Localized hyperthermia therapy involves heating a small volume of tissue in order to kill cancerous cells selectively and with limited damage to healthy cells and surrounding tissue. However, these features are only achievable through real-time control of the tissue temperature and heated volume, both of which are difficult to obtain with current heating systems and techniques. This work introduces an optical fiber-based active heater that acts both as a miniature heat source and as a thermometer.
View Article and Find Full Text PDFThe impact of sample orientation on the poling of single-sided multilayer silica structures is studied. The results show that the presence of a multilayer stack near the cathode creates a nonlinear region where it otherwise would not have formed. It is shown that field orientation impacts the location and magnitude of the induced nonlinearity.
View Article and Find Full Text PDFWe present, for the first time to our knowledge, a dual strain/temperature sapphire fiber Bragg grating sensor. Temperature and strain coefficients of the grating are evaluated. By recording the blackbody radiation level above 650 degrees C, wavelength shifts due to temperature can be decoupled from those due to strain.
View Article and Find Full Text PDFType I infrared ultrafast laser induced fiber Bragg gratings have been shown to exhibit higher-order resonances related to the Fourier components possessed by their nonsinusoidal index change profile. Using successive higher-order phase masks, we determine the Fourier components of type I-IR gratings in both hydrogen-loaded and unloaded fiber. Knowledge of the relative dc and ac components of a fiber Bragg grating is required for tailoring its spectral response.
View Article and Find Full Text PDFThe formation of two grating types in SMF-28 fiber by focusing 125 fs, 0.5-2 mJ pulses through a phase mask onto a fiber sample is studied. The first type, specified as type I-IR, occurs below the damage threshold of the medium.
View Article and Find Full Text PDFThe threshold for the fabrication of fiber Bragg gratings with ultrafast 800-nm radiation and a phase mask was studied in SMF-28 and all-silica core fiber by use of 125-fs pulses. High-pressure molecular hydrogen loading (H2 loading) was observed to significantly lower the grating writing threshold in standard Ge-doped telecommunication fiber. No reduction was observed with all-silica core fiber.
View Article and Find Full Text PDFHigh-quality retroreflecting fiber Bragg gratings were written in standard Ge-doped telecom fiber (Corning SMF-28) after a few minutes exposure with pulsed 800-nm, 120-fs laser radiation by use of a deep-etch silica zero-order nulled phase mask optimized for 800 nm. Induced index modulations of 1.9 x 10(-3) were achieved with peak power intensities of 1.
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