Antennas, quantum optics and near-field microscopy

Vahid Sandoghdar, Mario Agio, Xue-Wen Chen, Stephan Götzinger, Kwang-Geol Lee

The atom is the most elementary constituent of any model that describes the quantum nature of light–matter interaction. Because atoms emit and absorb light at well-defined frequencies, nineteenth century scientists thought of them as collections of harmonically oscillating electric dipole moments or EHDs. In the language of modern physics, the latter represent dipolar transitions among the various quantum mechanical states of an atom. In a strict definition, the field of quantum optics deals with problems that not only require the quantization of matter but also of the electromagnetic field, with examples such as (i) generation of squeezed light or Fock states, (ii) strong coupling of an atom and a photon, (iii) entanglement of a photon with an atom and (iv) Casimir and van der Waals forces. There are also many other important topics that have been discussed within the quantum optics community but do not necessarily require a full quantum electrodynamic (QED) treatment. Examples are (i) cooling and trapping of atoms, (ii) precision spectroscopy and (iii) modification of spontaneous emission. The simple picture of a TLS as an EHD remains very insightful and valuable to this day. Indeed, much of what we discuss in this chapter has to do with the interplay between the quantum and classical mechanical characters of dipolar oscillators. For instance, the extinction cross-section of a TLS, given by 3λ2/2π, can be derived just as well using quantum mechanics [70] or classical optics [234]. Another example, albeit more subtle, concerns the spontaneous emission rate.

Observation of acoustically induced modulation instability in a Brillouin photonic crystal fiber laser

Birgit Stiller, Thibaut Sylvestre

We report the experimental observation of self-induced modulation instability (MI) in a Brillouin fiber laser made with a solid-core photonic crystal fiber (PCF) with strong anomalous dispersion. We identify this MI as the result of parametric amplification of optical sidebands generated by guided acoustic modes within the core of the PCF. It is further shown that MI leads to passive harmonic mode locking and to the generation of a picosecond pulse train at a repetition rate of 1.15 GHz which matches the acoustic frequency of the fundamental acoustic mode of the PCF. (C) 2013 Optical Society of America

Experimental Observation of Discrete Solitons in a Temporal Photonic Lattice

Martin Wimmer, Alois Regensburger, Christoph Bersch, Mohammad-Ali Miri, Georgy Onishchukov, Demetrios N. Christodoulides, Ulf Peschel

We report the first experimental observation of solitons propagating in discrete steps through a temporal photonic lattice, which is implemented in a fiber-loop setup. Stable propagation over fifty coupling lengths is achieved.

Scalar and vector modulational instability induced by parametric resonance in periodically tapered PCFs

Andrea Armaroli, Maxime Droques, Arnaud Mussot, Alexandre Kudlinski, Fabio Biancalana

We analyze the modulational instability process induced by periodic variations of the parameters of a PCF along the propagation direction, induced by an analogue of the parametric resonance in mechanics. (C) 2013 Optical Society of America

Diffractive resonant radiation by spatial solitons in waveguide arrays

Truong X. Tran, Fabio Biancalana

Two techniques for temporal pulse compression in gas-filled hollow-core kagome photonic crystal fiber

K. F. Mak, J. C. Travers, N. Y. Joly, A. Abdolvand, P. St. J. Russell

We demonstrate temporal pulse compression in gas-filled kagome hollow-core photonic crystal fiber (PCF) using two different approaches: fiber-mirror compression based on self-phase modulation under normal dispersion, and soliton effect self-compression under anomalous dispersion with a decreasing pressure gradient. In the first, efficient compression to near-transform-limited pulses from 103 to 10.6 fs was achieved at output energies of 10.3 mu J. In the second, compression from 24 to 6.8 fs was achieved at output energies of 6.6 mu J, also with near-transform-limited pulse shapes. The results illustrate the potential of kagome-PCF for postprocessing the output of fiber lasers. We also show that, using a negative pressure gradient, ultrashort pulses can be delivered directly into vacuum. (C) 2013 Optical Society of America

Amplification of realistic Schrodinger-cat-state-like states by homodyne heralding

Amine Laghaout, Jonas S. Neergaard-Nielsen, Ioannes Rigas, Christian Kragh, Anders Tipsmark, Ulrik L. Andersen

We present a scheme for the amplification of Schrodinger cat states that collapses two smaller states onto their constructive interference via a homodyne projection. We analyze the performance of the amplification in terms of fidelity and success rate when the input consists of either exact coherent state superpositions or of photon-subtracted squeezed vacua. The impact of imprecise homodyne detection and of impure squeezing is quantified. We also assess the scalability of iterated amplifications. DOI: 10.1103/PhysRevA.87.043826

The photonic wheel - demonstration of a state of light with purely transverse angular momentum

P. Banzer, M. Neugebauer, A. Aiello, C. Marquardt, N. Lindlein, T. Bauer, G. Leuchs

In classical mechanics, a system may possess angular momentum which can be either transverse (e.g. in a spinning wheel) or longitudinal (e.g. for a spiraling seed falling from a tree) with respect to the direction of motion. However, for light, a typical massless wave system, the situation is less versatile. Photons are well-known to exhibit intrinsic angular momentum which is longitudinal only: the spin angular momentum defining the polarization and the orbital angular momentum associated with a spiraling phase front. Here we show that it is possible to generate a novel state of the light field that contains purely transverse angular momentum, the analogue of a spinning mechanical wheel. We realize this state by tight focusing of a polarization tailored light beam and measure it using an optical nano-probing technique. Such a novel state of the light field can find applications in optical tweezers and spanners where it allows for additional rotational degree of freedom not achievable in single-beam configurations so far.

A Simplified Implementation of the Bubble Analysis of Biopolymer Network Pores

Stefan Muenster, Ben Fabry

Nonlinear intermodal interactions in gas-filled hollow-core photonic crystal fibre

Francesco Tani, John C. Travers, Philip St. J. Russell

The emission of pressure-tunable ultra-violet dispersive waves into higher-order modes of a gas-filled kagome-PCF is experimentally and numerically demonstrated. Numerical evidence of a balance between Kerr-driven self-focusing and plasma-defocusing is also presented.