Spectral selectivity of systems formed by tunnel-coupled waveguides with very different parameters

An investigation was made of the spectral dependences of the transmission of a system of tunnel-coupled waveguides with very different parameters. It was established that smooth variation of the thickness of a buffer layer in such a structure influenced the spectral properties of the system as a whole. It was demonstrated experimentally that the transmission of the system was determined by the existence of a ‘transmission’ guided mode. A simple physical interpretation of the operation of a number of integrated and fibre-optic devices is put forward and it is shown that the use of the investigated structure of two tunnel-coupled waveguides is a promising way of constructing a microlaser with a waveguide output.