Frequency-doubling Optoelectronic Oscillator Research Articles

Frequency-Doubling Optoelectronic Oscillator with Fundamental Frequency Signal Cancellation

Frequency-Doubling Optoelectronic Oscillator with Fundamental Frequency Signal Cancellation

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.

Widely tunable frequency-doubling optoelectronic oscillator using a polarization modulator and a phase-shifted fiber Bragg grating

A frequency-doubling optoelectronic oscillator with wideband frequency tunability implemented using a polarization modulator (PolM) and a phase-shifted fiber Bragg grating (PS-FBG) is proposed and experimentally demonstrated. In the proposed structure, the output from the PolM is divided into two branches by an optical coupler. In the lower branch, an optoelectronic feedback loop is formed in which a tunable microwave photonic filter (MPF) is constructed by the joint operation of the PolM, the PS-FBG, a tunable laser source (TLS), a polarization controller (PC), and a polarizer, the MPF serves as an oscillation mode selector that its central frequency is a function of the frequency difference between the TLS and the notch of the PS-FBG. In the upper branch, an equivalent Mach–Zehnder modulator (MZM) is performed by the joint use of the PolM, a second PC, and a second polarizer, the second PC is adjusted to let the bias point of the MZM located at the minimum transmission point (MITP), which generates an optical signal with two sidebands at the ±first orders. By beating the two sidebands at a second photodetector (PD), a frequency-doubled microwave signal is generated. By simply adjusting the wavelength of the TLS, the central frequency of the MPF is shifted, and the fundamental oscillation and its frequency-doubled signals can be tuned. The detailed theoretical study is achieved, and a verified experiment is established. A fundamental oscillation signal with a frequency tuning range from 9.39 to 15.4 GHz is generated in the OEO loop, which is multiplied to generate a tunable frequency-doubled signal. Their overall performances are also investigated.

Multifold clock recovery and demultiplexing based on a polarization-dependent phase modulator incorporated frequency-doubling optoelectronic oscillator

A novel multifold clock recovery structure with demultiplexing function based on a frequency-doubling optoelectronic oscillator (FD-OEO) incorporating a common commercial phase modulator (PM) is proposed and experimentally demonstrated. A special phase modulation is obtained thanks to polarization-sensitive feature of LiNbO3 crystal of the PM. The special phase modulated signal is then split two parts connected by two pairs of polarization controllers (PCs) and polarizers to perform polarization interference and phase modulation to intensity modulation conversion. By controlling the PCs, the joint use of PC and polarizer in the loop is to guarantee an OEO with fundamental frequency self-oscillation, while the other outside of the OEO obtains frequency-doubled microwave signal at the output of the photodetector. Additionally, an optical filter can be inserted into the outside branch to only allow ±2nd-order sidebands pass through and realize frequency quadrupling after beating at the PD. Therefore, a prescaled clock at 10 GHz, a line-rate clock at 20 GHz and a 40 GHz frequency-doubled clock can be extracted from the injection-locked OEO respectively when a 2×10Gb∕s optical time division multiplexing (OTDM) data signal is injected. A twofold time division demultiplexing is demonstrated. Theoretical analysis is developed, which is validated by an experiment.

Wideband Tunable Frequency-Doubling Optoelectronic Oscillator Using a Polarization Modulator and an Optical Bandpass Filter**Supported by the National Natural Science Foundation of China under Grant No 61675196, the National Basic Research Program of China under Grant No 2014CB340102, the National High-Tech Research and Development Program of China under Grant No 2015AA016903, and the Open Research of Beijing University of Posts and

A wideband tunable frequency-doubling optoelectronic oscillator (FD-OEO) is proposed and experimentally demonstrated based on a polarization modulator and an optical bandpass filter (OBPF). The central frequency of the correspondingly fundamental OEO could be adjusted by tuning the bandwidth and central frequency of the OBPF, which could also be regarded as a photonic-assisted tunable microwave filter. The frequency tuning range of the FD-OEO covers from 9.5 to 32.8 GHz, and the single sideband phase noise of the fundamental signal is lower than −100 dBc/Hz at an offset of 10 kHz. Moreover, the frequency stability of the generated signal is investigated by measuring its Allan deviation. The Allan deviation of the generated fundamental signal at 10 GHz is 2.39×10−9.

Photonic Frequency Down-Converter based on a Frequency-Doubling OEO using Two Cascaded EAMs

A photonic frequency down-converter based on a frequency-doubling optoelectronic oscillator (OEO) using two cascaded electro-absorption modulators (EAMs) is proposed and experimentally demonstrated. The use of the two cascaded EAMs allows the OEO feedback loop used to generate the local oscillator (LO) signal and the down-conversion section to be structurally isolated, so that the proposed photonic frequency down-converter has high RF to LO isolation. The phase noise of the frequency-doubled 20-GHz LO signal and that of the down-converted 3-GHz IF signal were measured to be −97.80 and −95.32 dBc/Hz at an offset frequency of 10 kHz, respectively. The spurious free dynamic range measured using a two-tone test was 87.02 dB $\cdot $ Hz2/3. The bit error rate performance was also investigated with a 20-GHz RF signal modulated by 1.25 Gb/s data.

A compact frequency‐doubling opto‐electronic oscillator using cascaded electroabsorption modulators

ABSTRACTA compact frequency‐doubling optoelectronic oscillator (FD‐OEO) using two cascaded electro‐absorption modulators (EAMs) is proposed and experimentally demonstrated. The FD‐OEO is configured with two cascaded EAMs driven by signals having a 180° phase difference, so that the second EAM produces an output signal with a suppressed first‐order side band, thus generating a frequency doubled signal. The phase noise characteristics of the fundamental (10 GHz) and frequency‐doubled (20 GHz) signals are measured to be −94.25 dBc/Hz and −87.71 dBc/Hz, respectively, at a frequency offset of 10 kHz. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:526–529, 2016

Frequency-doubling optoelectronic oscillator based on destructive interference

A frequency-doubling optoelectronic oscillator (OEO) using two cascaded modulators based on destructive interference is proposed and experimentally demonstrated. In the proposed system, we utilize a cascaded modulator including a phase modulator and an intensity modulator, which implements a carrier-suppressed double-sideband modulation based on destructive interference to generate a frequency-doubled microwave signal. Meanwhile, the phase modulator is connected by a chirp fiber Bragg grating in the loop, which forms a microwave photonic filter to select the fundamental frequency signal in the OEO loop. As a result, a frequency-doubled microwave signal at 17.9 and 20.5 GHz is generated, respectively. The phase noises and the long-term stability of the generated microwave signals are also investigated.

Frequency-Doubling OEO Using the Polarization Property of LiNbO<sub>3</sub> Modulator

A frequency-doubling optoelectronic oscillator (OEO) has been proposed. In the proposed device, several passive components are introduced into the traditional OEO to handle the polarization state of the laser in the feedback loop. Making use of the polarization dependence of the LiNbO3 intensity modulator, a special double sidebands modulation is implemented where the polarization direction of the optical carrier is orthogonal with that of the first-order sidebands. Two polarizers are used to choose the specific optical components from the modulated light, which ensures that a microwave signal at the second-harmonic frequency outputs from the OEO when the fundamental frequency signal is self-oscillating in the loop. In the experiment, a 20-GHz frequency-doubled signal was generated, whose phase noise performance and immunity to the polarization drift were measured and evaluated.

A Widely and Continuously Tunable Frequency Doubling Optoelectronic Oscillator

We report a widely and continuously tunable frequency doubling optoelectronic oscillator (FD-OEO) based on a polarization modulator. The proposed approach is theoretically analyzed and experimentally verified. In a proof-of-concept experiment, the FD-OEO is continuously tuned from 8.8 to 37.6 GHz by adjusting the bandwidth of an optical bandpass filter inside the OEO loop. The phase noise performance of the generated microwave signals is also studied. The single sideband phase noise of the frequency doubled tone is below -103 dBc/Hz at an offset of 10 kHz.

Gaussian-like dual-wavelength prescaled clock recovery with simultaneous frequency-doubled clock recovery using an optoelectronic oscillator

A novel multifunctional frequency-doubling optoelectronic oscillator (FD-OEO) mainly based on a Mach-Zehnder modulator (MZM) cascaded with a phase modulator (PM) and a subsequent optical bandpass filter (OBPF) is proposed. We experimentally demonstrate simultaneous operations of frequency-doubled optical clock (FD-OC) recovery, low-duty-cycle dual-wavelength prescaled OC recovery and error-free fourfold time division demultiplexing with the proposed OEO injected with a 4 × 25-Gb/s optical time-division-multiplexing (OTDM) signal. We show that the proposed FD-OEO operates well for both the differential phase shift keying (DPSK) and on-off keying (OOK) modulation formats. The extracted dual-wavelength prescaled OC is proved to be nearly transform-limited with Gaussian-like shape. Furthermore, all four 25-Gb/s tributaries can be selectively demultiplexed by adjusting the phase shifters in the OEO loop. The power penalty at a bit error rate (BER) of 10(-9) is measured to be 2.4 dB, 1.2 dB for the best channel for DPSK signal and to be 2.5 dB, 1.1 dB for the best channel for OOK signal. In addition, as an extra benefit of the OEO, low-phase-noise prescaled electrical clock (EC) is also extracted.

Simultaneous prescaled and frequency-doubled clock recovery using an injection-locked optoelectronic oscillator

A frequency-doubling optoelectronic oscillator (FD-OEO) using tandem Mach–Zehnder modulators (MZMs) biased at the peak transmission point is proposed and experimentally demonstrated. Multifunctional operations of nearly chirp-free frequency-doubled optical clock (FD-OC) recovery, low-duty-cycle prescaled OC recovery and error-free fourfold demultiplexing of a 100-Gb/s optical time division multiplexing (OTDM) signal are achieved simultaneously with the proposed FD-OEO composed of low-frequency devices. As an intrinsic property, prescaled electrical clock (EC) with 167.15-fs root-mean-square (RMS) timing jitter is extracted.

一种倍频光电振荡器的实现方法

一种倍频光电振荡器的实现方法

A Frequency-Doubling Optoelectronic Oscillator using a Three-Arm Dual-Output Mach-Zehnder Modulator

This paper proposes a frequency-doubling optoelectronic oscillator employing a novel three-arm dual-output Mach-Zehnder modulator (MZM). One output of the MZM generates the fundamental-frequency signal which is recycled by the microwave optical fiber link for oscillation, and the other output can generate the frequency-doubled signal. Experiment was conducted using a commercial two-arm MZM, a phase modulator, and an optical fiber link of 89 meters in length. A 19-GHz frequency-doubled signal was successively obtained with fundamental signal suppression more than 36 dB.

Frequency-Doubling Optoelectronic Oscillator Using DSB-SC Modulation and Carrier Recovery Based on Stimulated Brillouin Scattering

A tunable frequency-doubling optoelectronic oscillator (OEO) is proposed and experimentally demonstrated, of which the novelty lies in the conjunction of the double-sideband suppressed carrier (DSB-SC) modulation and the carrier recovery based on stimulated Brillouin scattering (SBS) effect. Frequency-doubled signals are generated via the DSB-SC modulation, which is realized by using a polarization modulator (PolM) in combination with an optical polarizer. Then, the gain provided by the SBS effect is used to recover the suppressed optical carrier, such that a fundamental-frequency oscillating required in the OEO loop is maintained. In the experiment, frequency-doubled microwave signals at 6.1 and 20 GHz are generated and analyzed. Meanwhile, the stability of the generated signals is also investigated.

An electrically tunable frequency-doubling optoelectronic oscillator with operation based on stimulated Brillouin scattering

An electrically tunable frequency-doubling optoelectronic oscillator (OEO) with operation based on stimulated Brillouin scattering (SBS) and phase modulation is proposed and experimentally demonstrated. In this OEO configuration, the phase modulator in combination with an optical filter is employed to produce a frequency-doubling microwave signal, while the SBS effect provides the narrowband filtering and ensures the oscillation of the feedback driving signal at the fundamental frequency. By varying the Brillouin pump signal obtained from double-sideband–carrier-suppression modulation, the frequency tunability is realized. In our experiment, a continuous tunable frequency-doubling signal from 21.4 to 25 GHz is generated when the tuning signal applied to the intensity modulator is tuned from 200 MHz to 2 GHz.

High-Performance Photonic Microwave Downconverter Based on a Frequency-Doubling Optoelectronic Oscillator

Photonic microwave downconversion based on an optoelectronic oscillator (OEO) is interesting because the local oscillator signal is directly extracted from the RF signal, but some of the frequency components in the RF signal would leak to the oscillation signal due to the limited rejection ratio of the electrical bandpass filter in the OEO, which degrades the downconverted signal. In this paper, a high-performance photonic microwave downconverter based on a frequency-doubling OEO (FD-OEO) is proposed and demonstrated to avoid the direct degradation from the RF signal. A 20-GHz RF signal with 1-Gb/s data modulation is successfully downconverted by the FD-OEO. The phase noise at 10-kHz frequency offset of the extracted RF carrier by the FD-OEO is 14 dB lower than that extracted by a conventional OEO, and the receiver sensitivity of the downconverted signal has a 1.173-dB improvement. The downconverter needs only low-frequency devices, which may find application in phased-array antenna arrays, electronic warfare receivers, avionics, and wireless communication systems.

Optically Tunable Frequency-Doubling Brillouin Optoelectronic Oscillator With Carrier Phase-Shifted Double Sideband Modulation

An optically tunable frequency-doubling optoelectronic oscillator (FD-OEO) based on stimulated Brillouin scattering (SBS) and carrier phase-shifted double sideband (CPS-DSB) modulation is proposed and demonstrated. SBS effect provides narrowband filtering for the OEO to generate an oscillation signal with frequency equal to the Brillouin frequency shift, while a CPS-DSB modulation by using a dual-parallel Mach-Zehnder modulator is implemented to double the oscillation frequency. Owing to the wavelength-dependent Brillouin frequency shift, frequency tunability is realized by tuning the wavelength of the laser source. In the experiments, frequency-doubling microwave signals from 18.38 to 18.74 GHz are generated when the wavelength of the laser source is tuned from 1565 to 1535 nm.

Coupled frequency-doubling optoelectronic oscillator based on polarization modulation and polarization multiplexing

A coupled frequency-doubling optoelectronic oscillator (OEO) is proposed and experimentally demonstrated, which is constructed based on the perfect combination of polarization modulation and polarization multiplexing. A fundamental microwave signal at 9.95 GHz or a frequency-doubled microwave signal at 19.9 GHz is generated with a wavelength-independent sidemode-suppression ratio (SMSR) as high as 78 dB obtained. The phase noise of the generated 19.9-GHz signal is − 103.45 dBc/Hz at 10-kHz frequency offset, indicating a good short-term stability. The proposed scheme is simple and flexible, which can find applications in radars and wireless communications.

A Frequency-Doubling Optoelectronic Oscillator Based on a Dual-Parallel Mach–Zehnder Modulator and a Chirped Fiber Bragg Grating

A frequency-doubling optoelectronic oscillator (FD-OEO) based on a dual-parallel Mach-Zehnder modulator (DPMZM) and a chirped fiber Bragg grating (CFBG) has been demonstrated. The DPMZM implements a carrier phase-shifted double sideband (CPS-DSB) modulation to generate a microwave signal at the second-harmonic frequency, while the CFBG ensures the oscillation of the fundamental frequency signal by tailoring the phase relationships between the optical sidebands and the carrier. As a result, self-starting 10- and 20-GHz microwave signals with low phase noises are simultaneously generated.