTRACT FROM AUTHOR]

• Quantum measurements. • Back action and Standard Quantum Limit. • Back action evading. • Variational measurement: narrow band back action evading. • Dichromatic variational measurement: broad band back action evading. Quantum back action imposes fundamental sensitivity limits to the majority of quantum measurements. The effect results from the unavoidable contamination of the measured parameter with the quantum noise of a meter. Back action evading measurements take advantage of the quantum correlations introduced by the system under study to the meter and allow overcoming the fundamental limitations. The measurements are frequently restricted in their bandwidth due to a finite response time of the system components. Here we show that probing a mechanical oscillator with a dichromatic field with frequencies separated by the oscillator frequency enables independent detection in two outputs and complete subtraction of the measurement noise associated with the quantum back action. [ABSTRACT FROM AUTHOR]

We report on the study of widely tunable, resonant single-sideband electro-optical modulators based on whispering gallery mode (WGM) resonators, made out of electro-optically active materials. The modulation process involves interaction of different WGM families with an externally applied microwave field. The tunability results from the unequal response of the mode families to either a temperature change or to an applied voltage. We show that the modulator can be used as an efficient microwave photonic receiver that operates either in direct or coherent regime. Due to its resonant nature, the high-Q electro-optical modulator also can be used as a resolution booster for a low-resolution RF spectrum analyzer. [ABSTRACT FROM PUBLISHER]

Abstract: We report on a study of optical properties of whispering gallery mode resonators made out of as-grown nominally pure lithium niobate crystals. We have observed a surprising dynamic modification of the spectrum of the resonators illuminated with the near infrared light. We attribute this effect to the photorefractive damage of the resonator host material. [Copyright &y& Elsevier]

We discuss practical aspects of building atomic clocks consisting of an optoelectronic oscillator stabilized with the electromagnetically induced transparency resonance in a 87Rb atomic vapour cell, where a vertical cavity surface emitting laser (VCSEL) is used as a light source. In particular, we show how the variable microwave power injection into the VCSEL, its optical injection-locking, and the phase stability of the optical-microwave link influences the stability of the clocks. [ABSTRACT FROM AUTHOR]

Abstract: We report on the fabrication technique of ultra high Q optical crystalline whispering gallery mode microresonators and discuss their properties. The technique is suitable for the majority of available optical crystals and for production of resonators with small size. To validate the method, we made CaF2 resonators with Q factors exceeding 4×108 and a diameter smaller than 100μm. A single mode resonator has also been fabricated. Possible utilization of these new resonators in quantum optics is discussed. [Copyright &y& Elsevier]

Abstract: We describe theoretically a simple technique for analyzing the conversion efficiency and the oscillation threshold of all-resonant intracavity Raman lasers. The method is based on a dependence of the ring-down time of the pump cavity mode on the energy accumulated in the cavity. [Copyright &y& Elsevier]

Theoretical analysis shows that the correlation time of a photon pair is closely related to the spectrum of two-photon light. This entails limitations on the shortest achievable two-photon correlation time. These limitations are important for quantum optical metrology and information processing applications, especially those involving quasi-monochromatic light. In this paper we present a more rigorous proof of the fact that the shortest possible two-photon correlation time is limited by approximately the inverse width of the optical spectrum. We further show that this limit can be closely approached with Type-I spontaneous parametric down-conversion at a specific pump wavelength. This study also results in the prediction of very unusual parametric down-conversion spectra, suggesting a method for engineering of frequency-entangled two-photon states. [ABSTRACT FROM AUTHOR]

Abstract: We present a scheme for an all-optical self-oscillating magnetometer based on the opto-electronic oscillator stabilized with an atomic vapor cell. We demonstrate a proof of the principle with DC magnetic field measurements characterized by 2×10−7 G sensitivity and 1–1000 mG dynamic range. [Copyright &y& Elsevier]

We studied experimentally the influence of thermal atomic motion on light propagation in a vacuum atomic vapour cell above room temperature. We found that atomic motion introduces sizable changes in the spectral properties of the medium, such as dispersion and absorption, if the conditions for coherent population trapping are fulfilled. In particular, studying the group delay of light in the atomic vapour, we confirm the theoretical predictions of Kocharovskaya et at, (2001, Phys, Rev, Lett,. 86, 628) and demonstrate that a coherent atomic medium has light dragging abilities large enough to make feasible the realization of frozen light based on atomic motion. We also demonstrate that dragging can be observed in measurements of the electromagnetically induced transparency resonance width, as well as in group delay measurements. [ABSTRACT FROM AUTHOR]

• A trapped diamagnetic particle in an inhomogeneous magnetic field is studied analytically. • Compact expressions for the frequency and eddy-current-related Q-factor are derived. • The Q-factor grows with reduction of the particle size and the magnetic susceptibility. • Usefulness of the pendulum for the gravity constant measurements is highlighted. We discuss eddy-current-induced limitations of the attenuation of mechanical motion of a diamagnetic particle trapped by an inhomogeneous magnetic field in the Earth's gravitational potential. We show that the mechanical frequency of the particle oscillation is independent on the particle properties and is proportional to the free fall acceleration constant, similarly to the classical mechanical pendulum. The frequency can be used to measure the gravity field. The eddy-current induced attenuation constant does not depend on the mass of the particle and reduces with the particle volume. The quality factor of the mechanical motion can be as high as 109 and is comparable with the attenuation due to interaction of the particle with incompletely evacuated air. A possibility of usage of the particle as a quantum mechanical system is discussed. [ABSTRACT FROM AUTHOR]

We report on the study of near-infrared photorefractivity in highly Mg doped as-grown congruent LiNbO3 forming a whispering gallery mode resonator. The resonator is pumped with 780 nm light. We have observed a change of the ordinary index of refraction of the material exceeding 8×10-5. We show that the basic features of the photorefraction in this type of crystal is different from the photorefraction in nominally pure as-grown congruent LiNbO3 and explain the origin of this difference. [ABSTRACT FROM AUTHOR]

We study theoretically and demonstrate experimentally generation of coherent optical frequency combs in a sapphire whispering gallery mode resonator. We verify phase locking of the comb harmonics by demodulating the comb on a fast photodiode and by observing the production of a spectrally pure radio frequency signal. Because of excellent optical and superior mechanical properties of the material, the sapphire resonator is an excellent candidate for the on-chip device integration of the comb oscillator. [ABSTRACT FROM AUTHOR]

Compact, high power lasers with narrow linewidth are important tools for the manipulation of quantum systems. We demonstrate a compact, self-injection locked, Fabry-Perot semiconductor laser diode with high output power at 493 nm. A high quality factor magnesium fluoride whispering gallery mode resonator enables both high passive stability and 1 kHz instantaneous linewidth. We use this laser for laser-cooling, in-situ isotope purifcation, and probing barium atomic ions confined in a radio-frequency ion trap. The results here demonstrate the suitability of these lasers in trapped ion quantum information processing and for probing weak coherent optical transitions. [ABSTRACT FROM AUTHOR]

In this paper, we study an experimental method of evaluation of efficiency of an evanescent field coupling of light to a dielectric whispering gallery mode resonator. We show that change of the relative contrast of the observable optical resonance provides an accurate and complete information about the loaded as well as unloaded bandwidth of the resonator mode. We introduce a model of the coupling that allows for an interpolation of the resonator quality factor using experimental data taken without usage of a frequency tunable narrow line laser, a fast photodiode, as well as a frequency reference. The method is also immune to imperfect geometrical mode matching frequently occurring in a realistic system. We validate this model experimentally at both 1.5 and 4.5μm. [ABSTRACT FROM AUTHOR]