Mid-infrared channel waveguides in RbPb 2 Cl 5 crystal inscribed by femtosecond laser pulses

Tubular cladding waveguide was inscribed in crystal volume by a femtosecond laser operating at 0.8µm. The waveguide sustains a single leaking mode at wavelength of 3.39µm. Propagation losses were investigated experimentally and theoretically at wavelengths of 1.58µm and 3.39µm. Measured losses were found to be as low as 1.4dB/cm at 1.58µm and 5.1dB/cm at 3.39µm. Complex propagation constants for leaking modes were obtained by numerical mode analysis. It was found, that mode leakage is a major factor of losses at wavelength of 3.39µm.