Optoelectronic Oscillator Research Articles

Abstract We present a theoretical and numerical study of nonlinear dynamics in an optoelectronic oscillator that follows Liénard-type behaviour. The sys-tem combines a resonant tunnelling diode−photodetector (RTD−PD) in series with a laser diode (LD), forming a solid-state system capable of generating ultrafast electrical oscillations while sim-ultaneously delivering coherent optical output. Our theoretical framework unifies the Liénard oscil-lator formalism with laser rate equations to describe the mutual interaction between the electrical and photonic subsystems. Our results reveal a rich variety of well-known dynamical regimes, including self-sustained and mixed-mode oscillations, frequency division, chaotic behavior confirmed through the computation of Lyapunov exponents and the 0-1 chaos test. To complement quantitative diag-nostics, we introduce a sound-based representation (sonification) of time-domain signals, providing an intuitive aid for identifying dynamical transitions. While our model is purely theoretical, simula-tion parameters are aligned with values reported in prior experimental studies of similar devices. The findings contribute to the understanding of nonlinear optoelectronic systems and may support the design of tunable components for future integrated photonic technologies.

A novel, to the best of our knowledge, optoelectronic oscillator (OEO) based on parity-time (PT) symmetry is proposed and experimentally demonstrated. In the proposed PT-symmetric OEO, a PT-symmetric structure with a phase modulator and an interleaved optical filter is incorporated to achieve the balance between the loop gain and loss in the OEO cavity, which significantly improves the side-mode suppression ratio (SMSR) of the generated microwave signals. In the experiment, a 10-GHz microwave signal has been successfully generated by the proposed PT-symmetric OEO, the side-mode suppression ratio of the RF output can reach 62.5 dB, and the phase noise can reach -148.88 dBc/Hz at 10-kHz offset via a 4.4-km OEO loop. Furthermore, the significant contrast between the generated 10-GHz signal's SMSR and phase noise is presented by using different fiber lengths. A YIG filter is incorporated into the OEO loop to verify the PT-symmetric effects at various oscillation frequencies. Experiment results indicate that the single-frequency oscillation can be tuned from 8 to 11 GHz with the SMSR beyond 50 dB and phase noise better than -130 dBc/Hz at 10 kHz offset via a 1-km OEO loop.

High-performance magnetic field and temperature dual-parameter sensor based on neural network assisted optoelectronic oscillator

Nowadays, optical sensors and their interrogation systems attract high attention from different research groups around the world. At the same time, a frequency interrogation method has already demonstrated its advantages in various applications. However, such method implementations based on an optoelectronic oscillator scheme needs simple and cost-effective frequency measurement methods. In this article we demonstrate an optoelectronic oscillator-based sensing scheme with a frequency downconversion scheme. As the optical sensor we utilized a phase-shifted waveguide Bragg grating for the liquid refractive index measurement. This grating is the notch filter in the optoelectronic oscillator feedback loop. The influence of external factors (in this case liquid refractive index change) leads to the grating resonant peak shift, which results in the optoelectronic oscillator output frequency shift. In turn, the frequency downconversion scheme reduces the output optoelectronic oscillator frequency value that allows to reduce sensing system’s complexity as well as the cost. For the optoelectronic oscillato numerical simulation, we used Ansys Lumerical software. In the simulation we change liquid refractive index from 1.39 to 1.391. In this case the optoelectronic oscillator output frequency changes in range from 3,01 to 12,89 GHz. The sensor interrogation frequency is 12,5 MHz. Also, we considered the frequency downconversion scheme implementation possibilities with commercially available devices. In conclusion it was found out, that our sensing system can be applied for the analysis of various liquids, including the detection and assessment of pathologies in blood and other biological fluids.

In this research, precision temperature sensing for electromagnetically harsh environments was achieved utilizing a low-threshold frequency-stable optoelectronic oscillator (OEO) leveraging stimulated Brillouin scattering (SBS). The sensing mechanism relied on the temperature-dependent frequency shift in the SBS-induced notch filter. By embedding this filter in the OEO feedback loop, the oscillator's output frequency was locked to the difference between the optical carrier frequency and the SBS notch center frequency. The temperature variations were translated into microwave frequency shifts through OEO oscillation, which was quantified with heterodyne detection. To suppress environmental perturbations, a Faraday rotation mirror (FRM) was integrated at the fiber end, creating a dual-pass SBS interaction that simultaneously enhanced the vibration immunity and reduced the SBS power threshold by 2.7 dB. The experimental results demonstrated a sensitivity of 1.0609 MHz/°C (R2 = 0.999) and a long-term stability of ±0.004 °C. This innovative scheme demonstrated significant advantages over conventional SBS-OEO temperature sensing approaches, particularly in terms of threshold reduction and environmental stability enhancement.

The mode-locking characteristic and microwave pulses regulation based on a self-mode-locking optoelectronic oscillator (SML-OEO) are analyzed and experimentally demonstrated. The oscillating modes in the SML-OEO cavity can be phase-coherent by means of the inherent oscillatory characterization via the opto-electronic loop. A self-excited microwave frequency comb (MFC) with the characteristics of a periodic rectangular pulse is generated. The phenomenon of nonlinear dynamical bifurcation in the SML-OEO, which leads to an amplification of the time scale in the system, where a single-cycle oscillatory pulse with a period of τ evolves into an oscillatory pulse with a period of 2τ. On this basis, by injecting a microwave signal with a period of 2τ/N (N is an integer) into the OEO loop, the gain in the OEO cavity is regulated so that the SML-OEO forms a new mode-locked state. The temporal domain characteristic forms a periodic rectangular pulse with a period of 2τ/N. The experiment results show that the microwave pulse of SML-OEO can be effectively regulated from 30 ns to 3.75 ns as N is set from 3 to 8.

Quadruple frequency-tunable and phase-tunable optoelectronic oscillator based on stimulated Brillouin scattering

Frequency domain approach to the steady state, stability, and phase noise analysis of externally injection-locked optoelectronic oscillators

Reconfigurable Mode-Locked Optoelectronic Oscillator Based on Intensity and Frequency Modulation of a Semiconductor Laser

Collinear acousto-optic diffraction based optoelectronic oscillator

The forthcoming sixth-generation and beyond wireless networks are poised to operate across an expansive frequency range-from microwave, millimetre wave to terahertz bands-to support ubiquitous connectivity in diverse application scenarios1-3. This necessitates a one-size-fits-all hardware solution that can be adaptively reconfigured within this wide spectrum to support full-band coverage and dynamic spectrum management4. However, existing electrical or photonic-assisted solutions face a lot of challenges in meeting this demand because of the limited bandwidths of the devices and the intrinsically rigid nature of system architectures5. Here we demonstrate adaptive wireless communications over an unprecedented frequency range spanning over 100 GHz, driven by a thin-film lithium niobate (TFLN) photonic wireless system. Leveraging the Pockels effect and scalability of the TFLN platform, we achieve monolithic integration of essential functional elements, including baseband modulation, broadband wireless-photonic conversion and reconfigurable carrier and local signal generation. Powered by broadband tunable optoelectronic oscillators, our signal sources operate across a record-wide frequency range from 0.5 GHz to 115 GHz with high-frequency stability and consistent coherence. Based on the broadband and reconfigurable integrated photonic solution, we realize full-link wireless communication across nine consecutive bands, achieving record lane speeds of up to 100 Gbps. The real-time reconfigurability further enables adaptive frequency allocation, a crucial ability to ensure enhanced reliability in complex spectrum environments. Our proposed system represents a marked step towards future full-spectrum and omni-scenario wireless networks.

Self-Mode-Locking Phenomenon and Microwave Signal Generation in Optoelectronic Oscillators

Polarization Reciprocal Angular Velocity Measurement Based on an Optoelectronic Oscillator

An approach to generating microwave pulse trains with independently-tunable pulse width and repetition rate is proposed and demonstrated based on an actively mode-locked optoelectronic oscillator (AML-OEO). In this scheme, an external amplitude-modulated signal, consisting of a carrier frequency and an envelope frequency, is injected into a dual-drive Mach-Zehnder modulator (DDMZM) acting as both the modulation device and the mode-locking device in the cavity. Active mode-locking is established by setting the envelope frequency of the amplitude-modulated signal identical to an integer time of the free spectral range (FSR) in the OEO. Microwave pulses are generated at the temporal positions where the amplitude-modulated signal has the maximum absolute amplitudes. In that regard, a higher carrier frequency equal to an integer multiple of the envelope frequency corresponds to a narrower pulse width. Hence, the pulse width and the repetition rate of the microwave pulse train obtained by AML-OEO can be independently tuned through setting the carrier frequency and the envelope frequency of the amplitude-modulated signal. Both numerical simulation and experiment have been accomplished to verify the feasibility of this method. Experimental results show that microwave pulse trains with a fixed repetition rate of 179.61 kHz and tunable pulse widths in the range of 365 ns to 105 ns are generated. In addition, microwave pulse trains with an identical pulse width of 165 ns and tunable repetition rates in the range of 179.61 kHz and 359.22 kHz are generated. Furthermore, an ultra-short microwave pulse train with a pulse width of 15.7 ns and a repetition rate of 475.468 kHz is obtained, where the pulse width is only 3.94% of that from an AML-OEO driven by a sinusoidal signal under an identical repetition rate. The proposed scheme provides a path to independently control the pulse width and the repetition rate of the microwave pulse train and obtain ultra-short microwave pulse trains in an AML-OEO.

A microwave frequency shift keying optoelectronic oscillator (FSK-OEO) based on an optical single-sideband (OSSB) modulator is proposed and experimentally demonstrated. In the proposed FSK-OEO, a dual-drive Mach-Zehnder modulator (DDMZM) is employed to implement the optical single sideband modulation through the 90° phase shift method. By appropriately setting the amplitude of the coding signal applied to the DC port of the DMZM, a FSK microwave signal is generated. In the experiment, 9.995/10.004 GHz and 10.371/11.014 GHz microwave FSK signals were successfully generated by using the proposed OEO scheme. This scheme can generate high-frequency and low-phase-noise FSK signals without relying on high-frequency signal sources. Additionally, the pulse compression performance of the generated signals was also demonstrated.

This paper presents a magnetic field responsivity-enhancement sensing system, which comprises a magnetic field enhanced-responsivity fiber Bragg grating (FBG) sensing unit and a microwave photonic demodulation system utilizing an optoelectronic oscillator (OEO). The enhanced-responsivity structure integrates a mechanical stress coupling mechanism and a magnetic field bias, applying both prestress and pre-magnetization to a giant magnetostrictive material to improve its magnetostrictive coefficient. The FBG is mechanically bonded to this structure, forming a highly responsive magnetic field sensing unit. The OEO-based demodulating system consists of a feedback oscillation loop incorporating a broadband light source, an optical modulator, a dispersion medium, and a photodetector. It converts the wavelength shift of the FBG induced by the magnetic field into a corresponding oscillation frequency shift of the OEO, enabling precise magnetic field measurement through frequency monitoring. Experimental results demonstrate that the magnetic field responsivity of the enhanced sensor reaches 3920Hz/mT, which is 16.3 times higher than that of the unenhanced configuration. A magnetic field resolution of 0.255µT and an accuracy of 51µT are achieved. The proposed magnetic field sensing system significantly enhances responsivity without increasing the complexity of the demodulation architecture. This work provides a novel, to our knowledge, and practical approach for high-accuracy magnetic field measurement in engineering applications.

A controllable frequency-hopping (FH) optoelectronic oscillator (OEO) based on active time-domain mode-locking (TDML) is proposed and experimentally demonstrated. In the proposed FH OEO, a dual-passband microwave photonic filter (MPF) based on phase-modulation-to-intensity-modulation (PM-IM) conversion is implemented using two laser diodes (LDs), a phase modulator, a micro-disk resonator, and a photodiode. Using two synchronized electrical control signals, the two LDs are intensity modulated to achieve the controllable two sub-passbands of the dual-passband MPF. Setting the frequencies of the two control signals equal to an integral multiple of the OEO free spectral range to achieve the TDML, a controllable FH signal generation scheme is achieved in the proposed FH OEO without the mode competition effect. In the experiment, a binary FH signal with controllable time duration, carrier frequency, and repetition period of the sub-signals is generated. The two sub-signals of the generated FH signal with an FH speed of about 21 ns, a time duration from 1% to 99% of 14.75 μs, a frequency range from 6 GHz to 18 GHz, and a repetition period from 14.75 μs to 147.5 ns are successfully demonstrated.

We demonstrate a dual-parameter control strategy that simultaneously modulates laser temperature and current to enhance the long-term frequency stability of optoelectronic oscillators (OEOs). A simulation environment was developed to model the frequency control dynamics, within which proportional-integral-derivative (PID) parameters were optimized using a genetic algorithm before hardware development. Experimental results show that the proposed approach expands the effective compensation range to 2.8 K without upgrading hardware, reduces frequency drift to 7.7×10-3 ppm/K, corresponding to the ppb/K level, and achieves an overlapping Allan deviation of 3.2×10-12 at 1000 s, while preserving phase noise performance. Strong agreement between simulated and experimental results (R2=0.998) confirms the effectiveness of the method for robust OEO stabilization.

Abstract An active mode-locking optoelectronic oscillator (AML-OEO) based on carrier recovery and single-sideband modulation is proposed and experimentally demonstrated. The single-sideband (SSB) modulation for the injection signal in upper branch and carrier-suppressed double-sideband (CS-DSB) modulation for the feedback signal in lower branch are combined to achieve the mode locking, and microwave frequency comb (MFC) signals with adjustable mode spacing can be generated. The experimental results show that the suppression ratio of the generated single-frequency signal is achieved up to 47 dB. In addition to the fundamental mode-locking signal, the 2nd-, 3rd-, 5th-, and 10th-order harmonic mode-locking signals are experimentally implemented by varying the frequency of the injection signal, and the maximum mode spacing is up to 4.49 MHz.

Generation of Dual-Frequency Microwave Pulse Based on Active Mode-Locked Optoelectronic Oscillator