All-Optical Arbitrary-Point Stable Quadruple Frequency Dissemination With Photonic Microwave Phase Conjugation

Abstract

We present an all-optical stable quadruple frequency dissemination for an arbitrary-access-point fiber-optic loop link using photonic microwave phase conjugation. A two-tone optical carrier is transferred as a round-trip probe signal to undergo the propagation delay of the entire fiber loop link. When the probe signal returns to the local site, a Mach-Zehnder modulator biased at the null point is used as a phase conjugator to reverse its phase, thus, implementing photonic microwave phase conjugation. At an arbitrary remote site, the phase-conjugated signal is photomixed with a tapped forward transferred signal to obtain a stable frequency-quadrupled radio frequency (RF) signal in which the fiber-induced phase drift is automatically eliminated. Owing to photonic microwave phase conjugation and photomixing, the local oscillator leakage and harmonics interference of electrical mixers employed in the previous compensation schemes can be avoided. We demonstrate the stable dissemination of a 20-GHz frequency-quadrupled RF signal to two arbitrary remote sites located at a 20-km fiber-optic loop link. The residual root-mean-square timing jitter in an hour is no more than 0.86 ps. The relative frequency stability of 10 −16 level at 1000 s averaging time can be realized at every remote site.

An All-Optical Ka-Band Microwave Long-Distance Dissemination System Based on an Optoelectronic Oscillator

“…The reference microwave signal is injected into the OEO loop to suppress side modes and stabilize the single-mode oscillation [14,15]. The OEO signal back to the local site is photomixed with the second harmonic of the reference signal to generate a phase-conjugated signal [16]. At the remote end, the backward phase-conjugated signal is photomixed with the probe signal to obtain a quadruple frequency signal, of which the phase is stabilized.…”

Phase-Stabilized Side-Branch RoF Link for Extensible Frequency Dissemination in Distributed Systems

“…As the number of remote stations sharply increasing in applications (e.g. in the squared kilometer arrays), different one-to-multipoint time and frequency delivery schemes have been proposed-the extensibility of synchronization system has been taken into consideration [23][24][25][26][27][28]. Unlike the GNSS-based synchronization, which is inherently capable of broadcasting time and frequency to multiple users, it is much harder for the ground-based sync system like optical fiber links to disseminate frequency to multiple locations.…”

“…Unlike the GNSS-based synchronization, which is inherently capable of broadcasting time and frequency to multiple users, it is much harder for the ground-based sync system like optical fiber links to disseminate frequency to multiple locations. In principle, the one-to-multipoint fiber-based sync schemes employ either a bus topology [23][24][25] or a ring-form topology [26][27][28] bus-topology and ring-form one-to-multipoint solutions, it has been realized by researchers that constructing a frequency dissemination network with branch topology may have unique advantage. Figure 1 illustrates this side-branch synchronization concept.…”

Multi-Access RF Frequency Dissemination Based on Round-Trip Three-Wavelength Optical Compensation Technique Over Fiber-Optic Link

“…Many teams have proposed a variety of networking RF frequency dissemination scheme [10]- [15]. L. Q. Yu et al, for example, proposed and demonstrated a networking scheme for a tree topology of 1 GHz RF frequency signal, and discussed the network capacity based on wavelength division multiplexing technology [12].…”