APPARATUS FOR PROVIDING OPTICAL RADIATION

摘要

Apparatus (380) for providing optical radiation (381), which apparatus comprises a seed laser (382) for providing seeding radiation (387), at least one amplifier (383) for amplifying the seeding radiation (387), and a reflector (384), wherein the seed laser (382) is a Fabry Perot semiconductor laser, the seed laser (382) is connected to the amplifier (383) via the reflector (384), the reflector (384) is arranged to reflect a proportion (388) of the seeding radiation (387) emitted by file seed laser (382) back into the seed laser (382), and the amplifier (383) comprises an optical fibre (1) which comprises a core (3) having a refractive index n1 and a pedestal (4) having a refractive index n2, and wherein the optical fibre (1) includes a first cladding (5) made of glass having a refractive index n3 surrounding the pedestal (4), wherein n1 is greater than n2, and n2 is greater than n3.