Dispersive tristability in microring resonators

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.

An all-optical realization scheme of electromagnetically induced transparency (EIT) in a single silicon optomechanical microring resonator is proposed and demonstrated. Due to the strong mechanical Kerr effect and well-designed microring resonator, two modes with a resonant frequency separation of 292 GHz (2.35 nm) can be tuned into resonance when the control power is about 4.3 µW, and the EIT spectrum is achieved. Our work provides a constructive solution for realizing EIT in a single microcavity with a low mode density. Furthermore, this device is fully integrated on-chip and compatible with current complementary metal-oxide semiconductor (CMOS) processing and has great potential in applications such as light storage, optical sensing, and quantum optics.

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.

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 have designed and integrated a high density micro-ring resonator and photonic crystal waveguide array for wavelength division multiplexing (WDM) microsystem applications. First, we designed and optimized micro-ring resonators. Using the non-unitary transfer matrix method (NU-TM), we have been able to analyze the transfer characteristics of the micro-ring and micro-racetrack resonator system. The track-length dependence, which is not obvious in the unitary transfer method (U-TM) analysis, is clearly found in the NU-TM analysis. By optimizing the WDM filter characteristics such as FSR (Free Spectral Range) and cross-talk, we have found the optimal dimensions, such as length, of the racetrack resonator. And then for improving the WDM filter characteristics of microring resonator, we have designed bent photonic crystal waveguide. Integrating microring resonator with bent photonic crystal waveguide can offer additional functions such as band pass filtering function.

We propose and demonstrate a novel reconfigurable wavelength-selective reflector for planar lightwave technology based on coupled microring resonators. Narrow-band reflection and strong side-lobe suppression are demonstrated in an optical polymer device using the Vernier effect

Analysis of a coupled microring resonators (CMRR) system made of InGaAsP/InP semiconductor is presented. This analysis exploited the time-domain travelling wave method in order to model the transfer function of the passive CMRR, and incorporated modeling of both passive and active MRRs filters wherein such filters are mostly characterized by their frequency response. Theoretical calculations of the system were performed using Vernier effects analysis, in which the Vernier operation with signal flow graph is a graphical approach for analyzing the intricate photonic circuits mathematically and allows for quick calculation of optical transfer function. Two MRRs, each having a radius of 32 µm, were vertically coupled together and used to generate resonant peaks. Narrow transmission peaks having bandwidths at full width at half maximum (FWHM) of 0.05 nm, corresponding to 6.24 GHz, were generated. The free spectrum range (FSR) of the pulses was 12 nm, which corresponded to 1.5 THz in the frequency domain. The finesse “F” given by FSR/FWHM was ~240, and the Q-factor obtained, which is the ratio of the resonant wavelength to the 3-dB bandwidth (FWHM), was ~3.1 × 104; such results are indicative of the system having a good performance. The dispersion and group delay of the CMRR has been presented as well.

Integrated microring resonators are well suited for wavelength-filtering applications in optical signal processing, and cascaded microring resonators allow flexible filter design in coupled-resonator optical waveguide (CROW) configurations. However, the implementation of high-order cascaded microring resonators with high extinction ratios (ERs) remains challenging owing to stringent fabrication requirements and the need for precise resonator tunability. We present a fully integrated on-chip second-order CROW filter using silicon photonic microelectromechanical systems (MEMS) to adjust tunable directional couplers and a phase shifter using nanoscale mechanical out-of-plane waveguide displacement. The filter can be fully reconfigured with regard to both the ER and center wavelength. We experimentally demonstrated an ER exceeding 25 dB and continuous wavelength tuning across the full free spectral range of 0.123 nm for single microring resonator, and showed reconfigurability in second-order CROW by tuning the ER and resonant wavelength. The tuning energy for an individual silicon photonic MEMS phase shifter or tunable coupler is less than 22 pJ with sub-microwatt static power consumption, which is far better than conventional integrated phase shifters based on other physical modulation mechanisms.

We present a field coupling method for analyzing coupled microring resonators (CMRs) in sheared 2-D lattices. Shearing has the effect of imparting phase shifts to certain coupling elements in the lattice, and is shown to be a simple way for realizing negative couplings in CMR networks. We mathematically show that the operation of shearing can be described by a similarity transformation on the field coupling matrix of the microring network. The analysis presented can be generalized to account for the position dependence of the coupling junctions of arbitrary 2-D CMR networks.

Single microring resonators have been used in applications such as wavelength multicasting and microwave photonics, but the dependence of the free spectral range with ring radius imposes a trade-off between the required GHz optical channel spacing, footprint and power consumption. We demonstrate four-channel all-optical wavelength multicasting using only 1 mW of control power, with converted channel spacing of 40-60 GHz. Our device is based on a compact embedded microring design fabricated on a scalable SOI platform. The coexistence of close resonance spacing and high finesse (205) in a compact footprint is possible due to enhanced quality factors (30,000) resulting from the embedded configuration and the coupling-strength dependence of resonance spacing, instead of ring size. In addition, we discuss the possibility of achieving continuously mode splitting from a single-notch resonance up to 40 GHz.

We use soft lithography replica molding to fabricate unclad polystyrene (PS) and clad SU-8 microring resonator filters. The PS resonator has an intrinsic quality factor of 1.0/spl times/10/sup 4/ at /spl lambda/=1.55 /spl mu/m, while that of the SU-8 resonator is 7100. The extinction ratios of the PS and SU-8 microring filters are -12 and -20 dB, respectively, with net insertion losses of 6.7 and 9.9 dB. The good quality factors and high extinction ratios of the microring resonator filters show the practicality of soft-lithography replica molding for the fabrication of integrated optical devices.

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.