0000000000383181
AUTHOR
A. Ortigosa-blanch
Tapering photonic crystal fibres for supercontinuum generation with nanosecond pulses at 532nm
Experimental results on supercontinuum generation in photonic crystal fibre tapers using pump pulses of 7 ns duration at 532 nm are presented. Photonic crystal fibre tapers with the first wavelength of zero dispersion around 532 nm were fabricated. The generation of supercontinuum was investigated in normal and anomalous dispersion regimes. Supercontinuum spectra spanning more than 400 nm in the visible region are reported.
Wavelength-codified fiber laser hydrogen detector
We report a scheme for an optical hydrogen detector that codifies the information in wavelength. The system is based on an erbium-doped fiber laser with two coupled cavities and a Palladium-coated tapered fiber within one of the laser cavities. The tapered fiber acts as the hydrogen-sensing element. When the sensing element is exposed to a hydrogen atmosphere, its attenuation decreases changing the cavity losses. This change leads the system to switch lasing from the wavelength of the auxiliary cavity to the characteristic wavelength of the cavity which contains the sensing element. The detection level can be shifted by adjusting the reflective elements of the cavity containing the sensing …
Analytical evaluation of chromatic dispersion in photonic crystal fibers
We present a two-dimensional modal approach for the evaluation, in an analytical manner, of chromatic dispersion in any kind of optical fiber. It combines an iterative Fourier technique to compute the propagation constant at any fixed wavelength and an analytical procedure to calculate its derivatives. The proposed formulation takes into account the effective anisotropy of the interfaces and allows us to deal with microstructured fibers, in general, and specifically with realistic photonic crystal fibers (PCFs), including arbitrary spatial refractive-index distributions of dispersive and absorbing materials. This fast and accurate numerical technique is extremely useful for both analysis an…
Time-domain fiber laser hydrogen sensor.
We report a novel scheme for a fiber-optic hydrogen sensor based on an erbium-doped fiber laser with a palladium-coated tapered fiber within the laser cavity. The tapered fiber acts as a hydrogen-sensing element. When the sensing element is exposed to a hydrogen atmosphere, its attenuation decreases, changing the cavity losses and leading to a modification of the laser transient. The hydrogen concentration is obtained by simple measurement of the buildup time of the laser. This technique translates the measurement of hydrogen concentration into the time domain, and it can be extended to many intensity-based fiber sensors. Relative variations in the buildup time of up to 55% at an increase o…
Temperature independence of birefringence and group velocity dispersion in photonic crystal fibres
Experimental results are presented for the dependence of the dispersion and the birefringence of a highly birefringent photonic crystal fibre with temperature. It is shown that, unlike conventional optical fibres, where temperature induces stress regions between the different materials present in their structure, photonic crystal fibres exhibit no dependence with temperature of these optical properties owing to the single material nature of their structures.