Abstract: To provide a surface treatment method for smoothing the surface of a ceramic thermal spray coating, and a ceramic thermal spray coating subjected to the surface smoothing treatment. A surface treatment method for a ceramic thermal spray coating, which comprises jetting a slurry containing a liquid having a viscosity at a temperature of 20° C. of 10 mPa/s or lower and a powder medium having a polyhedral structure and having a median diameter (D50) of from 1 to 50 ?m with a content of the powder medium of from 1 to 50 vol %, against a surface of a ceramic thermal spray coating, using a compressed gas under a pressure of from 0.01 to 1.0 MPa, to smooth the surface of the ceramic thermal spray coating.

Abstract: An optical device includes a core, a first cladding, a second cladding, a slanted fiber Bragg grating, and a high refractive index material. The first cladding covers the core and has a lower refractive index than the core. The second cladding covers the first cladding and has a lower refractive index than the first cladding. The slanted fiber Bragg grating is formed in the core and couples stimulated Raman scattering light, propagating through the core, to the first cladding. The high refractive index material has a higher refractive index than the second cladding and covers an outer peripheral surface of a removal portion where the second cladding is removed and a portion of the first cladding that covers the region where the slanted fiber Bragg grating is formed in the core.

Abstract: A method for setting a heating condition for thermal aging of each of fiber Bragg gratings, includes: determining, based on a correspondence ?(Ed) between a temperature coefficient ? of each of the fiber Bragg gratings and a demarcation energy Ed of each of the fiber Bragg gratings, a first lower limit Edmin of the demarcation energy Ed such that the temperature coefficient ? is not more than a desired upper limit ?max; and setting the heating condition for thermal aging of each of the fiber Bragg gratings such that the demarcation energy Ed is not less than the first lower limit Edmin.