Narrow-band tunable optical filters based on cascaded Fabry-Perot cavities

Narrow-band tunable optical filters (TOF) based on three cascaded Fabry-Perot (FP) cavities are demonstrated. The FP cavities are fabricated with Pb(Mg1/3Nb2/3)O-3-PbTiO3 (PMN-PT), which is a transparent electro-optic ceramic. With a reflective design, the optical signal passes the three FP cavities twice. Thus we can design the FP cavities with a relatively low reflectivity, which enables it more tolerant to the loss in the cavities. Two types of TOF samples are fabricated. The specifications of the transmissive type TOF with dual-ports are tuning range >48nm, FWHM (full width half maximum) <0.06nm, insertion loss <3.87dB, crosstalk <-39dB, which meet the requirements by optical pertbrmance monitor (OPM) applications. The specifications of the reflective type TOF with single-port are tuning range >48nm, FWHM (full width half maximum) <0.1nm, insertion loss <2.82dB, crosstalk <-30dB, which can be employed in tunable fiber lasers for wavelength selection and tuning. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

Automated summary

This article demonstrates narrow-band tunable optical filters based on three cascaded Fabry-Perot cavities. The cavities are made of a transparent electro-optic ceramic material. By utilizing a reflective design, the optical signal passes through the three cavities twice, allowing for a more tolerant structure to loss. Two types of tunable optical filters are fabricated for different applications.