An ultracompact OSNR monitor based on an integrated silicon microdisk resonator

Optical signal-to-noise ratio (OSNR) monitoring is essential for control and management of dynamic optical networks. Small footprint, low cost, and less power consumption are always desirable for such monitoring system. In this paper, we demonstrate an integrated dispersion-insensitive in-band OSNR monitor based on a compact silicon microdisk resonator (MDR) with only 5- μ m radius. The MDR (Q ∼ 54000) functions as an ultranarrow bandpass filter in the measurement of the OSNR. The monitoring performance is evaluated in a 10-Gb/s return-to-zero differential phase-shift keying (RZ-DPSK) system and is shown to be insensitive to chromatic dispersion from 0 to 850 ps/nm. The input power requirement of the monitor is also studied, which is consistent with the desire for low-power operation. Finally, we analyze the sensitivity of this technique for various Q factors of the MDRs. The results indicate that the sensitivity of this scheme can be improved with higher Q factors.