Long-period fiber-grating-based gain equalizers.

Long-period fiber gratings are used to f latten the gain spectrum of erbium-doped fiber amplifiers. A broadband amplifier with <0.2-dB gain variation over 30 nm is presented. We also show that a chain of amplifiers can be equalized, leading to a bandwidth enhancement by a factor of 3.

Volume gratings for holographic storage applications written in high-quality germanosilicate glass.

Volume holographic gratings are written with ultraviolet light in high-optical-quality, commercially available Ge-doped silica films and in Ge-doped optical-fiber preform sections loaded with molecular hydrogen. In the film samples, peak refractive-index changes exceeding 10(-2) and a sensitivity (index change/absorbed energy density) of 0.4 × 10(-7) cm(3)/J are measured. Angular multiplexing of up to 51 gratings is demonstrated in the preform samples.

Birefringence reduction in side-written photoinduced fiber devices by a dual-exposure method.

An in situ birefringence measurement in conjunction with an atomic force microscope study shows that the geometric asymmetry of the side-writing process is a major cause of the induced birefringence in grating-based fiber devices. Measured refractive-index profiles of UV-exposed fibers clearly show the asymmetry in the induced index change. We demonstrate the use of a dual-exposure technique for producing low-birefringence devices.

All-optical data switching in an optical-fiber link using a GaAs optical bistable device.

We demonstrate the potential for all-optical processing of data transmitted over single-mode fibers using a bistable optical device (BOD). A stream of clock/bias pulses transmitted over a 1-km-long single-mode fiber (SMF) is processed by a pseudorandom data sequence of picosecond pulses transmitted over another 1-km SMF with the help of an optical bistable device. The processed signal from the BOD is transmitted over another kilometer of SMF and detected. The bistable device is an ~3-microm-thick molecular-beam epitaxially grown multiple-quantum-well structure of GaAs and GaAlAs. The clock pulses (at wavelength lambda = 870.0 nm) are just below the threshold for switching on the device, and the switching is accomplished by a pseudorandom data sequence of picosecond pulses (at lambda = 835.0 nm). The pulse width of the data transposed onto the clock stream by the BOD can be controlled by varying the phase of the switching data with respect to the clock, which may be of importance in interle aving data for time-division multiplexing. The experiment also demonstrates the potential of a BOD's capability of switching information from one wavelength to another. With optimized devices regeneration should be possible with reasonable gain.