Active mode mismatch sensing and control can facilitate optimal coupling in optical cavity experiments such as interferometric gravitational wave detectors. In this paper, we demonstrate a radio-frequency (RF) beam wavefront curvature modulation-based mode mismatch sensing scheme inspired by the previously proposed RF beam jitter alignment sensing scheme. The proposed mode mismatch sensing scheme uses an electro-optic lens (EOL) device that is designed to provide the required beam wavefront curvature actuation, as well as a mode converting telescope that rephases the RF second-order modes and generates a non-vanishing mode mismatch sensing signal. We carefully investigate the total second-order mode generation from the wavefront actuation both analytically and numerically, taking the effects of Gaussian beam size evolution and the second-order mode phase mismatch cancellation into consideration. We demonstrate the second-order mode generation as a function of the incident beam waist size and the electro-optic crystal size, which along with a ``trade-off'' consideration of the beam size at the edges of the crystal and the clipping loss, provides us with guidance for designing the beam profile that interacts with the crystal to improve the EOL modulation efficiency.
Jacob M. Freedman, Matthew J. Storey, Daniel Dominguez
et al.
Here we present an efficient, visible-light, gigahertz-frequency acousto-optic modulator fabricated on a 200 mm wafer in a volume CMOS foundry. Our device combines a piezoelectric transducer and a photonic waveguide within a single microstructure that confines both a propagating optical mode and an electrically excitable breathing-mode mechanical resonance. By tuning the device's geometry to optimize the optomechanical interaction, we achieve modulation depths exceeding 2 rad with 15 mW applied microwave power at 2.31 GHz in a 2 mm long device. This corresponds to a modulation figure of merit of $V_π\cdot L$ = 0.26 Vcm in a visible-light, integrated acousto-optics platform that can be straightforwardly extended to a wide range of optical wavelengths and modulation frequencies. For the important class of gigahertz-frequency modulators that can handle hundreds of milliwatts of visible-light optical power, which are critical for scalable quantum control systems, this represents a 15x decrease in $V_π$ and a 100x decrease in required microwave power compared to the commercial state-of-the-art and existing work in the literature.
John M. Bass, Jeffrey Y. Chen, Gregory M. Nero
et al.
Wavefront correction and beam tracking are critical in applications such as long-range imaging through turbulence and free-space optical communication. For instance, adaptive optics systems are employed to correct wavefront distortions caused by atmospheric turbulence and optical misalignments, while beam tracking systems maintain alignment between separate devices in free-space communication scenarios. Current state-of-the-art approaches offer several high-performance solutions, each tailored to specific correction tasks. However, integrating all these functionalities into a single device, e.g., for simultaneous adaptive wavefront correction and tracking, can significantly increase the size, weight, and power consumption (SWaP) of the final system. In this contribution, we demonstrate the use of the Texas Instruments Phase Light Modulator (PLM) as a low-SWaP, chip-scale solution for simultaneous wavefront correction and beam tracking in real-time, featuring over one million actuators. In particular, we will present and discuss multiple algorithms and optimization strategies that we have specifically developed for PLM-based wavefront correction.
Anton Makarov, Katerina Kozlova, Denis Brazhnikov
et al.
We study a resonant interaction of an elliptically polarized light wave with $^{87}$Rb vapor (D$_1$ line) exposed to a transverse magnetic field. A $5$$\times$$5$$\times$$5$~mm$^3$ glass vapor cell is used for the experiments. The wave intensity is modulated at the frequency $Ω_m$. By scanning $Ω_m$ near the Larmor frequency $Ω_L$, a magnetic resonance (MR) can be observed as a change in the ellipticity parameter of the wave polarization. This method for observing MR allows to significantly improve the signal-to-noise ratio compared to a classical Bell-Bloom scheme using a circularly polarized wave. The sensitivity of the magnetic field sensor is estimated to be $\approx\,$$130$~fT/$\surd$Hz in a $2$~kHz bandwidth, confidently competing with widely used Faraday-rotation Bell-Bloom schemes. The results can be used to develop a miniature all-optical magnetic field sensor for medicine and geophysics.
Surface plasmon enhanced processes and hot-carrier dynamics in plasmonic nanostructures are of great fundamental interest to reveal light-matter interactions at the nanoscale. Using plasmonic tunnel junctions as a platform supporting both electrically- and optically excited localized surface plasmons, we report a much greater (over 1000x) plasmonic light emission at upconverted photon energies under combined electro-optical excitation, compared with electrical or optical excitation separately. Two mechanisms compatible with the form of the observed spectra are interactions of plasmon-induced hot carriers and electronic anti-Stokes Raman scattering. Our measurement results are in excellent agreement with a theoretical model combining electro-optical generation of hot carriers through non-radiative plasmon excitation and hot-carrier relaxation. We also discuss the challenge of distinguishing relative contributions of hot carrier emission and the anti-Stokes electronic Raman process. This observed increase in above-threshold emission in plasmonic systems may open avenues in on-chip nanophotonic switching and hot carrier photocatalysis.
Optical Projection Tomography (OPT) is a powerful tool for 3D imaging of mesoscopic samples, thus of great importance to image whole organs for the study of various disease models in life sciences. OPT is able to achieve resolution at a few tens of microns over a large sample volume of several cubic centimeters. However, the reconstructed OPT images often suffer from artifacts caused by different kinds of physical miscalibration. This work focuses on the refractive index (RI) mismatch between the rotating object and the surrounding medium. We derive a 3D cone beam forward model to approximate the effect of RI mismatch and implement a fast and efficient reconstruction method to correct the induced seagull-shaped artifacts on experimental images of fluorescent beads.
Ultrasound-modulated optical tomography (UOT) is a technique that images optical contrast deep inside scattering media. Heterodyne holography is a promising tool able to detect the UOT tagged photons with high efficiency. In this work, we describe theoretically the detection of the tagged photon in heterodyne holography based UOT, show how to filter the untagged photon, and discuss the effect of shot noise. The discussion considers also speckle decorrelation. We show that optimal detection sensitivity can be reached, if the frame exposure time of the camera used to perform the holographic detection is of the order of the decorrelation time.
We proposed a method to achieve superresolved optical imaging without beating the diffraction limit of light. This is achieved by magnifying the ideal optical image of the object through higher-order spatial frequency generation while keeping the size of the effective point spread function of the optical imaging system unchanged. A proof-of-principle experiment was demonstrated in a modified $4f$-imaging system, where the spatial frequency of a two-line source was doubled or tripled on the confocal Fourier plane of the $4f$-imaging system through a light pulse storage and retrieval process based on the electromagnetically induced transparency effect in a Pr$^{3+}$:$\rm Y_2SiO_5$ crystal, and an originally unresolvable image of the two line sources in the conventional $4f$-imaging system became resolvable with the spatial frequency doubling or tripling. Our results offer an original way towards improving optical imaging resolution without beating the diffraction limit of light, which is totally different from the existing superresolution methods to overcome the diffraction limit.
We demonstrate optically stable amorphous silicon nanowires with both high nonlinear figure of merit (FOM) of ~5 and high nonlinearity Re(γ) = 1200W-1m-1. We observe no degradation in these parameters over the entire course of our experiments including systematic study under operation at 2 W coupled peak power (i.e. ~2GW/cm2) over timescales of at least an hour.
It is shown theoretically that an optical bottle resonator with a nanoscale radius variation can perform a multi-nanosecond long dispersionless delay of light in a nanometer-order bandwidth with minimal losses. Experimentally, a 3 mm long resonator with a 2.8 nm deep semi-parabolic radius variation is fabricated from a 19 micron radius silica fiber with a sub-angstrom precision. In excellent agreement with theory, the resonator exhibits the impedance-matched 2.58 ns (3 bytes) delay of 100 ps pulses with 0.44 dB/ns intrinsic loss. This is a miniature slow light delay line with the record large delay time, record small transmission loss, dispersion, and effective speed of light.
Lida Ebrahimi Zohravi, Azar Vafavard, Mohammad Mahmoudi
The optical properties of a weak probe field in a duplicated two-level system are investigated in multiphoton resonance (MPR) condition and beyond it. It is shown that, by changing the relative phase of applied fields, the absorption switches to the amplification without inversion in MPR condition. By applying the Floquet decomposition to the equation of motion beyond MPR condition, it is shown that the phase-dependent behavior is valid only in MPR condition. Moreover, it is demonstrated that the group velocity of light pulse can be controlled by the intensity of applied fields and the gain-assisted superluminal light propagation (fast light) is obtained in this system. In addition, the optical bistability (OB) behavior of the system is studied beyond MPR condition. We apply an indirect incoherent pumping field to the system and it is found that the group velocity and OB behavior of the system can be controlled by incoherent pumping rate.
Electromagnetically induced transparency (EIT) in metastable helium at room temperature is experimentally shown to exhibit light storage capabilities for intermediate values of the detuning between the coupling and probe beams and the center of the atomic Doppler profiles. An additional phase shift is shown to be imposed to the retrieved pulse of light when the EIT protocol is performed at non-zero optical detunings. The value of this phase shift is measured for different optical detunings between 0 and 2 GHz, and its origin is discussed.
Marco Santagiustina, Luca Schenato, Carlo Giacomo Someda
Efficient slow and fast light fiber devices based on narrow band optical parametric amplification require a strict polarization control of the waves involved in the interaction. The use of high birefringence and spun fibers is studied theoretically, possible impairments evaluated, and design parameters determined.