Low bend loss waveguides enable compact, efficient 3D photonic chips
ABSTRACT We present a novel method to fabricate low bend loss femtosecond-laser written waveguides that exploits the differential thermal stabilities of laser induced refractive index modifications. The technique consists of a two-step process; the first involves fabricating large multimode waveguides, while the second step consists of a thermal post-annealing process, which erases the outer ring of the refractive index profile, enabling single mode operation in the C-band. By using this procedure we report waveguides with sharp bends (down to 16.6 mm radius) and high (80%) normalized throughputs. This procedure was used to fabricate an efficient 3D, photonic device known as a "pupil-remapper" with negligible bend losses for the first time. The process will also allow for complex chips, based on 10's - 100's of waveguides to be realized in a compact foot print with short fabrication times.
Full-textDOI: · Available from: Alexander Arriola, Mar 22, 2014
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ABSTRACT: Abstract. We report on waveguide lasers at 1064.5 nm in femtosecond laser-written double-cladding waveguides in Nd:GdVO4 crystals. The cladding waveguides guide both transverse electric (TE)- and transverse magnetic (TM)-polarized modes with considerably symmetric single-modal profiles and show good transmission properties (propagation loss as low as 1.0 dB/cm). The detailed structure of the single and double claddings has been imaged by means of μ-Raman analysis, and the observed slight fabrication asymmetries with respect to an ideal circular cladding are in well agreement with the observed differences in TE/TM propagation losses. Importantly, the Raman imaging shows the complete absence of lattice defect at the laser active volume. Under the optical pumping at 808 nm, a maximum output power up to 0.43 W of the continuous wave waveguide laser with a slope efficiency of 52.3% has been achieved in the double-cladding waveguide, which is 21.6% and 23% higher than that from a single-inner cladding waveguide. Furthermore, the maximum output power of the waveguide laser is 72% higher than that of the double-line waveguide due to the double-cladding design.Optical Engineering 09/2014; 53(9-9):097105. DOI:10.1117/1.OE.53.9.097105 · 0.96 Impact Factor
Journal of Lightwave Technology 03/2015; 33(6):1147-1154. DOI:10.1109/JLT.2014.2370673 · 2.86 Impact Factor
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ABSTRACT: Asymmetric mode-selective couplers for multiplexing the LP11 modes of an optical fiber fabricated by the femtosecond laser direct-write technique are demonstrated. The devices feature high coupling ratios, excellent mode extinction ratios and low insertion losses.Optical Fiber Communication Conference, Los Angeles, California United States; 03/2015