We investigated the physical and chemical properties of alicyclic methacrylate copolymers and their changes under deep-UV exposure. It was shown that alicyclic methacrylate copolymers have a better thermal stability and a higher refractive index than conventional poly(methyl methacrylate) (PMMA). Fourier transform IR (FTIR) spectra show the scission of the carbonyl group of the alicyclic methacrylate copolymers by deep-UV exposure similar to that of PMMA. This structural modification results in a local and controllable increase in refractive index in the exposed areas of the polymer surface. We fabricated polymer waveguides from alicyclic methacrylate copolymers by conventional photolithography using quartz/chromium mask. The minimum propagation loss of the straight waveguide with a 7.5 mm width was 2 dB/cm at 1550 nm.

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We have investigated the fabrication of waveguides from alicyclic methacrylate copolymer based on refractive-index modification by deep-UV exposure. By optimizing the UV-exposure process, we were able to obtain single-mode waveguides with a propagation loss of 0.8 dB/cm at 1550 nm, which is due only to material losses in this wavelength range. The loss obtained here is comparable with that of poly(methyl methacrylate) (PMMA) waveguides fabricated by deep-UV exposure. The fabricated waveguide is also single mode at 808 nm, and its propagation loss is 0.6 dB/cm. This alicyclic methacrylate copolymer is a promising material for the fabrication of polymer waveguides by use of deep-UV exposure.

We show that the 3D charged Banados-Teitelboim-Zanelli (BTZ) black hole solution interpolates between two different 2D AdS spacetimes: a near-extremal, nearhorizon AdS 2 geometry with constant dilaton and U(1) field and an asymptotic AdS 2 geometry with a linear dilaton. Thus, the charged BTZ black hole can be considered as interpolating between the two different formulations proposed until now for AdS 2 quantum gravity. In both cases the theory is the chiral half of a 2D CFT and describes, respectively, Brown-Hennaux-like boundary deformations and near-horizon excitations. The central charge c as of the asymptotic CFT is determined by 3D Newton constant G and the AdS length l, c as = 3l/G, whereas that of the near-horizon CFT also depends on the U(1) charge Q, c nh ∝ lQ/ √ G.