Institute of Optical Materials and Technologies, Bulgarian Academy of Sciences, Acad. G. Bonchev, Bl. 109, 1113 Sofia, BulgariaTechnical University -Sofia and Plovdiv Branch, QOEL-Scientific Laboratory and Department of Laser Engineering, Sofia and Plovdiv, BulgariaTechnical University -Sofia and Plovdiv Branch, QOEL-Scientific Laboratory and Department of Laser Engineering, Sofia and Plovdiv, Bulgaria
Elena Stoykova;Marin Nenchev;Margarita Deneva
We have studied a structure composed from two wavelength tunable wedged interferometers and proved its potential for providing an increased free spectral range in comparison to a conventional interferential wedge. The interferential wedges with optical thickness from several micrometers to several hundred micrometers and apex angles of the order of tens microradians have been used. We have computed transmission for a monochromatic light beam with arbitrary wavefront using the angular spectrum approach for interferential wedges with different optical thicknesses and apex angles. We have conducted experiments with several stacks formed from different two wedges. Thus, we have confirmed selection of a single transmission resonance within the impact area of a large diameter beam instead of occurrence of multiple transmission peaks observed for a single interferential wedge. The stack enables wavelength tuning for a small diameter multi-wavelength beam in an increased spectral range at keeping high spectral resolution if the structure is formed by a thin and a thick interferential wedges. The experiments have shown that the selected transmission peak is narrowed spatially and spectrally at the expense of lower transmission, which is 50-60% of transmission provided by the used interferential wedges.