Provided is a process for producing a wavelength conversion member which can suppress the reaction between inorganic nanophosphor particles and glass to suppress the deterioration of the inorganic nanophosphor particles, and the wavelength conversion member. The process for producing a wavelength conversion member includes the steps of: preparing inorganic nanophosphor particles 1 with an organic protective film formed on respective surfaces thereof; and mixing the inorganic nanophosphor particles 1 with glass powder and firing a resultant mixture in a temperature range where the organic protective films remain as retained films 3.

The present invention is generally directed to a photonic bad gap fiber and/or fiber preform with a central structured region comprising a first non-silica based glass and a jacket comprising a second non-silica based glass surrounding the central structured region, where the Littleton softening temperature of the second glass is at least one but no more than ten degrees Celsius lower than the Littleton softening temperature of the first glass, or where the base ten logarithm of the glass viscosity in poise of the second glass is at least 0.01 but no more than 2 lower than the base ten logarithm of the glass viscosity in poise of the first glass at a fiber draw temperature. Also disclosed is a method of making a photonic bad gap fiber and/or fiber preform.