We propose and demonstrate a tunable optical filter based on a tapered silica microcylinder, whose diam- eter is gradually varied along its longitudinal axis. The tapered microcylinder comprises a slowly varying transition zone fabricated through the fiber drawing technique. Given the tapered diameter of the micro- cylinder, the resonant wavelengths can be tuned by displacing the tapered microcylinder. This tunable filter exhibits a high Q-factor （-106） and a large tuning range （〉1 free spectral range （FSR））.
We propose and demonstrate broadband Brillouin slow light using a multiple-longitudinal-mode tunable fiber laser as Brillouin pump. A tunable broadband Brillouin pump with a tuning range from 1 520 to 1 555 nm is generated using a fiber ring laser with a semiconductor optical amplifier （SOA） as its gain medium. The pump spectrum consists of a large number of longitudinal modes separated by 6 MHz. The 3-dB bandwidth is about 11.5 GHz, and its fluctuation is less than 100 MHz within the tuning range. An 8-Gb/s data signal can be delayed by up to 83.0 ps （bit error rate 〈 10^- 9） at 17-dBm pump power.
