Optical fiber diffraction grating, a method of fabricating thereof and a laser light source

A method of manufacturing an optical fiber diffraction grating, comprising:

• the first step of drawing an optical fiber preform to form an optical fiber having a positive thermal expansion coefficient within an operating temperature range;
• the second step of forming a diffraction grating portion by changing at least a refractive index of a core along an optical axis of said optical fiber;
• and
• the third step of extruding a liquid crystal polymer material having a negative thermal expansion coefficient within the operating temperature range around said optical fiber having said diffraction grating portion, and forming a first coating portion made of the liquid crystal polymer and concentrically surrounding said optical fiber.

A method of manufacturing an optical fiber diffraction grating, comprising:

• the first step of drawing an optical fiber preform to form an optical fiber having a positive thermal expansion coefficient within an operating temperature range;
• the second step of forming a second coating portion around said optical fiber to concentrically surround said optical fiber;
• the third step of forming a diffraction grating by changing at least a refractive index of a core along an optical axis in an exposed portion of said optical fiber after said second coating portion is partly peeled off;
• the fourth step of forming said second coating portion again around said optical fiber having said diffraction grating portion;
• and
• the fifth step of extruding a liquid crystal polymer having a negative thermal expansion coefficient within the operating temperature range around said second coating portion covering said optical fiber, and forming a first coating portion made of the liquid crystal polymer and concentrically surrounding said optical fiber.