High Power Compact Single-Frequency Volume Bragg Er-Doped Fiber Laser

The purpose of this NASA SBIR Phase I proposal is to develop the prototype of a compact single-frequency mode – one longitudinal and one transverse mode – laser oscillator (SFM) using a pulse pumped Er-doped multimode fiber as an active element inserted in the external cavity. The main feature of the proposed design is the use of volume transmitting or reflecting Bragg gratings for longitudinal and transverse mode selection in an external laser resonator. The technical approach for the development such a laser is based on application a new type of robust optical element as one of the cavity mirrors, a volume Bragg grating recorded in photo-thermo-refractive (PTR) glass. The selectivity of volume Bragg gratings to wavelengths, angles of incidence and at certain conditions to the state of incident polarization could be successfully applied in design of a novel type of a laser resonator. The use of volume Bragg gratings for mode selection instead of conventional fiber Bragg gratings will result in decreasing of power density by several orders of magnitude and, therefore, will increase threshold of laser damage and other nonlinear processes dramatically.