Electromagnetically induced transparency with a single optomechanical microring resonator.

We investigate the electromagnetically induced transparency (EIT) in Rb atoms interacting with a pseudothermal probe light exhibiting a Bose–Einstein photon number distribution. The EIT spectrum in the 5S1/2−5P1/2 transition of the Λ-type system of the 87Rb atom was observed using a coupling laser and the pseudothermal probe light generated by passing the probe laser though a rotating rough disk. From the EIT spectrum with pseudothermal light, we experimentally demonstrated that the fluctuation of the number of photons was the same as the superposition of frequency noise of the probe light. The coherence time of the pseudothermal probe light was estimated from the measured EIT spectra. We confirmed that the experimental results as a function of the rotating speed of the rough disk were in good agreement with the numerically calculated results.

The advantage of the study is that nonlinear behavior of light inside ring resonators system can be controlled and managed by using appropriate parameters of the microring resonator (MRR) system. The effects of the coupling coefficients on the bifurcation and chaos behaviors, in terms of roundtrip and output powers are presented. Moreover, the radius of the ring is the key parameter which causes the nonlinear behaviors happen in lower roundtrips. Input optical powers can be in the form of an optical dark/bright soliton or a Gaussian beam. Optical soliton can be used to generate chaotic filter characteristics when propagating within the single microring resonator (SMRR). Therefore, chaotic signals are generated, whereas the required signals including specific wavelengths or frequencies can be used to perform the optical communication. The wide range of spread wavelength can be generated, using proposed MRRs system, where the wavelength multiplexing, dense wavelength division multiplexing (DWDM) can be perform via the optical wireless communication. The proposed MRR systems are suitable for the multi soliton pulses generation, which are available for high performance communication network. Increasing in communication capacity is provided by increasing of soliton pulses, which can be performed by generation of temporal and spatial optical soliton pulses. Generated multi optical soliton can be input into an optical receiver unit which is a quantum processing system used to generate high capacity packet of quantum information within the series of MRRs.

Generation of electromagnetically induced transparency (EIT) and absorption (EIA) effects in optical cavity systems paves a way for many applications ranging from fundamental physics to various photonic applications, such as analogous quantum interference effects, slow light, and light storage. Here, thermal gradient induced transparency (TGIT) and absorption (TGIA) effects in a single microcavity are proposed and demonstrated. The effects originate from the unique temperature gradient in the axial direction of the functionalized microbottle cavity, which leads to different resonance evolutions for whispering gallery modes with different axial orders. Furthermore, this platform is leveraged as a probe to realize a direct temperature readout from the transmission spectrum via multiple TGIT (TGIA is also applicable)‐based photonic barcodes with a high detection resolution of 9 × 10−4 °C. This platform offers a novel, highly efficient, and simple scheme to realize dynamic mode coupling for various applications, such as light storage and temperature detection.

Combining a transfer matrix analysis and slowly varying envelope approximation, we propose a simple method to describe steady states associated with dispersive multistability in coupled microring resonators. This approach allows us to consider nonlinear interactions between independent forward and backward propagative fields. We applied this simple formalism first to decrease the tristability intensity threshold in linearly coupled resonators and second to optically control the tristable behavior in a single microring resonator.

Output optical characteristics of miniature highly stable hybrid integrated lasers were experimentally investigated. The devices are assembled in an industrial form factor using a multi-frequency semiconductor laser coupled with an external microring resonator (MRR). An expression for the coupling coefficient between the laser diode and the ring resonator is derived, taking into account the butt coupling efficiencies and reflection from the MRR. For two lasers with different MRRs the level of low-frequency thermorefractive noise is estimated and the instantaneous linewidth values are calculated and experimentally measured, yielding 200 Hz and 900 Hz, which are comparable to those of best commercially available analogues. The good agreement between theoretical and experimental data confirms the validity of the model used.

In this work we propose a method for on-chip detection of the complex refractive index of the sensing medium at multiple wavelengths for selective sensing. For the optical sensor to be selective, i.e. able to determine the substance present in the medium, either surface functionalization or absorption spectroscopy is often used. Surface functionalization is a complex process and is mainly limited to biological media. On the other hand, absorption spectroscopy is not suitable for on-chip sensing with micrometer dimensions as this will result in poor sensitivity, especially when working far from the substance absorption peaks. Here, we detect the dispersion of both the real n and imaginary k parts of the refractive index which are unique for each substance. This is done using a single micro-ring resonator (MRR) that exhibits multiple resonances over the operating wavelength range. The real and imaginary parts of the medium refractive index are determined at each resonance using the resonance wavelength and the absorption coefficient, respectively. In addition, using this technique the concentration composition of a multi-element medium can be determined by solving a system of linear equations that corresponds to the different wavelengths (resonances). We designed a silicon-on-insulator (SOI) ring-resonator operating in the near-infrared region from λ = 1.46 µm to λ = 1.6 µm. The ring exhibits 11 resonances over the 140 nm operating wavelength range where the corresponding medium refractive index is obtained. This design can detect four different substances namely, methanol, ethanol, propanol, and water. An average error of less than 0.0047% and 1.65% in the detection of the real and imaginary parts, respectively were obtained. Finally, the concentration composition of different multi-element media were successfully determined using the least square method with 97.4% detection accuracy.

In this work, an optical beamforming network (OBFN) is proposed and simulated to verify its effectiveness on a 4 × 4 2D antenna array, enabling efficient beam steering for millimeter-wave systems. The network employs an optical all-pass filter (APF) based on a single micro-ring resonator (MRR) coupled with a straight waveguide for delay control. The APF is designed to achieve a maximum delay of approximately 100 ps in the 28 GHz communication band while maintaining a constant amplitude response during phase adjustment. This design significantly reduces amplitude variations associated with delay control, eliminating the amplitude effects typically observed in conventional MRR-based delay methods. Simulation results demonstrate that the design supports simultaneous lateral and longitudinal beam sweeps from -60° to 60° on a 4 × 4 2D antenna array. This approach offers a high-performance solution for OBFN architectures.

I will review recent progresses on the realization and application of electromagnetically induced transparency in semiconductors. The emphasis will be on the use of electron spin coherence in quantum well structures. Electromagnetically induced transparency (EIT) exploits destructive quantum interference induced by a nonradiative quantum coherence to make an otherwise opaque medium transparent. EIT and EIT-related processes provide a powerful and effective mechanism for controlling and manipulating light. While most EIT studies have thus far been carried out in atomic or atomic-like systems, the basic concept of EIT can also be applied to optical excitations in semiconductors. In this talk, I will discuss recent progresses on EIT studies in semiconductors. There are two major obstacles for realizing EIT and, more generally, for coherent manipulation of quantum coherences in semiconductors. First of all, with the exception of electron spin coherence, quantum coherences in semiconductors are typically short lived and are extremely fragile against dynamic processes such as carrier-carrier and carrier-phonon scattering. Secondly, coherent nonlinear optical processes in semiconductors are profoundly modified by manybody Coulomb interactions between carriers. I will discuss various EIT schemes that have been used to take advantage of the robust electron spin coherence in semiconductors and to harness effects of inherent manybody Coulomb interactions.

The electromagnetically induced transparency (EIT) with a (near-)resonant chaotic (amplitude-phase fluctuating, Gaussian-Markovian) coupling field is studied theoretically. The Fourier transform of the steady-state EIT spectrum, which determines a nonstationary probe absorption, is also considered. This quantity equals the average diagonal element of the (reduced) evolution operator of the coupled transition (the evolution function). The exact solution in the form of a continued fraction is obtained and used to perform numerical calculations. Moreover, a number of approximate analytical results are obtained, which, together with the results of previous publications, describe the EIT and the evolution function in all possible regimes. In particular, in the constructive-interference case the EIT increases with the coupling-field bandwidth ν at sufficiently small ν. For a strong field, the maximum of the transparency as a function of ν is less than that for a monochromatic field of the same average intensity. In contrast, for a weak field, there is a range of ν values, where the field fluctuations do not affect the EIT. The latter result is shown to hold for a broad class of stochastic fields.

We propose an optical 16-QAM generation scheme based on pockel effect induced in a single electro-optic microring resonator by the incoming 4 bit binary data. The design of the resonator for achieving this and the 16-QAM constellation that can be realized is presented. This scheme can provide small footprint and low power consumption with a potential for realizing green elastic optical communication.

A single mode GaInAsP-InP double microring resonator coupled laser is demonstrated for the first time. The laser has an output power of 0.12 mW with a sidemode supression ratio of 30 dB.

We investigate the linear and nonlinear optical response to an optical pumping of a four-level atomic system with electromagnetically induced transparency (EIT) in a cold Rydberg atomic gas. It is found that the transient behavior (especially, the third- and fifth-order susceptibilities) of the probe field, and the steady-state EIT spectrum of the gas, depend crucially on the Rydberg atoms' interaction. Furthermore, we find that the response speed of the Rydberg interaction with EIT can be as much as six times faster than the EIT without the Rydberg interaction, and that the nonlinear response time of the fifth-order optical susceptibility is longer than that of the third-order susceptibility. It is established that the Rydberg blockade effect plays a significant role in increasing the response speed of the Rydberg with EIT.

Well-established electromagnetically induced transparency (EIT) and absorption (EIA) have been applied to various applications including quantum computing, light storage, and precision measurement. Here, we propose and implement a differential detection scheme based on coexisting EIT and EIA signals in a double-Λ system with counterpropagating bichromatic laser fields, in which a differential coherent population trapping (diff-CPT) signal is extracted with a desired enhanced amplitude and highly suppressed common-mode noise. Compared to that of either EIT or EIA, the observed signal-to-noise ratio of the proposed method’s diff-CPT signal improved by one order of magnitude, which would benefit the implementation of high-performance CPT clocks. This technique may also be applied to magnetometers and precision spectroscopy.

We present a new approach for designing a compact microring resonator structure based on only one multimode waveguide, which can provide a very high free spectral range (FSR) and capability of controlling the critical coupling. The silicon on insulator (SOI) waveguide and graphene-silicon waveguide (GSW) are used for the proposed structure. By changing the applied voltage on the graphene sheet, we can achieve a full control of the critical coupling. Some important properties of the proposed microring resonator such as free spectral range and quality factor are analyzed. We show that our structure can provide all characteristics of a single microring resonator with universal applications such as optical switching, modulating, filtering and signal processing, etc.

We present a complementary metal oxide semiconductor (CMOS) process with floating gate field-effect transistors (FG FETs) as sensor inputs for bioelectronic applications. In order to achieve a stable passivation of the devices against electrolyte solutions, we included additional fabrication steps and materials into our advanced process. Main changes to the standard CMOS process were the application of titanium silicide for all interconnects, a passivation layer formed by LPCVD deposition of silicon nitride and oxide, and an oxidation step for the sensing areas exposed to the electrolyte at the end of the fabrication process. Different arrays of FG FETs were fabricated. We present extracellular recordings from rat cardiac myocytes and from genetically modified human embryonic kidney (HEK) cells. The extracellular recordings showed a good signal-to-noise ratio. Due to the design, the chips were robust and showed an excellent long-term stability. They were able to withstand several cleaning procedures and subsequent cell cultures. The CMOS process allowed the implementation of simple integrated circuits. With two 5-bit decoders it was possible to address an array of 32 × 32 FG FETs. Our study paves the way for future fabrication of higher integrated chips with a stable and robust operation when used in bioelectronic applications.