arXiv subjects

Min Xiao

Publications and source records attributed to Min Xiao.

At least 55 records · Page 3Linked to original sources

arXiv2020

Brillouin-Kerr soliton frequency combs in an optical microresonator

By generating a Brillouin laser in an optical microresonator, we realize a soliton Kerr microcomb through exciting the Kerr frequency comb using the generated Brillouin laser in the same cavity. The intracavity Brillouin laser pumping scheme enables us to access the soliton states with a blue-detuned input pump. Due to the ultra-narrow linewidth and the low-noise properties of the generated Brillouin laser, the observed soliton microcomb exhibits narrow-linewidth comb lines and stable repetition rate even by using a diode laser with relatively broad linewidth. Also, we demonstrate a low-noise microwave signal with phase noise levels of -24 dBc/Hz at 10 Hz, -111 dBc/Hz at 10 kHz, and -147 dBc/Hz at 1 MHz offsets for a 11.14 GHz carrier with only a free-running input pump. The easy operation of the Brillouin-Kerr soliton microcomb with excellent performance makes our scheme promising for practical applications.

physics.optics↗

arXiv2020

Optical image decomposition and noise filtering based on Laguerre-Gaussian modes

We propose and experimentally demonstrate an efficient image decomposition in the Laguerre-Gaussian (LG) domain. By developing an advanced computing method, the sampling points are much fewer than those in the existing methods, which can significantly improve the calculation efficiency. The beam waist, azimuthal and radial truncation orders of the LG modes are optimized depending on the image information to be restored. In the experiment, we decompose an image by using about 30000 LG modes and realize a high-fidelity reconstruction. Furthermore, we show image noise reduction through LG domain filtering. Our results open a door for LG-mode based image processing.

eess.IV↗

arXiv2020

Laguerre-Gaussian transform for rotating image processing

Rotation is a common motional form in nature, existing from atoms and molecules, industrial turbines to astronomical objects. However, it still lacks an efficient and reliable method for real-time image processing of a fast-rotating object. Since the Fourier spectrum of a rotating object changes rapidly, the traditional Fourier transform (FT) techniques become extremely complicated and time consuming. Here, we propose a Laguerre-Gaussian (LG) transform to analyze the rotating object with LG-mode basis. The rotation operation provides a feasible way to acquire LG spectrum, which is similar to the function of lens in FT. Particularly, the obtained LG spectrum does not change even the object working at a high rotating speed. By analyzing the LG spectrum, one can perform image processing such as reconstruction, edge enhancement, and pattern replication. Such LG transform provides an efficient and convenient way to real-time monitor and analyze a fast-rotating object in scientific research and industry.

physics.optics↗

arXiv2020

Generations of high efficiency, high purity, and broadband Laguerre-Gaussian modes from a Janus optical parametric oscillator

Laguerre-Gaussian (LG) modes, carrying orbital angular momentum of light, are critical for important applications such as high-capacity optical communications, super-resolution imaging, and multi-dimensional quantum entanglement. Advanced developments in these applications strongly demand reliable and tunable LG mode laser sources, which, however, do not yet exist. Here, we experimentally demonstrate highly-efficient, highly-pure, broadly-tunable, and topological-charge-controllable LG modes from a Janus optical parametric oscillator (OPO). Janus OPO featuring two-face cavity mode is designed to guarantee an efficient evolution from a Gaussian-shaped fundamental pumping mode to a desired LG parametric mode. The output LG mode has a tunable wavelength between 1.5 um and 1.6 um with a conversion efficiency above 15%, a topological charge switchable from -4 to 4, and a mode purity as high as 97%, which provides a high-performance solid-state light source for high-end demands in multi-dimensional multiplexing/demultiplexing, control of spin-orbital coupling between light and atoms, and so on.

physics.optics↗

arXiv2020

Spin-orbit coupling in photonic graphene

We generate experimentally a honeycomb refractive index pattern in an atomic vapor cell using electromagnetically-induced transparency. We study experimentally and theoretically the propagation of polarized light beams in such "photonic graphene". We demonstrate that an effective spin-orbit coupling appears as a correction to the paraxial beam equations because of the strong spatial gradients of the permittivity. It leads to the coupling of spin and angular momentum at the Dirac points of the graphene lattice. Our results suggest that the polarization degree plays an important role in many configurations where it has been previously neglected.

cond-mat.mes-hall↗

arXiv2019

Synchronous oscillations locked on classical energy levels by two cooperating drives

It is intuitively imagined that the energy of a classical object always takes continues values and can hardly be confined to discrete ones like the energy levels of microscopic systems. Here, we demonstrate that such classical energy levels against intuition can be created through a previously unknown synchronization process for nonlinearly coupled macroscopic oscillators driven by two equally strong fields. Given the properly matched frequencies of the two drive fields, the amplitude and phase of an oscillator will be frozen on one of a series of determined trajectories like energy levels, and the phenomenon exists for whatever drive intensity beyond a threshold. Interestingly, the oscillator's motion can be highly sensitive to its initial condition but, unlike the aperiodicity in chaotic motion, it will nonetheless end up on such fixed energy levels. Upon reaching the stability, however, the oscillations on the energy levels are robust against noisy perturbation.

nlin.PS↗

arXiv2019

Observation of Edge Solitons in Photonic Graphene

Edge states emerge in diverse areas of science, offering new opportunities for the development of novel electronic or optoelectronic devices, sound and light propagation controls in acoustics and photonics. Previous experiments on edge states and exploration of topological phases in photonics were carried out mostly in linear regimes, but the current belief is that nonlinearity introduces new striking features into physics of edge states, lead-ing to the formation of edge solitons, optical isolation, and topological lasing, to name a few. Here we experimentally demonstrate edge solitons at the zigzag edge of a reconfigurable photonic graphene lattice created via the effect of electromagneti-cally induced transparency in an atomic vapor cell with controllable nonlinearity . To obtain edge solitons, Raman gain was introduced to compensate strong absorption experienced by the edge state during propagation. Our observations pave the way to ex-perimental exploration of topological photonics on nonlinear, reconfigurable platform.

physics.optics↗

arXiv2019

Transmission Nonreciprocity in a Mutually Coupled Circulating Structure

Breaking Lorentz reciprocity was believed to be a prerequisite for nonreciprocal transmissions of light fields, so the possibility of nonreciprocity by linear optical systems was mostly ignored. We put forward a structure of three mutually coupled microcavities or optical fiber rings to realize optical nonreciprocity. Although its couplings with the fields from two different input ports are constantly equal, such system transmits them nonreciprocally either under the saturation of an optical gain in one of the cavities or with the asymmetric couplings of the circulating fields in different cavities. The structure made up of optical fiber rings can perform nonreciprocal transmissions as a time-independent linear system without breaking Lorentz reciprocity. Optical isolation for inputs simultaneously from two different ports and even approximate optical isolator operations are implementable with the structure.

physics.optics↗

arXiv2019

Quantum Tomography of the Photon-Plasmon Conversion Process in a Metal Hole Array

In the past decades, quantum plasmonics has become an active area due to its potential applications in on-chip plasmonic devices for quantum information processing. However, the fundamental physical process, i.e., how a quantum state of light evolves in the photon-plasmon conversion process, has not been clearly understood. Here, we report a complete characterization of the plasmon-assisted extraordinary optical transmission process through quantum process tomography. By inputting various coherent states to interact with the plasmonic structure and detecting the output states with a homodyne detector, we reconstruct the process tensor of the photon-plasmon conversion process. Both the amplitude and phase information of the process are extracted, which explains the evolution of the quantum-optical state after the coupling with plasmons. Our experimental demonstration constitutes a fundamental block for future on-chip applications of quantum plasmonic circuits.

quant-ph↗

arXiv2019

On-Chip Chiral Single-Photon Interface: Isolation and Unidirectional Emission

Chiral quantum systems have received intensive attention in fundamental physics and applications in quantum information processing including optical isolation and photon unidirectional emission. Here, we design an on-chip emitter-resonator system with strong chiral light-matter interaction for a chiral single-photon interface. The system includes a microring resonator with a strong evanescent field and a near-unity optical chirality along both of the whole outside and inside walls, allowing a strong and chiral coupling of the Whispering-Gallery mode to a quantum emitter. By initializing a quantum dot in a specific spin ground state or shifting the transition energy with a polarization-selective optical Stark effect, we show a broadband optical isolation at the single-photon level over several GHz. Furthermore, a quantum emitter chirally coupling to the microring resonator can emit single photons unidirectionally. Our protocol paves a way to realize multifunctional chiral single-photon interface in on-chip quantum information processing and quantum networks.

quant-ph↗

arXiv2019

Quantum Interference in a Single Perovskite Nanocrystal

Coherent manipulation of the exciton wave function in a single semiconductor colloidal nanocrystal (NC) has been actively pursued in the past decades without any success, mainly due to the bothersome existences of the spectral diffusion and the photoluminescence (PL) blinking effects. Such optical deficiencies can be naturally avoided in the newly-developed colloidal NCs of perovskite CsPbI3, leading to the PL spectrum with a stable intensity at the single-particle level. Meanwhile, from the first-order photon correlation measurement, a PL linewidth smaller than 20 μeV is estimated for the emission state of the neutral excitons in a single CsPbI3 NC. Moreover, a dephasing time of about 10 ps can be extracted from the quantum interference measurement on the absorption state of the charged excitons. This first demonstration of a coherent optical feature will advance single colloidal NCs into the quantum information regime, opening up an alternative yet prospective research direction beyond their traditional applications such as in optoelectronic devices and bioimaging.

cond-mat.mes-hall↗

arXiv2018

Particle-like behavior of topological defects in linear wave packets in photonic graphene

Topological defects, such as quantum vortices, determine the properties of quantum fluids. The study of their properties has been at the center of activity in solid state and BEC communities. On the other hand, the non-trivial behavior of wavepackets, such as the self-accelerating Airy beams, has also been intriguing physicists. Here, we study the formation, evolution, and interaction of optical vortices in wavepackets at the Dirac point in photonic graphene. We show that even in a non-interacting two-component system the topological excitations appearing in a wavepacket can still be considered as "particles", capable of mutual interaction, with their trajectory obeying the laws of dynamics.

physics.optics↗

arXiv2018

Generating controllable Laguerre-Gaussian laser modes through intracavity spin-orbital angular momentum conversion of light

The rapid developments in orbital-angular-momentum-carrying Laguerre-Gaussian (LG0 l) modes in recent years have facilitated progresses in optical communication, micromanipulation and quantum information. However, it is still challenging to efficiently generate bright, pure and selectable LG0 l laser modes in compact devices. Here, we demonstrate a low-threshold solid-state laser that can directly output selected high-purity LG0 l modes with high efficiency and controllability. Spin-orbital angular momentum conversion of light is used to reversibly convert the transverse modes inside cavity and determine the output mode index. The generated LG0 1 and LG0 2 laser modes have purities of ~97% and ~93% and slope efficiencies of ~11% and ~5.1%, respectively. Moreover, our cavity design can be easily extended to produce higher-order Laguerre-Gaussian modes and cylindrical vector beams. Such compact laser configuration features flexible control, low threshold, and robustness, making it a practical tool for applications in super-resolution imaging, high-precision interferometer and quantum correlations.

physics.optics↗

arXiv2018

Parity-time symmetry in optical microcavity systems

Canonical quantum mechanics postulates Hermitian Hamiltonians to ensure real eigenvalues. Counterintuitively, a non-Hermitian Hamiltonian, satisfying combined parity-time (PT) symmetry, could display entirely real spectra above some phase-transition threshold. Such a counterintuitive discovery has aroused extensive theoretical interest in extending canonical quantum theory by including non-Hermitian but PT-symmetric operators in the last two decades. Despite much fundamental theoretical success in the development of PT-symmetric quantum mechanics, an experimental observation of pseudo-Hermiticity remains elusive as these systems with a complex potential seem absent in Nature. But nevertheless, the notion of PT symmetry has highly survived in many other branches of physics including optics, photonics, AMO physics, acoustics, electronic circuits, material science over the past ten years, and others, where a judicious balance of gain and loss constitutes a PT-symmetric system. Here, although we concentrate upon reviewing recent progress on PT symmetry in optical microcavity systems, we also wish to present some new results that may help to accelerate the research in the area. Such compound photonic structures with gain and loss provide a powerful platform for testing various theoretical proposals on PT symmetry, and initiate new possibilities for shaping optical beams and pulses beyond conservative structures. Throughout this article there is an effort to clearly present the physical aspects of PT-symmetry in optical microcavity systems, but mathematical formulations are reduced to the indispensable ones. Readers who prefer strict mathematical treatments should resort to the extensive list of references. Despite the rapid progress on the subject, new ideas and applications of PT symmetry using optical microcavities are still expected in the future.

physics.optics↗

arXiv2018

On-chip optical isolator and nonreciprocal parity-time symmetry induced by stimulated Brillouin scattering

Realization of chip-scale nonreciprocal optics such as isolators and circulators is highly demanding for all-optical signal routing and protection with standard photonics foundry process. Owing to the significant challenge for incorporating magneto-optical materials on chip, the exploration of magnetic-free alternatives has become exceedingly imperative in integrated photonics. Here, we demonstrate a chip-based, tunable all-optical isolator at the telecommunication band based upon bulk stimulated Brillouin scattering (SBS) in a high-Q silica microtoroid resonator. This device exhibits remarkable characteristics over most state-of-the-art implements, including high isolation ratio, no insertion loss, and large working power range. Thanks to the guided acoustic wave and accompanying momentum-conservation condition, SBS also enables us to realize the first nonreciprocal parity-time symmetry in two directly-coupled microresonators. The breach of time-reversal symmetry further makes the design a versatile arena for developing many formidable ultra-compact devices such as unidirectional single-mode Brillouin lasers and supersensitive photonic sensors.

physics.optics↗

arXiv2018

High-order sideband effect with two-level atoms in a shaken optical lattice

The system of cold two-level atoms inside an optical lattice potential has been used to simulate various models encountered in fundamental and condensed-matter physics. When the optical lattice is periodically shaken, some interesting dynamical effects were observed. In this work, by utilizing the ultra-narrow linewidth of the dipole-forbidden transition in $^{87}$Sr atoms loaded in a shaken optical lattice, we reach a new operation regime where the shaking rate is much larger than linewidth of the two-level transition but much smaller than the frequency interval of the harmonic lattice potential, which was not realizable before. Under such unique conditions, an interesting quantum dynamical effect, the high-order sideband effect (HSE), has been experimentally observed. All the results can be well explained by a developed theoretical model with analytical solution. This HSE is governed by different mechanism as the similar phenomenon observed in semiconductors and has unique characteristics.

physics.atom-ph↗

arXiv2017

Parity-time-symmetric optical lattice with alternating gain and loss atomic configurations

Since the spatially extended periodic parity-time (PT) symmetric potential can possess certain unique properties compared to a single PT cell (with only a pair of coupled gain-loss components), various schemes have been proposed to realize periodic PT-symmetric potentials based on optical lattices. Here, we experimentally construct a spatially periodic PT-symmetric optical potential based on gain-loss arrays induced in a coherently-prepared atomic medium. The gain and loss arrays are generated in alternating four-level N-type and three-level $Λ$-type configurations in the same atomic medium, respectively, which do not require discrete diffractions as demonstrated in the previous work [Phys. Rev. Lett. 117, 123601(2016)] and can be easier to realize with more relaxed operating conditions. The dynamical behaviors of the system are investigated by measuring the phase difference between two adjacent gain and loss channels. The demonstrated PT-symmetric optical lattice with easy accessibility and better tunability sets a new stage for further exploiting the peculiar physical properties in periodic non-Hermitian systems.

physics.optics↗

arXiv2017

Mass sensing by detecting the quadrature of a coupled light field

Ultrasensitive detections have been proposed as an application of optomechanical systems. Here we develop an approach to mass sensing by comparing the detected quadratures of light field coupled to a mechanical resonator, whose slight change of the mass should be precisely measured. The change in the mass of the mechanical resonator will cause the detectable difference in the evolved quadrature of the light field, to which the mechanical oscillator is coupled. It is shown that the ultra-small change $Δm$ from a mass $m$ can be detected up to the ratio $Δm/m\sim 10^{-8}-10^{-7}$ by choosing the feasible system parameters.

quant-ph↗