Optoelectronic Oscillator Research Articles

Joint radar and communication system based on a chaotic optoelectronic oscillator

We present a novel joint radar and communication (JRC) system that utilizes a chaotic optoelectronic oscillator (OEO) to generate a wideband radio frequency carrier. By mixing the carrier with an on-off keying (OOK) signal through intensity modulation and direct detection, a wideband JRC waveform is generated. One part of the waveform is used for transmitting, while the other serves as a reference for radar reception. The unique properties of the chaotic OEO signal, such as its randomness and large bandwidth, are leveraged to achieve superior system performance and eliminate the need for an electronic arbitrary waveform generator. In the proof-of-concept experiment, the JRC system achieves a radar range resolution of 7 cm and a wireless communication rate of 125 Mbit/s.

A Symmetric Parity–Time Coupled Optoelectronic Oscillator Using a Polarization–Dependent Spatial Structure

We propose and experimentally investigate a symmetric parity-time (PT) coupled optoelectronic oscillator (COEO) based on a polarization-dependent spatial structure. In such a COEO system, the gain/loss and coupling coefficients of two orthogonal polarization optical waves can be controlled by adjusting the polarization controller (PC) and the bias voltage of a Mach-Zehnder modulator (MZM). The single-mode selection of a microwave signal can be implemented by the PT symmetry breaking of a special mode. The performance of the proposed COEO is experimentally examined, and a 10.0 GHz microwave signal with a phase noise of −109.1 dBc/Hz @ 10 kHz and a side mode suppression ratio of 51.4 dB is generated. Moreover, an optical frequency comb with a comb tooth spacing of 10.0 GHz and a bandwidth of 100 GHz within a 10 dB amplitude variation can be simultaneously generated.

High-precision magnetic field sensor via optoelectronic oscillator having taper-based in-line modal interferometer

High-precision magnetic field sensor via optoelectronic oscillator having taper-based in-line modal interferometer

A Continuously-Tunable Optoelectronic Oscillator With Full Locking Range Utilizing Three Frequency Tuning Mechanisms

A Continuously-Tunable Optoelectronic Oscillator With Full Locking Range Utilizing Three Frequency Tuning Mechanisms

Enhancing long-term frequency stability of a single-mode optoelectronic oscillator based on phase conjugation.

We propose and experimentally demonstrate what we believe to be a novel single-mode optoelectronic oscillator (OEO) with low frequency drift based on phase conjugation. The long-term frequency stabilization of the OEO is achieved by using photonic microwave phase-conjugate passive compensation. Besides, since there happens to be a nonlinear coupled double loop structure in the OEO, single-mode oscillation can be achieved. The experimental results show that the side mode suppression ratio (SMSR) of the radio frequency (RF) signal from the OEO at 9.93 GHz is enhanced from 5 dB to 68 dB after side mode suppression, and the maximum frequency drift within 600 s reduced from 1.51 ppm to 0.04 ppm, optimized by a factor of about 40. The OEO has a simple structure, no external injection, and the phase noise is not limited by the injected signal.

Dual-loop fourier domain mode-locked optoelectronic oscillator based on three-section mutual-injection integrated semiconductor laser

A directly-modulated Fourier domain mode-locked optoelectronic oscillator (FDML_OEO) based on three-section mutual-injection integrated semiconductor laser (TS_MIISL) with dual-loop feedback structure is proposed and experimentally demonstrated in this paper. By driving the TS_MIISL to work under the period-one (P1) state and modulating the TS_MIISL with low-repetition-rate sawtooth drive signal, a linear frequency-modulated (LFM) signal can be generated. Through adjusting the delay time of the feedback loops to match with the time duration of drive signal, the LFM signal can be significantly optimized in terms of spectral purity. In such a proposed FDML_OEO, no external modulator, polarization controller (PC) and filter are utilized, leading to an outstanding advantage in terms of stable performance and compact structure. The high-purity LFM signal with center frequency and bandwidth of 14 GHz and 8 GHz is obtained. The maximum time-bandwidth product (TBWP) of generated LFM signal could reach up to 48800. Due to the introduction of dual feedback loop, the frequency comb contrast and linewidth could reach up to 45 dB and 5 kHz, respectively. The center frequency and bandwidth of the generated signals are both tunable. A demonstration is made to prove that the pre-compensation processing could improve the linearity of LFM signals.

Generation of Phase-Coded LFM Signals Based on Fourier Domain Mode-Locked Optoelectronic Oscillator

Phase-coded linearly frequency modulated (LFM) signals play essential roles in enhancing the performance of radar as well as exploring wireless communication. To generate phase-coded LFM signals, we propose to launch a phase-coded signal into an optoelectronic oscillator (OEO). When the OEO is Fourier domain mode-locked (FDML), a phase-coded LFM signal is generated. The center frequency, bandwidth, coding pattern, and bit rate of the generated signals can be flexibly adjusted. In the experiment, a phase-coded LFM microwave signal with a bandwidth of 5.0 GHz is generated, corresponding to a time bandwidth product (TBWP) of 2.8×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> . The center frequency and bandwidth of the generated signals are adjusted from 9.7 to 10.7 GHz and from 5.0 to 3.0 GHz, respectively. Meanwhile, different coding patterns and rates are also implemented, indicating that the phase-coded LFM signal can be used in wireless communications. The proposed approach can potentially be applied to multifunctional integration in radar.

On-Chip Photonic Generation of Tunable Wideband Phase-Coded Linearly-Chirped Microwave Waveforms

On-chip photonic generation of tunable wideband phase-coded linearly-chirped microwave waveforms (PC-LCMWs) is proposed and experimentally demonstrated. The on-chip generation system consists of two main parts. One part is a hybrid Fourier-domain mode-locked opto-electronic oscillator (FDML-OEO) for a wideband linearly-chirped microwave waveform (LCMW) generation; the other part is a high-speed microwave photonic phase shifter (MPPS) to perform the phase-coding. By synchronizing the two parts, a PC-LCMW is finally generated. In the proposed chip, a thermally-tunable ultrahigh-Q micro-ring resonator (MRR) is a key component which is incorporated in the FDML-OEO loop to select the oscillation frequency, and an electrically-tunable micro-disk resonator (MDR), as another key component, is used to code the phase of the generated microwave signal while maintaining the amplitude by controlling the free carrier concentration in the lateral PN junction of the disk. With the use of the two key component chips, an experiment is performed and different PC-LCMWs are generated with a tunable center frequency from 12 to 16 GHz, a bandwidth from 2 to 6 GHz, and phase code of 7-bit and 13-bit Barker code. In particular, a PC-LCMW with a maximum bandwidth as wide as 6 GHz and an ultra-large time-bandwidth product (TBWP) as large as 1.96×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> is experimentally demonstrated. The proposed integrated PC-LCMW generation system holds great advantages including ultracompact configuration and fast tunability, which holds a high potential for applications in modern high-resolution multi-functional radar system.

Polarization controlled dispersion tunable optoelectronic oscillator and frequency octupling without bandpass filter

Polarization controlled dispersion tunable optoelectronic oscillator and frequency octupling without bandpass filter

Finely Tunable Coupled Optoelectronic Oscillator Based on Injection Locking and Phase Locked Loop

Finely Tunable Coupled Optoelectronic Oscillator Based on Injection Locking and Phase Locked Loop

Study on the performance of injection-locked single-loop optoelectronic oscillators in presence of additive white Gaussian noise

Abstract This paper presents a detailed study on the synchronization characteristics of a single-loop optoelectronic oscillator (OEO) under the influence of radiofrequency (RF) signal, which is contaminated with additive white Gaussian noise (AWGN). The influence of the AWGN on the performance of the injection-locked optoelectronic oscillator (IL-OEO) is investigated in terms of the probability of losing lock, average beat frequency, and frequency of skipping cycles. Fokker–Planck technique is utilized to derive the expression for the probability density function (PDF) of the phase difference between the injection RF signal and the OEO output signal. The probability of losing lock on the two sides of the IL-OEO oscillation frequency and the frequency of skipping cycles are calculated in terms of the signal-to-noise ratio (SNR). An expression for the phase noise spectrum of the IL-OEO is also presented. The analytical model predicts the phase noise of the IL-OEO at very low offset frequencies with the accuracy rate of 75 %, in the presence of AWGN. Experimental verifications are carried out to prove the validity of the proposed analytical model.

Ultra-flat multicarrier light source based on recirculating frequency shift loop driven by a parity-time symmetric optoelectronic oscillator.

A multicarrier light source based on a recirculating frequency shift loop (RFSL) driven by a parity-time (PT)-symmetric optoelectronic oscillator (OEO) is proposed and experimentally demonstrated. The impact of the side-mode suppression ratio (SMSR) of the radio frequency (RF) signal on the multicarrier is studied for the first time, to our knowledge. The RFSL driven by PT-symmetric OEO significantly optimizes the phase noise and flatness of the multicarrier, facilitating the system miniaturization. In the experiment, a 10.019GHz RF signal with a SMSR of 42dB is generated with -98.63d B c/H z measured phase noise at 10kHz offset frequency (actual phase noise should be lower than -122.87d B c/H z). Up to 120 subcarriers with 2.32dB flatness are obtained successfully, covering the overall bandwidth of approximately 1.2THz.

High-Sensitivity Fiber-Optic Voltage Sensor Based on an Optoelectronic Oscillator Using a PZT-Stack and an Equivalent Phase-Shifted Fiber Bragg Grating

High-Sensitivity Fiber-Optic Voltage Sensor Based on an Optoelectronic Oscillator Using a PZT-Stack and an Equivalent Phase-Shifted Fiber Bragg Grating

Optical Tunable Frequency-Doubling OEO Using a Chirped FBG Based on Orthogonally Polarized Double Sideband Modulation

We propose and experimentally demonstrate a tunable frequency-doubling optoelectronic oscillator (FD-OEO) based on a single-bandpass dispersion-induced microwave photonic filter (MPF) consisting of a Mach–Zehnder modulator (MZM), a linearly chirped fiber Bragg grating and polarization-multiplexed dual-loop. Thanks to the polarization dependence of the MZM, a special double sideband modulation is implemented where the optical carrier (OC) and subcarriers are orthogonally polarized. By simply tuning the PC in the OEO loop, the phase difference between the orthogonal polarization carrier and two sidebands can be controlled, and thus the center frequency of the fundamental OEO can be tuned. Furthermore, a PC and a polarizer are placed outside the OEO to achieve optical carrier suppression (OCS) modulation, which ensures that a frequency-tunable microwave signal at the second-harmonic frequency is generated. In the experiment, a fundamental frequency signal with tunable frequency from 3.6 to 6.85 GHz and FD-OEO with a tunable frequency range from 7.2 to 13.7 GHz are generated.

Nonlinear dynamics of the dual-loop optoelectronic oscillator based on polarization multiplexing

This paper focuses on the temporal dynamics of the dual-loop optoelectronic oscillator (OEO) based on polarization multiplexing. The delay-differential equation (DDE) for the dual-loop OEO system is presented for the first time. After employing microwave envelope method to simplify the DDE, the envelope signal equation describing the system dynamics is obtained. Stability analysis of the static solution of the envelope signal equation is also performed, and the gain thresholds for the system to exhibit various dynamic behaviours are calculated. Moreover, the proposed nonlinear dynamics approach reveals the stability of microwave envelope in detail as a function of the feedback gain and coupling coefficient, which indicates that there is not monotonously incremental relationship between envelope amplitude of the ultrapure microwave and the feedback gain. Finally, the experimental measurements confirm the results obtained from the theoretical and numerical analysis.

Highly sensitive torsion sensor based on a coupled optoelectronic oscillator incorporating nonlinear polarization rotation.

We propose and demonstrate a new, to the best of our knowledge, technique to implement a high-speed and highly sensitive torsion sensor based on a coupled optoelectronic oscillator (COEO) incorporating nonlinear polarization rotation (NPR). The COEO consists of a mode-locked laser loop and an OEO loop. In the laser loop, the NPR effect effectively induces intensity- and wavelength-dependent loss, which acts as a Lyot birefringent fiber filter. When twisting the polarization-maintaining fiber (PMF), the transmission of the filter varies as well as the laser output wavelength. In the OEO loop, the optical source is provided by the output signal of the mode-locked laser. The variation in the optical carrier wavelength changes the time delay and the oscillation frequency of the OEO loop. The oscillation frequency shift is a linear function of the twist angle. Sensitivities of -60.006 Hz/deg over 360° for a 48 cm PMF and -180.996 Hz/deg over 92° for a 22 cm PMF are achieved.

Neuromorphic regenerative memory optoelectronic oscillator.

Neuromorphic spiking information processing based on neuron-like excitable effect has achieved rapid development in recent years due to its advantages such as ultra-high operation speed, programming-free implementation and low power consumption. However, the current physical platforms lack building blocks like compilers, logic gates, and more importantly, data memory. These factors become the shackles to construct a full-physical layer neural network. In this paper, a neuromorphic regenerative memory scheme is proposed based on a time-delayed broadband nonlinear optoelectronic oscillator (OEO), which enables reshaping and regenerating on-off keying encoding sequences. Through biasing the dual-drive Mach-Zehnder electro-optic modulator in the OEO cavity near its minimum transmission point, the OEO can work in excitable regime, where localized states are maintained for robust nonlinear spiking response. Both simulation and experiment are carried out to demonstrate the proposed scheme, where the simulation results and the experimental results fit in with each other. The proposed OEO-based neuromorphic regenerative memory scheme exhibits long-term response ability for short-term excitation, which shows an enormous application potential for high-speed neuromorphic information buffering, optoelectronic interconnection and computing.

Wideband frequency-tunable optoelectronic oscillator with ultra-narrow linewidth based on stimulated Brillouin scattering

We propose and theoretically analyze a wideband frequency-tunable optoelectronic oscillator based on stimulated Brillouin scattering (SBS) and gain–loss superposition with ultra-narrow linewidth. Typically, the linewidth of optoelectronic oscillator (OEO) based on SBS is difficult to narrow because of the relatively fixed 3-dB bandwidth of SBS. In the structure, three generated new pump lights with certain frequency intervals generated by optical modulation on the pump laser light are launched in a highly nonlinear fiber (HNLF) from the direction opposite to the phase modulated signals, where the SBS effect occurs. The gain spectrum of one pump light is superimposed with the loss spectra of the other two pump lights. As a result the linewidth of the output signal reduces highly compared with conventional OEOs based on SBS. Consequently, a microwave signal with wide tunable range of 1 GHz to 40 GHz and near 60% linewidth reduction at most is realized in theory. Particularly, the theoretical simulation of the phase noise is about −112.5 dBc/Hz at 10 kHz offset when the wavelength of the continuous wave laser is 1550 nm and the frequency of the output signal is 35 GHz. In addition, the proposed method can be generalized, theoretically, to any OEO based on SBS to effectively reduce its linewidth. Overall, the proposed structure improves the quality of generated signals prominently and has vast potential in microwave generation.

High-precision temperature-compensated fiber Bragg grating axial strain sensing system based on a dual-loop optoelectronic oscillator with the enhanced Vernier effect.

A temperature-compensated fiber Bragg grating (FBG) axial strain sensor based on a two-dual-loop optoelectronic oscillator (OEO) with the enhanced Vernier effect is proposed and experimentally demonstrated. The sensing head consists of two cascaded FBGs, one of which acts as a sensing FBG to measure both the axial strain and temperature and the other as a reference FBG to detect temperature. Acting as the optical carrier, the reflected optical signal of the sensing head is divided into two paths with opposite dispersion coefficients and slightly different lengths to achieve an enhanced Vernier effect. After being divided by a wavelength division multiplexer, the optical signal launches into two electrical paths with different electrical bandpass filters (EBPFs) for frequency division multiplexing. The EBPF I selects the microwave signal generated by the sensing FBG, while the EBPF II selects the microwave signal generated by the reference FBG. Therefore, the axial strain and temperature can be recovered by recording the microwave frequency within EBPF I, and the temperature can be interrogated by tracking the microwave frequency within EBPF II. The axial strain applied on the sensing FBG can be distinguished by solving the cross-sensitivity matrix. The results show that the sensitivity of the dual-loop OEO is much greater than that of the single-loop OEO. The maximum measurement error for the axial strain is 0.112µε, and the maximum temperature compensation error is as low as 0.024°C in the dual-loop OEO, which is far less than that in the single-loop OEO. The enhanced Vernier effect not only improves the sensitivity, but also reduces the temperature compensation error.

Theoretical investigation of physical parameters measurements of a liquid in a vessel using optoelectronic oscillators

Theoretical investigation of physical parameters measurements of a liquid in a vessel using optoelectronic oscillators