There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

1. Introduction 2. Theoretical foundations 3. Propagation and focusing of optical fields 4. Spatial resolution and position accuracy 5. Nanoscale optical microscopy 6. Near-field optical probes 7. Probe-sample distance control 8. Light emission and optical interaction in nanoscale environments 9. Quantum emitters 10. Dipole emission near planar interfaces 11. Photonic crystals and resonators 12. Surface plasmons 13. Forces in confined fields 14. Fluctuation-induced phenomena 15. Theoretical methods in nano-optics Appendices Index.

/pdf/principles-of-nano-optics-1hz998yqo8.pdf

Principles of nano-optics

Topological photonics is a rapidly emerging field of research in which geometrical and topological ideas are exploited to design and control the behavior of light. Drawing inspiration from the discovery of the quantum Hall effects and topological insulators in condensed matter, recent advances have shown how to engineer analogous effects also for photons, leading to remarkable phenomena such as the robust unidirectional propagation of light, which hold great promise for applications. Thanks to the flexibility and diversity of photonics systems, this field is also opening up new opportunities to realize exotic topological models and to probe and exploit topological effects in new ways. This article reviews experimental and theoretical developments in topological photonics across a wide range of experimental platforms, including photonic crystals, waveguides, metamaterials, cavities, optomechanics, silicon photonics, and circuit QED. A discussion of how changing the dimensionality and symmetries of photonics systems has allowed for the realization of different topological phases is offered, and progress in understanding the interplay of topology with non-Hermitian effects, such as dissipation, is reviewed. As an exciting perspective, topological photonics can be combined with optical nonlinearities, leading toward new collective phenomena and novel strongly correlated states of light, such as an analog of the fractional quantum Hall effect.

Topological Photonics

Microcavity physics and design will be reviewed. Following an overview of applications in quantum optics, communications and biosensing, recent advances in ultra-high-Q research will be presented.

Optical microcavities

The term photonic crystals appears because of the analogy between electron waves in crystals and the light waves in artificial periodic dielectric structures. During the recent years the investigation of one-, two-and three-dimensional periodic structures has attracted a widespread attention of the world optics community because of great potentiality of such structures in advanced applied optical fields. The interest in periodic structures has been stimulated by the fast development of semiconductor technology that now allows the fabrication of artificial structures, whose period is comparable with the wavelength of light in the visible and infrared ranges.

http://ieeexplore.ieee.org/iel5/6354/16969/00781867.pdf

Photonic crystals

A linear cavity design to produce a traveling wave operation as in a ring laser without the ring cavity design. All fiber configurations may be used to implement fiber lasers based on the linear cavity design.

Traveling-wave lasers with a linear cavity

With the maturation of crystal growth along with the nanofabrication of semiconductors there has been strong interest in creating optical microcavities for spontaneous emission control. The Vertical Cavity Surface Emitting Laser (VCSEL) was the first device to shrink the optical mode to sizes on the order of the wavelength of light[l].

Two-dimensional photonic crystal defect laser

A photochromic all-optical switch in telecommunication-grade fiber is fabricated by filling a fiber Bragg grating Fabry-Perot resonator with a spiro-oxazine solution. The narrow linewidth of the resonator allows for a high sensitivity of the resonance wavelengths to the index change. The switch is controlled by low intensity UV light exposure, and operation at infrared telecommunication wavelengths is demonstrated. The switching speed on the order of minutes has been achieved.

/pdf/spiro-oxazine-photochromic-fiber-optical-switch-2llfep4vrz.pdf

Spiro-oxazine photochromic fiber optical switch

For the first time, we experimentally demonstrate ultra-low-loss guiding in bi-periodic photonic crystal waveguides over a large bandwidth of more than 60 nm. In such bi-periodic waveguides, we achieve a propagation loss very similar to that of a dielectric ridge waveguide, which indicates that the dominant loss mechanism in these bi-periodic waveguides is due to fabrication imperfections.

Large-bandwidth ultra-low-loss guiding in bi-periodic photonic crystal waveguides

We present a new method for the calculation of the dispersion diagrams of general nonuniform waveguides. The method is based on the spatial Fourier transform (SFT) of the electromagnetic field distribution along the guiding direction. We demonstrate the validity and robustness of the SFT technique using several test cases. As an application, we apply the method to analyze the dispersion of biperiodic photonic crystal waveguides and show that the guiding bandwidths of these waveguides can be significantly enhanced by a proper choice of the two distinctive spatial periods of the biperiodic waveguides.

Reginald K. Lee

Papers

Traveling-wave lasers with a linear cavity

Two-dimensional photonic crystal defect laser

Spiro-oxazine photochromic fiber optical switch

Large-bandwidth ultra-low-loss guiding in bi-periodic photonic crystal waveguides

A new method for the calculation of the dispersion of nonperiodic photonic crystal waveguides