We report a dual-wave microwave comb signal generation system based on an active mode-locked optoelectronic oscillator (AML-OEO), with the output signal being a dual-center frequency microwave comb signal. We utilize an equivalent dual-band filter based on parallel filters, where both parallel filters are narrow-band filters. When the optoelectronic oscillator loop is running freely, the output signal is a single-frequency signal with a frequency equal to the bandwidth of one of the narrow-band filters in the equivalent dual-frequency filter. When an excitation signal with a frequency equal to the difference between the two filters is injected through the mixer, the oscillation mode of the loop changes and the output signal becomes a dual-frequency signal with a frequency equal to the center frequency of each of the two narrow-band filters. The mode intervals of the optoelectronic oscillator are calculated from the spectrogram, and after injecting an active mode-locked signal with the same frequency and mode interval size, it can be observed that multimode oscillations occur at two frequencies. Replacing different optical fibers to change the loop length and thus the mode interval, a dual-frequency microwave comb signal with a larger number of combs can be generated when an active mode-locked signal at the fundamental frequency is injected. The center frequency can be tuned by replacing the filter with a narrower center frequency and has a narrower bandwidth and lower price compared to commercial dual band filters.
We propose and demonstrate a self-reconfiguration network of high-precision time-frequency synchronization. The local oscillator (LO) signal and time reference signal generated by the central site are transmitted to the two-fiber unidirectional ring in opposite directions. The all-optical microwave phase conjugation and the time-frequency domain transform measurement are utilized to eliminate phase fluctuation and time delay introduced by optical fiber. The two-fiber unidirectional ring can automatically switch the working loop when the fiber link is broken and avoid manual intervention, which realizes the self-healing of the network. A 20 GHz frequency signal and 1 pulse per second time signal are transferred along a 7 km fiber ring. At 1000 s averaging time, the long-term frequency stability of the order of 10 to 16 and time stability of the order of ps can be achieved at remote sites. When the network is interrupted, the proposed system can automatically recover the time-frequency synchronization from the failure state within 37 ms.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.