G.A. Nowak

Low-power high-efficiency wavelength conversion based on modulational instability in high-nonlinearity fiber

Bandwidth and peak efficiency are enhanced for wavelength conversion based on induced modulation instability by use of dispersion-shifted fiber in which the nonlinearity (n(2)/A(eff)) is enhanced by a factor of ~4.5 over that of conventional dispersion-shifted fiber. We experimentally obtain a peak conversion efficiency as high as 28 dB over a 40-nm bandwidth with 600 mW of peak pump power. Considerations for further enhancement of fiber-based wavelength conversion are also discussed.

Low energy, enhanced supercontinuum generation in high nonlinearity dispersion-shifted fibers

Summary form only given. We generate >420 nm of supercontinuum (SC) by propagating pulses with energies <100 pJ through less than 2 m of dispersion-shifted fiber (DSF) in which the nonlinearity is enhanced by a factor of 4.5X over conventional DSF. By using high nonlinearity (Hi-NL) fiber, we reduce required pulse energies by 56% while simultaneously increasing the bandwidth by 86 nm compared with SC generated in conventional DSF of the same length and dispersion. We study the SC evolution as a function of pulse energy, fiber length and nonlinearity to find optimal conditions for maximum broadening without spectral distortion. Fiber-based SC has been demonstrated as a promising candidate for TDM/WDM sources and is generated typically in several kilometers of dispersion-tailored fiber. By generating the SC in a fiber shorter by three orders of magnitude, we obtain very stable pulses from the continuum and are able to accurately model the SC generation process. The short fiber length, however, requires high average power sources at OC-192 repetition rates. We reduce the average power required from a 10 Gb/s or OC-192 source to <550 mW by using 2 m of Hi-NL fiber.

Broader and flatter supercontinuum spectra in dispersion-tailored fibers

In summary, we find experimentally that dispersion decreasing (DD) fiber produces broader and smoother supercontinuum (SC) spectra than dispersion increasing (DI) or constant dispersion fiber. At 24.3 W peak input power, the SC spectrum of DD fiber is over 100 nm wide, over twice that created by constant dispersion fiber. The spectrum is also relatively flat over the 20-nm range from 1545-1565 nm. We will also report applications of the multiwavelength SC source to erbium doped fiber amplifiers and wavelength-division multiplexed fiber characterization.

Path average measurements of optical fiber nonlinearity using solitons

This paper experimentally demonstrates a new method to determine the optical nonlinearity of single-mode optical fiber. The technique takes advantage of the well-known nonlinear response of optical fibers and well-developed models for soliton pulse propagation to extract information about the fiber characteristics. Fiber nonlinearity can degrade the performance of communication systems by, for example, causing crosstalk and signal distortions. Measuring the fiber nonlinearity would greatly aid system designers in building and upgrading communication systems. The method is utilized to determine values for n/sub 2//A/sub eff/, where n/sub 2/ is the nonlinearity of the glass and A/sub eff/ is effective area of the core. On various lengths of Corning SMF-28 fiber and Corning SMF-DS fiber. Experimentally measured propagation results for short (/spl ap/2 ps) optical pulses are compared to computer simulated models to determine the fiber nonlinearity. The method finds n/sub 2//A/sub eff/=3.0/spl times/10/sup -10/ W/sup -1/ values for short lengths (/spl ap/400 m) of Corning SMF-28 fiber and values of 2.7/spl times/10/sup -10/ W/sup -1/ for longer lengths (/spl ap/6.5 km and /spl ap/20 km). The difference is expected due to the 8/9 polarization scrambling factor, and the values are in agreement with reported literature [1]. The method also determines n/sub 2//A/sub eff/=5.6/spl times/10/sup -10/ W/sup -1/ for a /spl ap/12 km Corning dispersion shifted fiber. The method has two major regimes of operation based on the soliton period, a characteristic length for solitons. For few soliton periods (Z/Z/sub 0/ /spl sim/4) the output pulsewidth is measured as a function of launched power. The methods major advantage is its capability to measure long lengths of standard fiber, where it uses only standard diagnostic tools such as autocorrelation and optical power measurements. However, the method is only applicable in the soliton regime of fibers.

Low-power, high-efficiency wavelength conversion based on modulation instability in high nonlinearity optical fiber

Summary form only given. We have demonstrated wavelength conversion over 40 nm with a peak efficiency of 28 dB at 600-mW pump power by employing induced modulation instability in dispersion-shifted fiber with a 5 X enhancement of nonlinearity. The results are consistent with theory and show -20 dB improvement in conversion efficiency of Michelson interferometric based wavelength conversion over semiconductor-based converters.

Self-synchronization of 100-Gbit/s TDM packets using a semiconductor laser amplifier and an intensity discriminator

Using a semiconductor laser amplifier followed by an intensity discriminator, we demonstrate packet clock extraction from a 100-Gbit/s eight-bit packet where the first pulse is 20 dB higher than the remaining bits. This extracted pulse can be used to process high-speed packets with low timing jitter within each packet frame. Previous demonstrations of self-synchronization have involved marker pulses at different wavelengths, polarization, intensity, or bit period. Our scheme allows all pulses in the packet to be identical, which simplifies packet generation and propagation in high-speed TDM systems.

Raman-pumped, dense dispersion-managed soliton transmission of 80 Gb/s OTDM data

The effects of radiation from dense dispersion-managed solitons into the normal-dispersion portion of their optical spectrum are observed for the first time in a novel Raman-pumped data transmission system. Filtering allows error-free propagation of 80-Gb/s OTDM data over 963 km.