Mode Sorter Research Articles

Mode sorter and detector based on photon orbital angular momentum

Photons were generated possessing orbital angular momentum (OAM) in the form of Laguerre-Gaussian (LG) laser modes. Three Mach-Zehnder interferometer systems, with the use of Dove prisms, were constructed to sort and detect the LG modes based on their OAM state. Successful generating, sorting, and detecting of LG modes is the first step towards information encoding and decoding via lasers. It is possible to generate many LG modes, which can be orthogonally decoded. With many modes to encode information with it is possible to transfer more than one bit of information with a single photon using LG encoding. An experimental test of this concept was performed by demonstrating the generation and sorting of LG modes with attenuated intensities averaging below one photon passing through the system at a time. In summary, generating, sorting, and low-power detecting of specific LG modes were all demonstrated.

Self-adaptive current mode sorter with high resolution

A novel self-adaptive current mode sorter is presented. It has a simple structure with a complexity of O(N) and a large dynamic range. No-biasing signal is needed. It performs well even at large input currents. HSPICE simulation shows that this sorter has high precision, high resolution and low power.

Mode Theory of Multiterminal Transducer Chains

The mode concept is applied to the analysis of linear multiterminal transducers, operating at a discrete frequency. The transfer matrix of the most general transducer is considered, restrictions of reciprocity, symmetry and losslessness being introduced as special cases. A classification of proper modes of signal transmission into reactive, pseudo-active and power-handling modes is attempted. Single and multiple mode operation is investigated and a mode-sorter termination is described for the latter. Investigation of special multiterminal transducers shows that qualitative restrictions like losslessness and reciprocity impose orthogonality relations among the modes, whereas configurative restrictions like symmetry and reciprocity reduce the complexity of the problem by constraining the modes into pairs having reciprocal properties. An example is provided to indicate the possibility of pseudo-active, growing modes in lossless nonreciprocal transducers. Mode sorters are shown to be realizable as transformer banks in symmetrical chains.