The electron spin of nitrogen--vacancy (NV) centers in diamond offers a solid-state quantum bit and enables high-precision magnetic-field sensing on the nanoscale. Implementation of these approaches ...in a fiber format would offer unique opportunities for a broad range of technologies ranging from quantum information to neuroscience and bioimaging. Here, we demonstrate an ultracompact fiber-optic probe where a diamond microcrystal with a well-defined orientation of spin quantization NV axes is attached to the fiber tip, allowing the electron spins of NV centers to be manipulated, polarized, and read out through a fiber-optic waveguide integrated with a two-wire microwave transmission line. The microwave field transmitted through this line is used to manipulate the orientation of electron spins in NV centers through the electron-spin resonance tuned by an external magnetic field. The electron spin is then optically initialized and read out, with the initializing laser radiation and the photoluminescence spin-readout return from NV centers delivered by the same optical fiber.
We theoretically and experimentally demonstrate that the light shift of the coherent population trapping resonance frequency depends on the buffer gases pressure. The light shift suppression becomes ...impossible when a certain value of the buffer gases pressure is exceeded. We estimate the minimal dimensions of an atomic cell at which the zero light shift and the lowest ground-state relaxation rate can be achieved simultaneously. A new technique of the light shift cancellation by means of a feedback utilizing the RF power modulation is proposed.
The optical spectrum of a vertical-cavity surface-emitting laser under microwave frequency current modulation is asymmetric in most cases, i.e., sidebands equidistant from the carrier have unequal ...powers. Spectra asymmetry is conventionally explained as a result of amplitude modulation affecting a phase-modulated field, but this approach does not give a comprehensive description of the asymmetry. We performed a sequential analysis based on Maxwell's equations accounting for the nonlinear interaction of five spectral components of the laser field. This approach predicted a non-global asymmetry of the spectrum and a new resonant feature in the dependence of the second sidebands' power ratio on the injection current, which we demonstrate experimentally.
Molecular nitrogen is often used as a buffer gas in cells with alkali metals due to its known ability to quench resonant fluorescence. It is widely believed that the suppression of spontaneous ...emission decreases the width of coherent population trapping resonance. However, our recent results have not confirmed this positive action of molecular nitrogen within the typical range of
87
Rb concentrations and buffer gas pressures. On the opposite, we have observed the negative influence of quenching, the decrease in contrast of the coherent population trapping resonance in
–
configuration. In this work, we further confirm these results implementing the Ramsey spectroscopy, and compare the characteristics of the central fringe in nitrogen and neon, and show that the latter provides a significantly better contrast-to-width ratio.
Motivated by recent developments in atomic frequency standards employing the effect of coherent population trapping (CPT), we propose a theoretical framework for describing the CPT resonances. Our ...extended model includes several realistic experimental factors not accounted for in the standard approaches, namely, the FM-based technique for generating the error signal, skewed laser spectrum, etc. We provide a simple yet non-trivial analytical solution revealing the magnitude and structure of the light shift. The performance of the model is checked against numerical simulations, the agreement is good to perfect.
—A method for estimating the stability of emission parameters of external cavity diode lasers to mechanical impacts in the audio frequency range is proposed and tested. Comparison results of lasers ...with a diffraction grating and with an intracavity interference filter are presented. Features in the response of the laser emission frequency to an external acoustic perturbation are shown.
Absorption features in cells with antirelaxation coating in D2 -lines of alkali metal atoms due to the competition of cyclic and open transitions lying within the Doppler contour are studied. In ...cells of this type ensemble of atoms is optically pumped over all velocities and the entire volume of the cell during the characteristic time T, which noticeably exceeds local pumping times related to resonant atomic velocities. If the frequency scanning T, the retardation effect results in significant distortion of the laser wave absorption contour and to emergence of the hysteresis phenomenon. The developed theory for a realistic scheme of atomic levels with one cyclic and two open transitions describes experimentally observed absorption contours, their dependence on the light power and the frequency scanning direction.
A new modification of external optical feedback (OFB) was used to narrow the line of a diode laser (DL). A `whispering gallery' (WG) mode of a high-
Q microsphere was excited by means of frustrated ...total internal reflection while the feedback for optical locking of the laser was provided by the intracavity Rayleigh backscattering. The ∼600 MHz beatnote of the two laser diodes optically locked to a pair of orthogonally polarized modes of the same microresonator had the indicated spectral width of 20 kHz, and the stability of 2×10
−6 over averaging time of 10 s. The feasibility of miniature sub-kHz-line width laser is discussed.
Motivated by recent developments in atomic frequency standards employing the effect of coherent population trapping (CPT), we propose a theoretical framework for the frequency modulation spectroscopy ...of the CPT resonances. Under realistic assumptions we provide simple yet non-trivial analytical formulae for the major spectroscopic signals such as the CPT resonance line and the in-phase/quadrature responses. We discuss the influence of the light shift and, in particular, derive a simple expression for the displacement of the resonance as a function of modulation index. The performance of the model is checked against numerical simulations, the agreement is good to perfect. The obtained results can be used in more general models accounting for light absorption in the thick optical medium.
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