Supercontinuum

About: Supercontinuum is a research topic. Over the lifetime, 7071 publications have been published within this topic receiving 127671 citations.

Infiltrated Photonic Crystal Fibers for Sensing Applications.

Abstract: Photonic crystal fibers (PCFs) are a special class of optical fibers with a periodic arrangement of microstructured holes located in the fiber's cladding. Light confinement is achieved by means of either index-guiding, or the photonic bandgap effect in a low-index core. Ever since PCFs were first demonstrated in 1995, their special characteristics, such as potentially high birefringence, very small or high nonlinearity, low propagation losses, and controllable dispersion parameters, have rendered them unique for many applications, such as sensors, high-power pulse transmission, and biomedical studies. When the holes of PCFs are filled with solids, liquids or gases, unprecedented opportunities for applications emerge. These include, but are not limited in, supercontinuum generation, propulsion of atoms through a hollow fiber core, fiber-loaded Bose⁻Einstein condensates, as well as enhanced sensing and measurement devices. For this reason, infiltrated PCF have been the focus of intensive research in recent years. In this review, the fundamentals and fabrication of PCF infiltrated with different materials are discussed. In addition, potential applications of infiltrated PCF sensors are reviewed, identifying the challenges and limitations to scale up and commercialize this novel technology.

High repetition rate mid-infrared supercontinuum generation from 13 to 53 μm in robust step-index tellurite fibers

Abstract: We demonstrate broadband supercontinuum generation over two infrared octaves, spanning from 1.3 to 5.3 μm, with an output power of 150 mW in robust step-index tellurite fibers with core diameters between 3.5 and 4.3 μm. As a pump source, we use femtosecond mid-IR pulses from a home-built post-amplified optical parametric oscillator tunable between 1.5 and 4.0 μm at a 43 MHz repetition rate. We study the influence of core size, pump wavelength, and fiber length to optimize the spectral bandwidth. A key requirement for efficient spectral broadening is a low and rather flat average anomalous dispersion over a wide spectral range that can be tailored accordingly by changing the fiber core diameter. Numerical simulations based on the generalized nonlinear Schrodinger equation are in good agreement with experimental results.

Ultrabroadband Optical Phenomena in Quadratic Nonlinear Media

Abstract: We present a comprehensive framework to study the nonlinear evolution of ultrabroadband optical pulses in quadratic nonlinear media. We employ a nonlinear envelope equation that goes beyond the traditional slowly varying approximation and allows treatment of all the harmonics by means of a single equation. We exploit this model to simulate recently observed supercontinuum phenomena such as ultrabroadband parametric downconversion and the generation of octave-spanning spectra from femtosecond pulses.

Fourier transform spectrometry with a near-infrared supercontinuum source.

Abstract: Optical fiber based supercontinuum light sources combine the brightness of lasers with the broad bandwidth of incandescent lamps and thus are promising candidates for sources in spectroscopic applications requiring high brightness and broad bandwidth. Herein, near-infrared (IR) Fourier transform (FT) spectrometry with a supercontinuum (SC) light source is investigated. The efficient, collimated propagation of broad bandwidth SC light through an 18 m path length multipass cell is demonstrated. A normalized spectral difference is calculated for the SC spectrum on consecutive FT mirror scans and is found to vary by less than 0.5%, indicating excellent spectral stability. The rms noise on zero absorbance lines is obtained as a function of the number of mirror scans at 0.125, 2, and 16 cm−1 resolution for both the SC and conventional tungsten lamp source. The SC source has approximately a factor of ten times more noise than the lamp under comparable conditions for each resolution and data acquisition time. This clearly indicates that spectral acquisition with the SC source is not detector noise limited. NIR-FT spectra of methane and methyl salicylate, acquired with both the SC and lamp source, are reported. These spectra illustrate the advantage the SC source has over the incandescent source in that it can efficiently traverse long path lengths, thus providing a sensitivity advantage. The spectra also demonstrate the disadvantage of the SC source with respect to the lamp in the increased level of amplitude noise. Prospects for the future use of SC sources in absorption spectroscopy, including possible noise mitigation strategies, are briefly discussed.

Second-order coherence of supercontinuum light

Abstract: We analyze the coherence properties of supercontinuum generated in photonic crystal fibers by applying the second-order coherence theory of nonstationary light. Using an ensemble of simulated realizations, we construct two-frequency cross-spectral density and two-time mutual coherence functions. This allows us to introduce measures of temporal and spectral coherence. We show that, in the long-pulse regime, supercontinuum light can be decomposed into a sum of coherent and quasi-stationary contributions. Our approach and findings are also applicable in the short-pulse regime.