Ultrafast reversible photoconductivity in 2D MoTe2/Pt van der Waals heterostructure

Transfer and conversion of images between different wavelengths or polarization has significant applications in optical communication and quantum information processing. We demonstrated the transfer of images based on electromagnetically induced transparency (EIT) in a rubidium vapor cell. In experiments, a 2D image generated by a spatial light modulator is used as a coupling field, and a plane wave served as a signal field. We found that the image carried by coupling field could be transferred to that carried by signal field, and the spatial patterns of transferred image are much better than that of the initial image. It also could be much smaller than that determined by the diffraction limit of the optical system. We also studied the subdiffraction propagation for the transferred image. Our results may have applications in quantum interference lithography and coherent Raman spectroscopy.

We propose a scheme of an all-optical transistor based on a coupled Bose-Einstein condensate cavity system. The calculated results show that, in such an optomechanical system, the transmission of the probe beam is strongly dependent on the optical pump power. Therefore, the optical pump field can serve as a ``gate'' field of the transistor, effectively controlling the propagation of the probe field (the ``signal'' field). The scheme proposed here may have potential applications in optical communication and quantum information processing.

We investigate the coherent control of dressing interaction in four-wave mixing (FWM) in a Y-type four-level atomic system based on the dressed states theory. We study the density matrix equation acted by two dressing fields simultaneously governing FWM signal intensity and the eigenvalues under the dressed state formalism. It is shown that the peak position and intensity of Autler–Townes splitting both originate from the dressing interaction as the detuning of the probe field is scanned. Moreover, it is observed that the interaction could be controlled by the dressing fields. Such flexibly controlled nonlinear signal has potential applications in optical communication and quantum information processing.

In an optical vortex beam, each photon carries orbital angular momentum (OAM), a useful resource for applications in optical communication and quantum information processing. The authors demonstrate a diffractive bifocal vortex lens that generates and sorts light beams of different OAM, by means of polarization control. Placing the lens inside a cavity, a vortex-beam laser with a chosen OAM can be realized. Moreover, the lens's OAM sorting can be used in a multifocal optical-trapping system that facilitates the manipulation of nanoparticles, molecules, and biological samples.

We study the controllable optical response in a three-mode optomechanical system comprised of two indirectly coupled cavity modes and an intermediate mechanical mode. The two cavity modes are assumed to have different frequencies and driven by two control fields on the red and blue sidebands, respectively. When the system is perturbed by two probe fields satisfying the specific matching condition, a series of intriguing phenomena can be observed by adjusting phases and amplitudes of the control fields, such as absorption-amplification switching, ultra-narrow response windows, frequency-independent perfect reflection, and ultralong optical group delay. We also compare our system with conventional optomechanical systems to highlight its distinct features. Our results may have potential applications in optical communication and quantum information processing.

Dependence of electromagnetically induced transparency on pressure and temperature in a quantum dot with flat cylindrical geometry

We identify a process in which we can control the behavior of an atomic medium to switch between transparent and enhanced-absorption at multiple frequencies. The process relies on the quantum interference between multiple dark states, which can be constructive or destructive at different frequencies and can be altered dramatically by changing the phase difference between the two circularly polarized components of a single coherent field. This phase-controlled switching behavior is obtainable without altering the powers or frequency detunings of the beams. We demonstrate the process experimentally by using two coherent fields and atomic rubidium vapor. Such selective switching between multiple frequency channels could also have applications in optical communication and quantum information processing.

For the first time, we experimentally study the phase control of the coexisting dressed probe signal, six-wave mixing and fluorescence signals in a five-level K-type atomic system by adjusting the angle between the probe signal and certain coupling beams. Such phase controlling results in a switch between bright and dark states. In addition, by using different hyperfine levels of the K-type atomic system as the ground state, the magnitude of the dressing effect is manipulated. The mechanisms of the three types of nonlinear processes are investigated by changing the frequency detuning and powers of the coupling laser beams. In addition, we study the interference and competition among the involved beams in nonlinear optical processes. Such controllable nonlinear processes could have potential applications in optical communication and quantum information processing.

We first investigate the phase control of the switch between bright and dark states in the transmitted probe, four-wave mixing (FWM) and fluorescence signals in a four-level 85Rb atomic system. With the relative phase modulated from 0 to −π, pure dark state in the FWM and fluorescence channels can be switched to pure bright state, corresponding to the switch from electromagnetically induced transparency to electromagnetically induced absorption. Meanwhile, the results could be obtained in solid crystals. Such phase controlled switch could have potential applications in optical communication and quantum information processing.

Two-dimensional optical gap solitons and vortices in a coherent atomic ensemble loaded on optical lattices

Perfect optical vortex beams (POVBs) carrying orbital angular momentum (OAM) possess annular intensity profiles that are independent of the topological charge. Unlike POVBs, perfect vectorial vortex beams (PVVBs) not only carry orbital angular momentum but also exhibit spin angular momentum (SAM). By incorporating a Dammann vortex grating (DVG) on an all-dielectric metasurface, we demonstrate an approach to create a pair of PVVBs on a hybrid-order Poincaré sphere. Benefiting flexible phase modulation, by engineering the DVG and changing the input-beam state we are able to freely tailor the topological OAM and polarization eigenstates of the output PVVBs. This work demonstrates a versatile flat-optics platform for high-quality PVVB generation and may pave the way for applications in optical communication and quantum information processing.

We explore a single degenerate optical cavity supporting a synthetic two-dimensional space, which includes the frequency and the orbital angular momentum (OAM) axes of light. We create the effective gauge potential inside this synthetic space and show that the system exhibits topologically protected one-way edge states along the OAM axis at the boundaries of the frequency dimension. In this synthetic space, we present a robust generation and manipulation of entanglement between the frequency and OAM of photons. Our Letter shows that a higher-dimensional synthetic space involving multiple degrees of freedom of light can be achieved in a "zero-dimensional" spatial structure, pointing towards a unique platform to explore topological photonics and to realize potential applications in optical communications and quantum information processing.

We present a compact optical delay line (ODL) with wide-range continuous tunability on thin-film lithium niobate (TFLN) platform. The proposed device integrates an unbalanced Mach-Zehnder interferometer (MZI) architecture with dual tunable couplers, where each coupler comprises two 2×2 multimode interferometers (MMIs) and a MZI phase-tuning section. Experimental results demonstrate continuous delay tuning from 0 to 293 ps through synchronized control of coupling coefficients, corresponding to a 4-cm path difference between interferometer arms. The measured delay range exhibits excellent agreement with theoretical predictions derived from ODL waveguide parameters. This result addresses critical challenges in integrated photonic systems that require precise temporal control, particularly for applications in optical communications and quantum information processing, where a wide tuning range is paramount.

Controllable optical effects in Landau-quantized graphene

We demonstrate Autler-Townes (AT) splitting of four-wave mixing in an electromagnetically induced transparency window, which results from the destructive interference between a three-photon process and a five-photon process. The primary and secondary AT splittings are achieved via induced atomic coherence in a four-level Y-type atomic system. Theoretical calculations fit well with the experimentally measured results. Such controlled multichannel splitting of nonlinear optical signals can have potential applications in optical communication and quantum information processing.