A Model for Designing Ultralow Noise Single- and Dual-Loop 10-GHz Optoelectronic Oscillators

20 GHz self‐oscillating parametric optical frequency comb generator using an electroabsorption modulated laser based dual‐loop optoelectronic oscillator

“…However, it produces a small mode spacing and takes the phase noise spurs forward. Here, the 2 km fibre length selection for the long loop is a trade‐off between low phase noise and a larger mode spacing [24]. For a dual‐loop OEO, when a stable oscillation is formed, there exist only common modes of the two loops.…”

Self-Oscillating Parametric Optical Frequency Comb Generation Using an Electroabsorption Modulated Laser-Based Optoelectronic Oscillator

“…So, a 10-GHz RF signal is produced, and it is feedback to drive the EML and the PM. In the loop, the length of SMF1 is 1km for a trade-off: a longer fiber would take the phase noise spurs forward with no significant improvement for the lower frequency part of SSB phase noise spectrum [20]. In the parametric mixer, 60% of the output signal from EDFA1 is launched into SMF2 with a length of 100 m, and then amplified with EDFA2 (Amonics) to act as parametric pumps.…”

“…phase noise is dominated by the EML frequency noise and the flicker noise from PD and electrical amplifiers [21]. Meanwhile, the laser frequency noise is converted to phase noise due to dispersion in SMF1 [20], which results in fluctuations in the low offset frequency range. It can also be found that there are several spurs at offset frequencies of multiple 200 kHz corresponding to the FSR of the OEO.…”

“…The SSB phase noise at 10 kHz offset is −109.89 dBc/Hz. This performance can be further improved by using low noise electrical amplifiers or a dual-loop configuration [20], [21].…”

On the stability & phase locking to a system reference of an optoelectronic oscillator with large delay

“…With the increase in correlation to 1000, the phase noise of the OEO improved to -145 dBc/Hz @ 10 kHz offset, however the measurement time thereby becomes prolonged. The spurs at 1 MHz and harmonics are caused by the laser frequency dither is applied to mitigate phase noise due to double Rayleigh scattering (DRS) [19]. The phase locked spectrum also shows that the bandwidth of the active loop filter needs to be reduced further to align the locked OEO with the free run OEO outside the loop filter bandwidth.…”