Yufei Bao

Tunable erbium-doped fiber ring laser precisely locked to the 50-GHz ITU frequency grid

A discretely tunable, single-frequency erbium-doped fiber ring laser demonstrates frequency locking to the 50-GHz ITU frequency grid with an accuracy of /spl plusmn/0.3 GHz and stability of /spl plusmn/0.05 GHz over a 50-nm tuning range. An output power of 7 mW and an extinction ratio of 45 dB make this single-frequency laser useful for a variety of DWDM applications.

High-speed liquid crystal fiber Fabry-Perot tunable filter

We report a liquid-crystal fiber Fabry-Perot tunable filter (LC-FFP-TF) with fast tuning (<33 /spl mu/s) over a 0.4-12 nm wavelength range centered at 1550 nm, at a temperature of 35/spl deg/C, using a commercially available electroclinic LC material, BDH764E. Typically, the fall time of the LC-FFP-TF is over an order of magnitude shorter than the rise time. For the first time to our knowledge, switching between two discrete wavelengths was demonstrated using an LC-FFP-TF.

FIBER FABRY-PEROT INTERFEROMETERS WITH VERY LOW POLARIZATION SENSITIVITY

The sensitivity to input polarization in long-cavity (1 cm to 5 m) and high-finesse (~ 100) fiber Fabry-Perot interferometers (FFPIs) is reduced from greater than 20 dB to between 0.2 and 0.6 dB in passband amplitude variation by the use of very-low-birefringence fibers. Furthermore the scanning FFPIs could allow very-high-resolution measurement of polarization-mode dispersion in short-length low-birefringence fibers.

POLARIZATION-MAINTAINING FIBER FABRY-PEROT TUNABLE FILTERS

We report what are to our knowledge the first high-performance polarization-maintaining single-mode fiber Fabry-Perot tunable filters. These filters simultaneously exhibited a loss of <2.5 dB, a finesse between 150 and 310, and an extinction ratio of >30 dB. A unique fabrication technique is developed that utilizes the tunability and the polarization resonance splitting inside the filter to align the birefringent axes at a pigtail-cavity joint. A general criterion is established for aligning polarization-maintaining fibers with elliptical inputs.

Use of a fiber Fabry-Perot tunable filter for high-speed optical packet switching: towards an experimental prototype

Merging optical technology with fast packet switching will develop generation-after-next advanced technologies scalable to a Tbit/second. Serious challenge of such an implementation is the lack of an optical switch that would have a fast tuning speed, wide tuning range, low insertion loss, and be highly selective with a narrow passband at the same time. For this purpose we propose using a recent experimental Los Alamos National Laboratory and Micron Optics Co. break through--building an optical switch that works three orders of magnitude faster than its commercial predecessors, has a wide tuning range and low insertion loss, and is highly selective. Fast optical tuning in several microseconds is necessary to perform high-speed optical packet switching. One approach to achieve fast wavelength tuning is to use high-speed piezoelectrically- driven Fiber Fabry-Perot tunable filters. A special controller has substantially improved the shape of the driving signal and the response of the filter. The fastest switching time achieved without ringing is 3.0 microseconds. At the same time, implementation of high-speed optical packet switching rises the challenge of the bit synchronization of the packets. Conventional circuits are inadequate when a fast clock recovery for the short length packets is required because they need thousands bits to lock on. To deal with it, we propose to implement a bit clock synchronization technique for high-sped packet-switched optical network on a packet-per-packet basis. As a result, a new packet-switched media access control protocol can be designed to minimize the searching time.