Broadband fiber light source with high wavelength stability under radiation for IFOG applications

An interferometric fiber optic gyroscope, comprising:

• a rare-earth-doped-fiber light source configured to emit broadband amplified spontaneous emission with a stable mean wavelength, the rare-earth-doped-fiber light source including:
• an undoped fiber formed from a first host glass and having a length;
• a rare-earth doped fiber formed from a second host glass that is the same as first host-glass and having the same length as the undoped fiber, wherein the undoped fiber and the rare-earth doped fiber are placed in proximity to each other;
• a first coupler configured to direct a first portion of pump power from a pump laser to the undoped fiber, wherein the first portion of pump power was twice passed through the second coupler;
• and
• a wavelength division multiplexer configured to input a second portion of pump power from the pump laser to the rare-earth doped fiber;
• a second coupler configured to direct a first portion of the amplified spontaneous emission to an optical splitter and a second portion of the amplified spontaneous emission to a photodetector;
• the optical splitter operable to split the first portion of the amplified spontaneous emission into a clockwise optical beam and a counterclockwise beam;
• and
• a gyroscopic sensing coil communicatively coupled with the optical splitter, the gyroscopic sensing coil operable to output rate signals indicative of a rotation rate of the gyroscopic sensing coil.

A method to reduce impact of radiation on a mean wavelength of a rare-earth-doped-fiber light source, the method comprising:

• placing an undoped fiber in proximity with a rare-earth doped fiber, the undoped fiber having a same cross-sectional structure, and a same host material as the rare-earth doped fiber, the rare-earth doped fiber having rare-earth ions in a fiber core of the rare-earth doped fiber and the undoped fiber being independent of rare-earth ions in a fiber core of the undoped fiber;
• passing a pump beam from a pump laser through a coupler, wherein a first portion of the pump power is coupled into a first photodiode and a second portion of the pump power optically pumps the rare-earth doped fiber;
• coupling the pump power passed twice through the coupler to the undoped fiber;
• and
• detecting an output from the undoped fiber at a second photodiode.