Thermal stability of microstructural and optical modifications induced in sapphire by ultrafast laser filamentation

Applied Surface Science

et al. 2013

a b s t r a c tIn this work the fabrication of buried optical waveguides by femtosecond laser inscription in the 0.8CaSiO 3 -0.2Ca 3 (PO 4 ) 2 eutectic glass doped with Nd 3+ ions is reported. The glass samples were prepared by melting the eutectic powder mixture in a Pt-10 wt.% Rh crucible at 1600 • C and pouring it in a preheated brass mould. Afterwards, the glass was annealed to release the inner stresses. Buried waveguides were fabricated by focusing beneath the surface a pulsed Ti:sapphire laser with a pulsewidth of 120 fs working at 1 kHz. Two adjacent parallel tracks were written to define a region where an increase in the refractive index occurs. The effects produced by the variation of the laser pulse energy as well as the lateral separation between tracks, scanning speed and focusing distance were studied. After the laser processing, the near-field intensity distribution at 633 nm of the waveguide's modes was studied demonstrating the confinement of both, the TE as the TM polarizations. In order to diminish the losses induced by colour centres absorption, heat treatments were carried out in the samples. The waveguide's modes were compared with respect to the samples without heat treatments. The spectroscopic properties of the neodymium ions have been characterized to evaluate in what extent their optical properties could be modified by the waveguide fabrication process and to elucidate the potential application of such waveguides as integrated laser sources.

Section: Resultsmentioning

confidence: 99%

Stress-induced buried waveguides in the 0.8CaSiO3–0.2Ca3(PO4)2 eutectic glass doped with Nd3+ ions

Sola

Mendibil

Applied Surface Science

et al. 2013

“…The propagation loss for single‐line vicinal waveguides is typically 2.5 dB/cm, and the dual‐line structures have 0.65 and 2 dB/cm for fs‐ or ps‐laser inscribed Ti:sapphire samples. In addition, for the UV fs‐laser inscribed single‐line Cr:sapphire waveguides, the guiding properties seem to be very stable at a thermal treatment below 600 ºC, whilst 1000 ºC annealing will completely erase the refractive‐index changes and the guidance . Figure depicts the dependence of the mode size on the thermal annealing treatment of single‐line Cr:sapphire Type II waveguides.…”

Section: Methodsmentioning

confidence: 99%

“…Ti‐doped sapphire is the gain media for broadband tunable laser systems under both CW and fs operation modes. Channel waveguides have been produced in Ti:sapphire and Cr:sapphire crystals by using the Type II approach . Fs‐laser pulses have used at IR wavelength as well as in the UV region.…”

Section: Methodsmentioning

confidence: 99%

Optical waveguides in crystalline dielectric materials produced by femtosecond‐laser micromachining

Chen

Laser & Photonics Reviews

2013

615

392

Femtosecond-laser micromachining (also known as inscription or writing) has been developed as one of the most efficient techniques for direct three-dimensional microfabrication of transparent optical materials. In integrated photonics, by using direct writing of femtosecond/ultrafast laser pulses, optical waveguides can be produced in a wide variety of optical materials. With diverse parameters, the formed waveguides may possess different configurations. This paper focuses on crystalline dielectric materials, and is a review of the state-of-the-art in the fabrication, characterization and applications of femtosecondlaser micromachined waveguiding structures in optical crystals and ceramics. A brief outlook is presented by focusing on a few potential spotlights.

“…[27][28][29] In this way, 30-min isochronal annealings have been applied starting from 200 C up to 750 C with steps of 50 C. After each treatment, the propagation losses have been determined by measuring the transmitted power along the waveguide. Besides, the intensity distribution of the guided modes has been measured using a CCD camera.…”

Section: Resultsmentioning

confidence: 99%

Ultrafast direct laser writing of cladding waveguides in the 0.8CaSiO3-0.2Ca3(PO4)2 eutectic glass doped with Nd3+ ions

Mendívil

Sola

Journal of Applied Physics

et al. 2015

We report on tubular cladding optical waveguides fabricated in Neodymium doped WollastoniteTricalcium Phosphate glass in the eutectic composition. The glass samples were prepared by melting the eutectic powder mixture in a Pt-Rh crucible at 1600 C and pouring it in a preheated brass mould. Afterwards, the glass was annealed to relieve the inner stresses. Cladding waveguides were fabricated by focusing beneath the sample surface using a pulsed Ti:sapphire laser with a pulsewidth of 120 fs working at 1 kHz. The optical properties of these waveguides have been assessed in terms of near-field intensity distribution and transmitted power, and these results have been compared to previously reported waveguides with double-line configuration. Optical properties have also been studied as function of the temperature. Heat treatments up to 700 C were carried out to diminish colour centre losses where waveguide's modes and transmitted power were compared in order to establish the annealing temperature at which the optimal optical properties were reached. Laser experiments are in progress to evaluate the ability of the waveguides for 1064 nm laser light generation under 800 nm optical pumping. V C 2015 AIP Publishing LLC.