Probe Transmission Spectrum Research Articles

Multiple optomechanically induced transparency generated slow light in an array of optomechanical system

We present an array of optomechanical systems which consist of an optical cavity and three nanomechanical resonators. Introducing Jaynes-Cumming (J-C) coupling in the nearest neighbor resonator allows for the formation of optomechanical systems with arrays of N nanomechanical resonators. Using a strong pump field and a weak probe field to drive the optical cavity simultaneously, we investigated the coherent optical response and the probe transmission spectrum manifested as multiple optomechanically induced transparency. We illustrate the impact of probe-cavity detuning, J-C coupling strength, and the number of nanomechanical resonators on the transparent window. In particular, we analyze nanomechanical resonators and find that increasing their number results in multiple transparent windows and slow light at different frequencies. We also find that the slow light effect can be enhanced by increasing the number of nanomechanical resonators with odd numbers at resonance. These findings imply that the arrays of optomechanical system can be used for multichannel optical communications and multichannel quantum information processing.

Light shift induced modification of electromagnetically induced resonances in atomic vapor

We investigate the effects of a third laser on the electromagnetically induced transparency (EIT) spectrum obtained for the D2 line of 87Rb. The third laser converts a typical bi-chromatic laser-induced Λ type system into a four-level N type system. Our work considers two different configurations of N type system depending on whether the third laser is co-propagating or counter-propagating with respect to the other two. The effects of detuning on the EIT spectrum for both cases of N type systems have been experimentally studied. Our results demonstrate that for the counter-propagating case variation of detuning induces a switch from absorption to transmission. We interpret the experimental observations in terms of modification of light shifts by Doppler averaging within a dressed state formalism. Numerical results obtained using the density matrix formulation, which is in good agreement with the experimental results are also included to substantiate the experimental findings. We also find that in the presence of a magnetic field, due to the formation of certain subsystems that involves Zeeman sublevels, neither absorption nor transmission is observed in the probe transmission spectrum. We define these as the “missing resonance” peaks. We propose methods for recovering these peaks in the probe transmission spectrum.

Slow light effect caused by optomechanically induced transparency in multimode optomechanical system

Owing to the radiation pressure, the cavity optomechanical system can couple the optical field with the mechanical resonator, so the state of the mechanical resonator can be regulated through the optical field. Conversely, the optical field in the optomechanical system can also be regulated by modulating the mechanical element. Therefore, many interesting optical phenomena, such as Fano resonance, optomechanically induced absorption and amplification, and optomechanically induced transparency, can be generated in a cavity optomechanical system. Especially in transparent windows, both absorption and dispersion properties change strongly, which results in extensive applications such as slow light and optical storage. Because of its ultra-high quality factor, small size, mass production on chip and convenient all-optical control, it provides an ideal platform for realizing slow light engineering. In this work, by solving the Heisenberg equation of motion of a multimode optomechanical system composed of an optical cavity and two mechanical oscillators, and then by using the input-output relationship for the cavity, the intensity of probe transmission can be obtained. Taking the experimental date as realistic parameters, the behaviors of probe transmission in different detuning conditions are presented. By controlling the pump power under blue detuning, the probe transmission undergoes a process of optomechanically induced absorption to parametric amplification, and the critical pump power is obtained. In the case of red detuning, optomechanically induced transparency, Fano resonance and phase dispersion of the system are studied, and the results of different mechanical coupling strengths, frequency relations and detuning are compared. The numerical results show that as the mechanical coupling strength between two mechanical oscillators increases, the splitting distance becomes larger, and a larger coupling strength ratio will result in a larger splitting peak width. By controlling the frequency relationship between the two resonators, the probe transmission spectra undergo a series of transitions from Fano resonance to optomechanically induced transparency. Because the transmission window of the probe light is accompanied by rapid phase dispersion change, it will lead to group delay. The slow light effect caused by optomechanically induced transparency is further discussed, and the propagation of fast and slow light can be controlled by pump-cavity detuning. The optical delay in this system can be in the order of milliseconds. The multimode optomechanical system based on array structure has a potential application prospect in slowing and storing light pulses.

Observation of stochastic resonance in directed propagation of cold atoms

Randomly diffusing atoms confined in a dissipative optical lattice are illuminated by a weak probe of light. The probe transmission spectrum reveals directed atomic propagation that occurs perpendicular to the direction of probe beam propagation. Resonant enhancement of this directed propagation is observed as we vary the random photon scattering rate. We experimentally characterize this stochastic resonance as a function of probe intensity and lattice well depth. A simple model reveals how the probe-excited atomic density waves and optical pumping rates conspire to create directed atomic propagation within a randomly diffusing sample.

Observation of oscillatory Raman gain associated with two-photon Rabi oscillations of nanofiber-coupled atoms

Quantum emitters with a Λ-type level structure enable numerous protocols and applications in quantum science and technology. Understanding and controlling their dynamics is, therefore, one of the central research topics in quantum optics. Here, we drive two-photon Rabi oscillations between the two ground states of cesium atoms and observe the associated oscillatory Raman gain and absorption that stems from the atom-mediated coherent photon exchange between the two drive fields. The atoms are efficiently and homogeneously coupled with the probe field by means of a nanofiber-based optical interface. We study the dependence of the two-photon Rabi frequency on the system parameters and observe Autler–Townes splitting in the probe transmission spectrum. Beyond shedding light on the fundamental processes underlying two-photon Rabi oscillations, our method could also be used to investigate (quantum) correlations between the two drive fields as well as the dynamical establishment of electromagnetically induced transparency.

Spatial-dependent probe transmission based high-precision two-dimensional atomic localization

Herein, we propose a scheme for the realization of two-dimensional atomic localization in a λ-type three-level atomic medium such that the atom interacts with the two orthogonal standing-wave fields and a probe field. Because of the spatially dependent atom-field interaction, the information about the position of the atom can be obtained by monitoring the probe transmission spectra of the weak probe field for the first time. A single and double sharp localized peaks are observed in the one-wavelength domain. We have theoretically archived high-resolution and high-precision atomic localization within a region smaller than λ/25 × λ/25. The results may have potential applications in the field of nano-lithography and advance laser cooling technology.

Ultrasensitive and high resolution mass sensor by photonic-molecule optomechanics with phonon pump

Whispering gallery mode cavities, due to their high quality factors, small mode volumes, and simple fabrications, have potential applications in photonic devices and ultrasensitive mass sensing. Cavity optomechanic systems based on whispering gallery mode cavities have draw tremendous attention in recent years due to the fact that they reveal and explore fundamental quantum physics and pave the way for potential applications of optomechanical devices. Unfortunately, whispering gallery mode based cavity optomechanics still lies in a single optical mode coupled to a single mechanical mode. Here, in this work, we propose an ultrasensitive and high resolution optical mass sensor by photonic-molecule optomechanics driven by two-tone field, where the optomechanical cavity driven by a weak coherent phonon pump is coupled to an auxiliary optical cavity. The auxiliary cavity plays the role of decreasing the mechanical damping rate while the weak coherent phonon pump to the mechanical mode will improve the intensity of the probe transmission spectrum, which together enhance the mass sensitivity. Compared with the optical mass sensor based on single-cavity optomechanics, the mass sensitivity presented here is improved significantly. We also investigate different parameter regimes which guide us to choose the optimal parameters. Finally, we illustrate the accurate measurement for the mass of nanoparticles, and the photonic-molecule optomechanics system will provide a new platform for exploring the on-chip applications in ultrahigh resolution sensing devices.

Tunable fast to slow light and second-order sideband generation in an optomechanical system with phonon pump

We theoretically demonstrate optomechanically induced transparency (OMIT) and its related coherent optical propagation properties such as fast and slow light effects in a cavity optomechanical system driven by a weak coherent phonon pump for suitable parametric and detuning regimes. The probe transmission spectrum experiences different processes under different detuning regimes, and the numerical simulations indicating a tunable and controllable fast-to-slow light propagation can be achieved by controlling the driving amplitudes and phase of the phonon pump. Further, the second-order sideband (SOS) generation is also demonstrated in the system, and it is found that the efficiency of the SOS generation can be significantly enhanced with manipulating the phonon pump in the resonance regime with numerical simulations. More interestingly, the SOS generation is also sensitive to the detuning (the off-resonance regime), and a robust SOS can be induced and the efficiency of the SOS generation even presents mode splitting which is similar to the linear OMIT. These results lead to good tunability of SOS generation and may find applications in manipulation of light propagation.

Controllable and tunable multiple optomechanically induced transparency and Fano resonance mediated by different mechanical resonators

We demonstrate the multiple optomechanically induced transparency (OMIT) and Fano resonance in a hybrid optomechanical system, in which an optical cavity is coupled to two mechanical resonators with interaction (such as Coulomb interaction) via radiation pressure. The probe transmission spectra experience the transition from single-mode OMIT to multiple OMIT with controlling the interaction of the two resonators, and we discuss the robustness of the system against the cavity decay rate. Compared with the situation of without considering the interaction of the two resonators, the transmission spectra present asymmetric Fano line shapes via manipulating the optomechanical coupling strengths between the optical cavity and the two resonators with taking into account the resonator interaction. Furthermore, we compare the results of identical mechanical resonators with the same mass and frequencies to different mechanical resonators with different mass and frequencies. The results indicate that the probe transmission spectra undergo a series of transition from Fano resonances to OMIT by controlling the different mechanical resonators as well as the interaction between the two mechanical resonators, and we can present a scheme to determine the resonator interaction via measuring the peaks splitting. Finally, the transparency windows in the probe transmission spectrum are accompanied by the rapid normal phase dispersion under different mechanical resonators, which may indicate the slow and fast light effect.

Tunable subluminal and superluminal light with optomechanical-induced transparency under steady-state configuration

We study a two-cavity optomechanical system in which one cavity (A) encloses a mechanical resonator and the other cavity (C) encloses a two-level atom are, respectively, driven by a strong pump and a weak probe fields. In addition to a direct pathway, the excitations in cavity C and the enclosed atom can also be caused through an indirect pathway. The interference between the two possible routs for excitations produces a controllable transparency window in the probe transmission spectrum of cavity C. The coupling strength between cavity C and the atom works as an additional parameter to the coupling strength between the two cavities which helps to manipulate the dynamical properties of the system and hence to control the width of the transparency window. Furthermore, we show that the single setup can be used to produce an optical switch from two different physical behaviors of the model, and to realize subluminal and superluminal behaviors in the output spectrum at probe frequency of cavity C.

Tunable optical amplification arising from blue detuning in a quadratically coupled optomechanical system

We discuss theoretically tunable optical amplification in a quadratically coupled optomechanical system in which two different cavity modes have been excited by two strong optical fields with different frequencies. We find that if cavity mode 1 is driven by the strong control field on red detuning, while cavity mode 2 is excited by the other strong control field on blue detuning, then the amplification of the output probe optical field can occur. On the contrary, when two cavity modes are driven by two strong control fields and both are in the red-detuned regime, the dissipation of the output probe field can occur. The characters of the amplification of the output probe field arising from blue detuning of the control field are analyzed. It is shown that the amplification of the output probe field can be adjusted by the strength of the control field under two-phonon resonance condition. In addition, we also find that the reflectivity of the membrane has a significant impact on the probe transmission spectrum. The amplification of the output probe field may have potential applications for quantum communication, optical complex technology, and all-optical networks.

Dinitrogen Coupling to a Terpyridine-Molybdenum Chromophore Is Switched on by Fermi Resonance

Summary The traditional view of a chemical change is inherently local and classical, and such a change relies on a mix of thermodynamic and kinetic parameters to control reactivity. Often, the thermodynamic stability of chemical bonds necessitates significant energy input for activation. One fundamental question is potentially transformative: can quantum mechanics enable selective bond activation? A possible approach involves strategic input of energy to reaction-specific vibrational levels. Toward this goal, our work describes the coupling of vibrational motions in a terpyridine-molybdenum complex hosting a nonreactive substrate—dinitrogen. Ultrafast coherence spectroscopies revealed a Fermi-resonance coupling mechanism connecting in-plane breathing motion of the light-harvesting terpyridines with the stretching motion of the spatially disparate dinitrogen bridge. Notably, the coupling is significantly enhanced in the photoexcited state. This Fermi resonance indicates an energy conduit that drives the two motions in sync and thereby amplifies vibrational energy exchange. Achieving selective bond activation by bridging vibrations could present a quantum-inspired design principle in synthetic chemistry.

Mass Detection of Single Viruses Based on Whispering Gallery Modes of Optomechanical Systems via Optical Pump–Probe Technique

Whispering gallery modes (WGMs), due to their high quality factors, small mode volumes and simple fabrications, have potential applications especially in sensing. In this work, we theoretically propose a mass sensor based on a realistic cavity optomechanical system (such as in Weis et al., Science 330, 1520 [2010]) in the presence of a strong pump laser and a weak probe laser. The mass of external bioparticles (such as smallpox virus and influenza virus) landing onto WGM cavity can be detected accurately via the probe transmission spectrum. Furthermore, based on this scheme one can even determine a single virus mass via monitoring the half-linewidth of the probe transmission spectrum. Through detecting the virus mass, one may identify the kinds of different viruses.

Fano resonance and slow light in hybrid optomechanics mediated by a two-level system

We study the Fano resonance and slow light in a hybrid optomechanical system, where a mechanical resonator is coupled to a cavity via radiation pressure and to a two-level system (qubit) via the Jaynes-Cummings coupling. The absorption spectra of the weak probe field can exhibit a series of asymmetric Fano line shapes when the frequency of the strong control field varies. The positions of the double Fano resonances can be determined by the cavity--control-field detuning, the qubit-resonator coupling strength, and the transition frequency of the qubit. Furthermore, the transparency windows in the probe transmission spectrum are accompanied by the rapid normal phase dispersion, which indicates the slow light effect. We find that the group delay of the transmitted probe field can be tuned by the frequency and amplitude of the control field and is inversely proportional to the decay rate of the qubit.

Nonvolatile optical memory via recoil-induced resonance in a pure two-level system

We report on the storage of light via the phenomenon of recoil-induced resonance in a pure two- level system of cold cesium atoms. We use a strong coupling beam and a weak probe beam to couple different external momentum states of the cesium atom via two-photon Raman interaction which leads to the storage of the optical information of the probe beam. We have also measured the probe transmission spectrum, as well as the light storage spectrum which reveals very narrow subnatural resonance features showing absorption and gain. We have demonstrated that this memory presents the unique property of being insensitive to the reading process, which does not destroy the stored information leading to a memory lifetime limited only by the atomic thermal motion.

Light storage and cavity supermodes in two coupled optomechanical cavities

We theoretically investigate a hybrid optomechanical system including two coupled optomechanical cavities in the presence of two strong pump fields and a weak probe field. The photon-hopping coupling of the cavities gives rise to two cavity supermodes whose resonant frequencies can be obtained in the probe transmission spectrum. In a strong photon-hopping coupling regime, there is a large coupling rate between the probe field and one of the two cavity supermodes that is called a bright mode. The optomechanical couplings between the bright mode and two mechanical resonators can cause double optomechanically induced transparency (OMIT), which can be employed to both separately and simultaneously store two weak probe pulses with different central frequencies. We obtain the group delay (light storage time) of the probe field in the hybrid optomechanical system. The results suggest that compared with that of a single cavity optomechanical system, the maximum value of the storage time roughly quadrupled in a particular case. The physical origin of the results is discussed. The hybrid optomechanical system opens an avenue of light storage in cavity optomechanics.

Phase-dependent multiple optomechanically induced absorption in multimode optomechanical systems with mechanical driving

We investigate theoretically the response of the output field from an optomechanical system consisting of $N$ nearly degenerate mechanical resonators each coupled to a common cavity mode. When the cavity is driven simultaneously by a strong control field and a weak probe field and each mechanical resonator is driven by a coherent mechanical pump, we obtain the analytical expression for the probe transmission. We show that the probe transmission spectrum can exhibit multiple optomechanically induced absorption (OMIA) with at most $N$ narrow absorption dips, which can be tuned by the phase and amplitude of the mechanical driving field as well as the control field. Moreover, it is shown that the peak probe transmission can be enhanced or suppressed by increasing the amplitude of the mechanical pump, which depends on the phase difference. This phase-dependent effect plays an important role in controlling the propagation of the probe field between OMIA and parametric amplification.

Coherent optical propagation and ultrahigh resolution mass sensor based on photonic molecules optomechanics

We theoretically demonstrate the coherent optical propagation properties based on a photonic molecules optomechanics. With choosing a suitable detuning of the pump field from optomechanical cavity resonance, both the slow- and fast-light effect of the probe field appear in the system. The coupling strength of the two cavities play a key role, which affords a quantum channel and influences the width of the transparency window. Based on the photonic molecules optomechanical system, a high resolution mass sensor is also proposed. The mass of external nanoparticles deposited onto the cavity can be measured straightforward via tracking the mechanical resonance frequency shifts due to mass changes in the probe transmission spectrum. Compared with the single-cavity optomechanics mass sensors, the mass resolution is improved significantly due to the cavity–cavity coupling. The photonic molecules optomechanics provide a new platform for on-chip applications in quantum information processing and ultrahigh resolution sensor devices.

Effective terahertz signal detection via electromagnetically induced transparency in graphene

We propose and analyze an efficient way to detect the terahertz (THz) signal in a magnetized graphene system via electromagnetically induced transparency. Such a scheme for THz signal detection mainly relies on the measurement of probe transmission spectra, in which the behaviors of a weak-probe transmission spectra can be controlled by switching on/off the THz signal radiation. Taking into account the tunable optical transition frequency between the Landau levels in graphene, our analytical results demonstrate that a broad frequency bandwidth of the THz signal radiation, ranging from 0.36 to 11.4 THz, can be inspected and modulated by means of an external magnetic field. As a consequence, the proposed magnetized graphene system performs a striking potential to utilize quantum interference in the design of optical solid-state devices.

Coherent optical propagation properties and ultrahigh resolution mass sensing based on double whispering gallery modes cavity optomechanics

Whispering gallery mode (WGM) cavities due to their high quality factors, small mode volumes, and simple fabrications, have potential applications in photonic devices and ultrasensitive mass sensing. Cavity optomechanic systems based on WGM cavities have progressed enormously in recent years due to the fact that they reveal and explore fundamental quantum physics and pave the way for potential applications of optomechanical devices. However, WGM based cavity optomechanics still lies in a single optical mode coupled to a single mechanical mode. Here in this paper, in order to reveal more quantum phenomena and realize remarkable applications, we present a typical multimode cavity optomechanical system composed of two WGM cavities, of which one WGM cavity is an optomechanical cavity driven by a pump laser and a probe laser and the other cavity is an ordinary WGM cavity only driven with a pump laser. The two WGM cavities are coupled with each other via exchanging energy, and the coupling strength depends on the distance between the two cavities. With the standard method of quantum optics and the quantum Langevin equations, the coherent optical spectra are derived. The coherent optical propagation properties and the phenomenon of optomechanically induced transparency based slow-light effect are demonstrated theoretically via manipulating the coupling strength of the two cavities. The results based on the two-WGM cavity optomechanical system are also compared with those based on the single cavity optomechanical system, and the results indicate that the cavity-cavity coupling plays a key role in the system, which indicates a quantum channel, and influences the width of the transparency window. We further theoretically propose a mass sensor based on the double WGM cavity optomechanical system. To implement mass sensing, the first step is to determine the original frequency of the resonator. With adjusting the detuning parameters and the cavity-cavity coupling strength, a straightforward method to measure the resonance frequency of the WGM optomechanical resonator is proposed. The resonance frequency of the mechanical resonator can be determined from the probe transmission spectrum, and the coupling strength between the two cavities will enhance both the line width and the intensity, which will be beneficial to implementing mass sensing. The mass of external nanoparticles deposited onto the WGM optomechanical cavity can be measured conveniently by tracking the mechanical resonance frequency shifts due to the fact that mass changes in the probe transmission spectrum. Compared with those of single-cavity optomechanical mass sensors, the mass sensitivity and resolution are improved significantly due to the cavity-cavity coupling. This double WGM cavity optomechanical system provides a new platform for exploring the on-chip applications in optical storage and ultrahigh resolution sensing devices.