Coherent and spectral beam combining in thulium doped fiber laser and amplifier array

We will investigate the ways of increasing radiance of thulium doped fiber lasers using spectral and coherent beam combining techniques. We propose to employ the Fox-Smith resonator made of single mode large mode area fibers  for self-organized coherent beam combining in spectral region of 2000 nm. Further, we propose new scheme of spectral beam combining. The beam is spectrally decomposed to four beamlets on a diffraction grating. After individual amplification in double-pass thulium doped fiber amplifiers, the beamlets are assembled on the same grating. The proposed techniques of coherent and spectral beam combining will allow to achieve the power of 120 W in diffraction limited beam at a wavelength of 2000 nm.