4 research outputs found
Recommended from our members
Photonic Microwave Generation with Free-running Monolithic Optical Frequency Combs
Ultra-low phase noise microwaves are of great interest due to their applications in many fields such as Radar, Communication, GPS, Astronomy, etc. The conventional ultra-low noise microwave sources rely on the high-quality factor of microwave resonators such as sapphire-loaded cavities. On the other hand, high finesse optical cavities offer superior Q factors compared to microwave counterparts, thanks to the low loss and low dispersion in the optical domain. Recent advancements in optical frequency combs have made it possible to bring this stability into the microwave domain via phase-coherent optical frequency division. However, due to their complexity and size, these optical frequency division systems are confined primarily to laboratory environments. Mode-locked monolithic lasers (MMLL) offer ultra-low free-running intrinsic noise performance and are a viable alternative to conventional OFD systems. This ultra-low noise performance of the monolithic combs removes the phase/frequency stabilization requirement from OFD systems, reducing the size, weight, and power consumption of the system. This thesis describes the path towards realizing a simple free-running monolithic comb-based microwave oscillator in X-Band. The performance of this approach is comparable to best laboratory OFD systems but with significantly reduced size, weight, and power (SWaP)
Recommended from our members
X-Band photonic microwaves with phase noise below-180 dBc/Hz using a free-running monolithic comb
Free-running mode-locked monolithic optical frequency combs offer a compact and simple alternative to complicated optical frequency division schemes. Ultra-low free-running noise performance of these oscillators removes the necessity of external phase stabilization, making the microwave systems uncomplicated and compact with lower power consumption while liberating the sidebands of the carrier from servo bumps typically present around hundreds of kilohertz offsets. Here we present a free-running monolithic laser-based 8 GHz photonic microwaves generation and characterization with a cryogenically cooled power splitter to demonstrate a state-of-the-art phase noise floor of less than −180 dBc/Hz below 1 MHz offset from the carrier.
</p
Recommended from our members
Ultra-low phase noise microwave generation with a free-running monolithic femtosecond laser
Phase noise performance of photonic microwave systems, such as optical frequency division (OFD), can surpass state-of-the-art electronic oscillators by several orders of magnitude. However, high-finesse cavities and active stabilization requirements in OFD systems make them complicated and potentially unfit for field deployment. Ultra-low noise mode-locked monolithic lasers offer a viable alternative for a compact and simple photonic microwave system. Here we present a free-running monolithic laser-based 8 GHz microwave generation with ultra-low phase noise performance comparable to laboratory OFD systems. The measured noise performance reached −130 dBc/Hz at 100 Hz, – 150 dBc/Hz at 1 kHz, and –167 dBc/Hz at 10 kHz offsets from the 8-GHz carrier. We also report a sub-Poissonian noise floor of −179 dBc/Hz above 30 kHz (timing noise floor of 32 zs Hz−1/2), which is ∼12 dB below the noise floor of time-invariant shot noise. In addition to the low phase noise, the system is compact, with a power consumption of less than 9 W, and offers excellent potential for mobile or space-borne applications.</p