Have you ever felt that the very title, Progress in Optics, conjured an image in your mind? Don’t you see a row of handsomely printed books, bearing the editorial stamp of one of the most brilliant members of the optics community, and chronicling the field of optics since the invention of the laser? If so, you are certain to move the bookend to make room for Volume 16, the latest of this series. It contains seven chapters on widely diverging topics, written by well-known authorities in their fields. These are: 1) Laser Selective Photophysics and Photochemistry by V. S. Letokhov, 2) Recent Advances in Phase Profiles (sic) Generation by J. J. Clair and C. I. Abitbol, 3 ) Computer-Generated Holograms: Techniques and Applications by W.-H. Lee, 4) Speckle Interferometry by A. E. Ennos, 5 ) Deformation  Invariant, Space-Variant Optical  Pattern Recognition by D. Casasent and D. Psaltis, 6) Light Emission from High-Current Surface-Spark Discharges by R. E. Beverly, and 7) Semiclassical Radiation  Theory within a  QuantumMechanical Framework by I. R. Senitzkt. The  breadth of topic  matter  spanned  by  these  chapters makes it impossible, for this reviewer at least, to pass judgement on the comprehensiveness, relevance, and completeness of every chapter. With an editorial board as prominent as that of Progress in Optics, however, it seems hardly likely that such comments should be necessary. It should certainly be possible to take the authority of each author as credible. The only remaining judgment to be  made on these chapters is their readability. In short, what are they like to read? The first sentence of the first chapter greets the eye with an obvious typographical error: “The creation of coherent laser light source, that have tunable radiation, opened the . . . .” Two pages later we find: “When two types of atoms or molecules of different isotopic composition ( A and B ) have even one spectral line that does not overlap with others, it is pos-

Progress in optics

Liquid-filled photonic crystal fibers and optofluidic devices require infiltration with a variety of liquids whose linear optical properties are still not well known over a broad spectral range, particularly in the near infrared. Hence, dispersion and absorption properties in the visible and near-infrared wavelength region have been determined for distilled water, heavy water, chloroform, carbon tetrachloride, toluene, ethanol, carbon disulfide, and nitrobenzene at a temperature of 20 °C. For the refractive index measurement a standard Abbe refractometer in combination with a white light laser and a technique to calculate correction terms to compensate for the dispersion of the glass prism has been used. New refractive index data and derived dispersion formulas between a wavelength of 500 nm and 1600 nm are presented in good agreement with sparsely existing reference data in this wavelength range. The absorption coefficient has been deduced from the difference of the losses of several identically prepared liquid filled glass cells or tubes of different lengths. We present absorption data in the wavelength region between 500 nm and 1750 nm.

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Linear refractive index and absorption measurements of nonlinear optical liquids in the visible and near-infrared spectral region

A topical review of numerical and experimental studies of supercontinuum generation in photonic crystal fiber is presented over the full range of experimentally reported parameters, from the femtosecond to the continuous-wave regime. Results from numerical simulations are used to discuss the temporal and spectral characteristics of the supercontinuum, and to interpret the physics of the underlying spectral broadening processes. Particular attention is given to the case of supercontinuum generation seeded by femtosecond pulses in the anomalous group velocity dispersion regime of photonic crystal fiber, where the processes of soliton fission, stimulated Raman scattering, and dispersive wave generation are reviewed in detail. The corresponding intensity and phase stability properties of the supercontinuum spectra generated under different conditions are also discussed.

Supercontinuum generation, photonic crystal fiber

The authors experimentally and theoretically demonstrate stimulated Brillouin scattering in a silicon nanowire supported by a pillar, which results from the tight confinement of both photons and phonons.

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Interaction between light and highly confined hypersound in a silicon photonic nanowire

Preface 1. Wave Theory of Optical Waveguides 2. Planar Optical Waveguides 3. Optical Fibers 4. Couple Mode Theory 5. Nonlinear Optical Effects in Optical Fibers 6. Finite Element Method 7. Beam Propagation Method 8. Staircase Concatention Method 9. Planar Lightwave Circuits 10. Theorems and Formulas Appendix

Fundamentals of optical waveguides

We have numerically studied a hollow-core photonic crystal fiber, with its core filled with highly nonlinear liquids such as carbon disulfide and nitrobenzene Calculations show that the fiber has an extremely high nonlinear parameter γ on the order of 24/W/m at 155 μm The group velocity dispersion of this fiber exhibits an anomalous region in the near-infrared, and its zero-dispersion wavelength is around 155 μm This leads to potentially significant improvements and a large bandwidth in supercontinuum generation The spectral properties of the supercontinuum generation in liquid-core photonic crystal fibers are simulated by solving the generalized nonlinear Schrodinger equation The results demonstrate that the liquid-core PCF is capable to generate dramatically broadened supercontinua in a range from 700 nm to more than 2500 nm when pumping at 155 μm with subpicosecond pulses

Theoretical design of a liquid-core photonic crystal fiber for supercontinuum generation.

We observe deterministic chaos in a simple network of electronic logic gates that are not regulated by a clocking signal The resulting power spectrum is ultra-wide-band, extending from dc to beyond 2 GHz The observed behavior is reproduced qualitatively using an autonomously updating Boolean model with signal propagation times that depend on the recent history of the gates and filtering of pulses of short duration, whose presence is confirmed experimentally Electronic Boolean chaos may find application as an ultra-wide-band source of radio waves

Boolean Chaos

Forward stimulated Brillouin scattering (FSBS) is observed in a standard 2-km-long highly nonlinear fiber. The frequency of FSBS arising from multiple radially guided acoustic resonances is observed up to gigahertz frequencies. The tight confinement of the light and acoustic field enhances the interaction and results in a large gain coefficient of 34.7 W−1 at a frequency of 933.8 MHz. We also find that the profile on the anti-Stokes side of the pump beam have lineshapes that are asymmetric, which we show is due to the interference between FSBS and the optical Kerr effect. The measured FSBS resonance linewidths are found to increase linearly with the acoustic frequency. Based on this scaling, we conclude that dominant contribution to the linewidth is from surface damping due to the fiber jacket and structural nonuniformities along the fiber.

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FSBS resonances observed in a standard highly nonlinear fiber

We undertake a systematic study of the dynamics of Boolean networks to determine the origin of chaos observed in recent experiments. Networks with nodes consisting of ideal logic gates are known to display either steady states, periodic behaviour or an ultraviolet catastrophe where the number of logic-transition events circulating in the network per unit time grows as a power law. In an experiment, the non-ideal behaviour of the logic gates prevents the ultraviolet catastrophe and may lead to deterministic chaos. We identify certain non-ideal features of real logic gates that enable chaos in experimental networks. We find that short-pulse rejection and asymmetry between the logic states tend to engender periodic behaviour, at least for the simplest networks. On the other hand, we find that a memory effect termed ‘degradation’ can generate chaos. Our results strongly suggest that deterministic chaos can be expected in a large class of experimental Boolean-like networks. Such devices may find application in a variety of technologies requiring fast complex waveforms or flat power spectra, and can be used as a test-bed for fundamental studies of real-world Boolean-like networks.

On the origin of chaos in autonomous Boolean networks.

We investigate the group velocity dispersion of tapered fibers that are immersed in different liquids. Using the Sellmeier equations fitted from measured refractive indices of these liquids, we are able to analyze the dispersion characteristics of the tapered fibers in a tailored liquid environment. Theoretical results show a large span of slowly varying anomalous group velocity dispersion characteristics. This leads to potentially significant improvements and a large bandwidth in supercontinuum generation in a tapered fiber. This holds true as well for a range of new fiber materials.

Rui Zhang

Papers

Theoretical design of a liquid-core photonic crystal fiber for supercontinuum generation.

Boolean Chaos

FSBS resonances observed in a standard highly nonlinear fiber

On the origin of chaos in autonomous Boolean networks.

Group velocity dispersion of tapered fibers immersed in different liquids