A method for preparing all-solid-state photonic crystal fiber preform by extrusion by aligning the center of the first jacking end of the first jacking rod with the center of the core outlet mold. The adverse effect on this part of extruded core glass by oxygen or other impurities in air during the extrusion out of the core outlets can be avoided. The defects on the core glass surface and the cladding glass surface can be effectively removed, and the purity and quality of the core component in the obtained fiber preform can be improved.

The present invention discloses a method for preparing all-solid-state photonic crystal fiber preform by extrusion. Firstly, aligning the center of the first jacking end of the first jacking rod with the center of the core outlet mold. The adverse effect on this part of extruded core glass by oxygen or other impurities in air during the extrusion out of the core outlets can be avoided. The defects on the core glass surface and the cladding glass surface can be effectively removed, and the purity and quality of the core component in the obtained fiber preform can be improved.

A microheater comprises an optical fiber including a rare earth-doped glass core surrounded by a glass cladding. The rare earth-doped glass core comprises a rare earth dopant at a concentration sufficient for luminescence quenching such that, when the rare earth dopant is pumped with light at an absorption band wavelength, at least about 90% of absorbed pump light is converted into heat.