Abstract-Currently, direct-write waveguide fabrication is probably the most widely studied application of femtosecond laser micromachining in transparent dielectrics. Devices such as buried waveguides, power splitters, couplers, gratings, and optical amplifiers have all been demonstrated. Waveguide properties depend critically on the sample material properties and writing laser characteristics. In this paper, we discuss the challenges facing researchers using the femtosecond laser direct-write technique with specific emphasis being placed on the suitability of fused silica and phosphate glass as device hosts for different applications.
Abstract:We study numerically depressed-index cladding, buried, micro-structured optical waveguides that can be formed in a lithium niobate crystal by femtosecond laser writing. We demonstrate to which extent the waveguiding properties can be controlled by the waveguide geometry at the relatively moderate induced refractive index contrasts that are typical of the direct femtosecond inscription.
In this paper, we report on the inscription of a 4th order fiber Bragg grating (FBG) made line-by-line (LBL) in the optical fiber using femtosecond (fs) laser. Strong Bragg resonance (~17dB) and low insertion loss (~0.5dB) were obtained with only 2000 periods. Measured refractive index change of these inscribed lines reaches up to 7×10 −3. The grating was fully characterized and the low insertion loss together with low polarization dependent loss were realized compared to the gratings made by the point-by-point (PBP) method. High temperature annealing experiment shows the grating can survive up to at least 800°C.
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