The history, fabrication, theory, numerical modeling, optical properties, guidance mechanisms, and applications of photonic-crystal fibers are reviewed

Photonic-Crystal Fibers

I will overview our recent results on ultra-long lasers and will discuss the concept of a fiber laser with an open cavity that operates using random distributed feedback provided by Rayleigh scattering amplified through the Raman effect.

/pdf/random-distributed-feedback-fiber-laser-2tyd8nspi6.pdf

Random distributed feedback fiber laser

Raman amplification has enabled dramatic increases in the reach and capacity of lightwave systems. This tutorial explains why, starting with the fundamental properties of gain from stimulated Raman scattering. Next, noise accumulation from amplified spontaneous emission is reviewed, and the merits of distributing Raman gain along a transmission fiber are explained. Other sources of noise that are particularly relevant for Raman amplifiers are summarized. Finally, novel Raman pumping schemes that have recently been developed are highlighted.

https://www.osapublishing.org/viewmedia.cfm?URI=OFC-2003-TuC1&seq=0

Raman amplification for fiber communications systems

Apparatus and method for increasing the sensitivity in the detection of optical coherence tomography and low coherence interferometry (“LCI”) signals by detecting a parallel set of spectral bands, each band being a unique combination of optical frequencies. The LCI broad bandwidth source is split into N spectral bands. The N spectral bands are individually detected and processed to provide an increase in the signal-to-noise ratio by a factor of N. Each spectral band is detected by a separate photo detector and amplified. For each spectral band the signal is band pass filtered around the signal band by analog electronics and digitized, or, alternatively, the signal may be digitized and band pass filtered in software. As a consequence, the shot noise contribution to the signal is reduced by a factor equal to the number of spectral bands. The signal remains the same. The reduction of the shot noise increases the dynamic range and sensitivity of the system.

Apparatus and method for ranging and noise reduction of low coherence interferometry LCI and optical coherence tomography OCT signals by parallel detection of spectral bands

Random distributed feedback fibre lasers

We have discovered a new mechanism for passive Q switching of fiber lasers. 10-kW peak power pulses with ∼2-ns pulse widths are reported from a diode-pumped ytterbium-doped fiber laser. The laser generates a high-brightness Raman-dominated supercontinuum spectrum covering the complete window of transparency of silica fiber in the infrared from 1.06 to 2.3 µm

Supercontinuum self-Q-switched ytterbium fiber laser

A 39 dB-gain silica fibre Raman amplifier is demonstrated at 1.3 mu m using a 1064 nm pump. Cascaded Raman generation and amplification are achieved in a monolithic ring cavity constructed solely from conventional fibre components, i.e. fusion WDM couplers and standard silica fibre.

Y. Zhu

Papers

Supercontinuum self-Q-switched ytterbium fiber laser

High-gain, monolithic, cascaded fibre Raman amplifier operating at 1.3 mu m

High-gain monolithic cascaded Raman fiber amplifier operating at 1.3 µm

1.08‒2.2-µm supercontinuum generation from Yb 3+ -doped fiber laser