Design and analysis of optical QAM scheme using an electro-optic microring resonator

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.

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.

Optical frequency combs have been widely used in spectrum analysis, coherent optical communication, and accurate distance measurement. We propose a straightforward method to improve the flatness of optical frequency combs. First, we derived the output of the optical signal for the configuration of a cascaded MZM and two PMs. Second, we identified the parameter value when the flatness was optimal after traversing different parameter spaces. The optimal flatness conditions could be automatically determined from an existing sample dataset by using neural networks and Bayesian optimization, which significantly reduced the calculation cost. Furthermore, a broad spectrum and low power consumption were also achieved. Finally, the generated optical frequency comb signal was divided into eight carriers with 50 GHz intervals, and the optical transmission system was verified by applying a 16-QAM modulation of 40 GBaud/s to each channel. The constellation diagram proved the feasibility of this optical comb generation scheme.

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.

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.

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.

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.

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.

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.

The JCSAT 9 Communications Satellite, developed by Lockheed Martin Commercial Space Systems using an A2100 [1] spacecraft, will use an on-orbit configurable Frequency Generation Unit (FGU) that is SEU hard and total dose tolerant. The spacecraft is due for launch in 2005. The FGU design [2] illustrates the principles and benefits of a single loop synthesizer generating low noise and multiple local oscillators for various frequency (up/down) converters in the payload. Nineteen phase-locked loops are configured to provide coherent, multiple, and redundant C and L band local oscillator frequencies by combining digital, analog and microwave concepts to achieve small size, low mass, low DC power consumption, low phase noise, and spectral purity.

A time domain optical demultiplexer using electrooptic microring resonator is proposed. The switching window with pico-second order width is generated by using a sinusoidal electrical control voltage to shift the refractive index of the material. The modulation characteristics and switching window of the microring resonator are studied. The dependences of the width and extinction ratio of the switching window on the control voltage are analyzed. The demultiplexing performance of a 40–10 Gbps system is evaluated by numerical simulation technology. Results show that switching windows with required width and extinction ratio can be generated.

In conventional computers, wiring between transistors is required to enable the execution of Boolean logic functions. This has resulted in processors in which billions of transistors are physically interconnected, which limits integration densities, gives rise to huge power consumption and restricts processing speeds. A method to eliminate wiring amongst transistors by condensing Boolean logic into a single active element is thus highly desirable. Here, we demonstrate a novel logic architecture using only a single electromechanical parametric resonator into which multiple channels of binary information are encoded as mechanical oscillations at different frequencies. The parametric resonator can mix these channels, resulting in new mechanical oscillation states that enable the construction of AND, OR and XOR logic gates as well as multibit logic circuits. Moreover, the mechanical logic gates and circuits can be executed simultaneously, giving rise to the prospect of a parallel logic processor in just a single mechanical resonator.

A quad, small form-factor pluggable 28 Gbps optical transceiver design scheme is proposed. It is capable of transmitting 50 Gbps of data up to a distance of 40 km using modulation signals with a level-four pulse-amplitude. The proposed scheme is designed using a combination of electro-absorption-modulated lasers, transmitter optical sub-assembly, low-cost positive-intrinsic-native photodiodes, and receiver optical sub-assembly to achieve standard performance and low cost. Moreover, the hardware and firmware design schemes to implement the optical transceiver are presented. The results confirm the effectiveness of the proposed scheme and the performance of the manufactured optical transceiver, thereby confirming its applicability to real industrial sites.

Due to the growing concerns toward green communications, future wireless communications systems should aim at higher data rate with even lower power consumption. Since the power amplifier (PA) is a major power consuming analog component, its efficient use is of primary concern in such green communications framework. Orthogonal frequency division multiplexing (OFDM) is a standard approach for achieving high data rate communications with high reliability, but one of its well-known drawbacks is low PA efficiency caused by its signal with high peak-to-average power ratio (PAPR). The use of iterative clipping and filter (ICF) has been widely studied to reduce peak-to-average ratio (PAPR) so that sufficient usage of PA is achieved, but at a cost of in-band distortion and increasing complexity at the transmitter. In many communication standards, however, there is a constraint in acceptable in-band distortion level and thus the question is how much improvement can one achieve in terms of PA efficiency for a given in-band distortion constraint. In this paper, we investigate the trade-off between amplifier efficiency and distortion for an OFDM system operated with ICF in the long term evolution (LTE) framework, and reveal its limitation when considering the effect of PA that comes after the ICF in a practical circuit.

Deep ultraviolet (DUV) lasers emitting below 300 nm are of great interest for many applications, for instance in medical diagnostics or for detecting biological agents. Established DUV lasers, e.g. gas lasers or frequency quadrupled solid-state lasers, are relatively bulky and have high power consumptions. A compact and reliable laser diode based system emitting in the DUV could help to address applications in environments where a portable and robust light source with low power consumption is needed. In this work, a compact DUV laser system based on single-pass frequency doubling of highpower GaN diode laser emission is presented. A commercially available high-power GaN laser diode from OSRAM Opto Semiconductors serves as a pump source. The laser diode is spectrally stabilized in an external cavity diode laser (ECDL) setup in Littrow configuration. The ECDL system reaches a maximum optical output power of 700 mW, maintaining narrowband emission below 60 pm (FWHM) at 445 nm over the entire operating range. By direct single pass frequency doubling in a BBO crystal with a length of 7.5 mm a maximum DUV output power of 16 μW at a wavelength of 222.5 nm is generated. The presented concept enables compact and efficient diode laser based light sources emitting in the DUV spectral range that are potentially suitable for in situ applications where a small footprint and low power consumption is essential.