Relative stability of dither OPLL

In this paper, we analyze the relative stability of dither OPLL (optical phase-lock loop) in terms of phase margin (PM) considering loop delay into account. PM of modified first-order and second-order dither OPLL are calculated as a function of loop delay, damping factor and other parameters of the loop. A comparison between the stability of modified first-order and second-order dither OPLL is made, revealing that the second-order dither OPLL offers better stability. The effects of loop delay on the phase error variance (PEV) of the loop are shown.