Direct laser written waveguide coupler with an optically tunable splitting ratio
Frontiers in Ultrafast Optics : Biomedical, Scientific, and Industrial Applications (11th : 2011) (23 - 26 January 2011 : San Francisco, CA)
Heisterkamp, Alexander; Neev, Joseph and Nolte, Stefan. Frontiers in ultrafast optics : biomedical, scientific, and industrial applications XI : 23-26 January 2011, San Francisco, California, United States, p.79250K-1-79250K-5
The femtosecond laser direct-write technique was used to create a 2x2 single-mode waveguide coupler in Yb-doped borosilicate glass. Initial modelling demonstrates that a reversible change in splitting ratio at 800 nm of more than 20% is possible (i.e. 50:50 to 30:70) if a shift in refractive index of the order of 1×10⁻⁴ can be induced. Such a shift is expected to be achieved through resonant optical excitation at 976 nm of the ytterbium ions, which increases the refractive index through heating and the direct pumping of a saturable optical absorption.