1,720,975 research outputs found
Light-induced reflectivity switching in gallium-on-silica films in the blue-green spectral region
No full textThe dynamics of the light-induced, reflectivity switching at a silica–gallium interface prepared by ultrafast pulsed laser deposition, is studied for the first time in the blue–green spectral region. A considerable interface reflectivity increase is seen at fluencies of about 1 mJ/cm2. The effect peaks at temperatures just below the gallium melting point (29.8 °C), while the reflectivity recovery times increase critically
Femtosecond cubic optical nonlinearity of thin nickel films
No full textTransient pump–probe measurements of circular anisotropy in nickel films induced by 38-fs optical pulses show an instantaneous response that is related to the optical orientation of the spins of free electrons. Measurements in a sample of variable thickness, performed in both transmission and reflection, revealed that the surface significantly influences the degenerate cubic optical nonlinearity of the nickel films to a depth of approximately 4–5 nm into the bulk
Cross-wavelength all-optical switching using nonlinearity of liquefying gallium
No full textThe gallium/silica interface optical nonlinearity associated with a light-induced structural phase transition from alpha-gallium to a more reflective, more metallic phase shows an exceptionally broadband spectral response. It allows 40% deep nanosecond/microsecond cross-wavelength intensity modulation between signals at 1.3 and 1.55µm
The light-induced structural phase transition in confining gallium and its photonic applications
No full textWe report on a study of the dynamics of a recently discovered light-induced, surface-assisted, structural phase transition from a common orthorhombic phase of α-gallium to a highly reflective phase that occurs at temperatures just below the metal's bulk melting point (30 °C). It is fully reversible with dynamics occurring on a nanosecond/microsecond time scale and can be stimulated by very low-intensity radiation, typically 10-5 W/µm². The two gallium phases involved have significantly different optical properties and this difference gives rise to a gigantic optical nonlinearity, χ(3) ~ 1 esu, that offers tremendous new opportunities for controlling light with light. The microscopic model of the effect is discussed
Light-induced specular-reflectivity suppression at a gallium/silica interface
No full textThe reflectivity of a gallium/silica interface formed on an optical flat or at the tip of a cleaved optical fiber can be reduced in a reversible fashion when the interface is excited by a few milliwatts of laser power. This phenomenon occurs at temperatures just below gallium's melting point. We believe that the effect can be attributed to light-induced structuring at the interface
Investigation of thermal stability of UV written planar waveguides using direct grating writing
No full textWe use the Direct Grating Writing technique, based on Direct UV writing, to define planar Bragg channel waveguides and accurately probe the refractive index to characterise thermal waveguide erasure and material properties
Gigantic broadband optical nonlinearity in gallium films deposited by ultrafast laser ablation
No full textGigantic broadband optical nonlinearity in gallium films deposited by ultrafast laser ablation
No full textGallium-Silica interfaces have emerged as a new type of structure that combines a strong nonlinearity [1] with picosend switching-on time [2]. Here we report that the optical nonlinearity of gallium films deposited on fused silica by ultrafast pulsed laser ablation is very broadband, spanning from 480 nm to 810 nm
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