Fig. 1. Schematic showings of the proposed optical length measurement technique based on a single-bandpass MPF. SLED, superluminescent LED; TOF, tunable optical filter; Pol, polarizer; PC, polarization controller; PBS, polarization beam splitter; PBC, polarization beam combiner; PolM, polarization modulator; DCF, dispersion compensation fiber; PD, photodetector; VNA, vector network analyzer.

Fig. 2. Basic implementation principle of the proposed MPF-based approach for measuring optical length change.

Fig. 3. Measured optical spectrum of the lightwave output from a SLED cascaded with a TOF.

Fig. 4. Measured frequency response of the MPF along with the change of optical length. (a) Center frequency is tuned ranging from 2 to 14 GHz. (b) Center frequency is tuned around 10 GHz.

Fig. 5. Relationship between the center frequency of the MPF and the optical length change.