Supercontinuum generation in photonic crystal fibers

Contact:
Researcher Uffe Visbech Møller, Office: 345V/276, telephone: 4525 5706, email: ufmo@fotonik.dtu.dk  

The term supercontinuum does not cover a specific phenomenon but rather a plethora of nonlinear effect leading to considerable spectral broadening of optical pulses and thereby potentially octave-spanning output.

Supercontinuum light can be best described as ‘broad as a lamp, bright as a laser’. Incandescent and fluorescent lamps, such as those made from tungsten halogens or xenon, provide a very broad spectrum, typically 400-1,700 nm, but the intensity is limited to the quality of the filament or the efficiency of the gas excitation. Furthermore, as the light is not spatially coherent, coupling the light into the fiber is challenging, resulting in a low-power, low-brightness source with mediocre beam quality.

Lasers on the other hand have high spatial coherence and very high brightness, which enables optimum coupling to a fiber and outstanding single-mode beam quality. However, lasers are usually monochromatic, and thus if more than one wavelength is required extra lasers a specific wavelengths are required to cover a broad spectrum. A supercontinuum source bridges this gap, providing an ultrabroadband white-light spectrum, typically 500-2400 nm, with single-mode beam characteristics and excellent pointing stability and the brightness of a laser.

Photonic crystal fibers are ideal media for supercontinuum generation as the dispersion can be designed to facilitate continuum generation in a specific region. In this way it is possible to convert light to both higher and lower wavelength.

In this project we will do:

·         Both experimental and numerical work

·         Generate and characterize supercontinuum in photonic  crystal fibers

·         Fiber characterization by loss measurements

·         Noise characterization of the supercontinuum light source

Maximum number of students: 3