High-frequency gratings with rectangular-groove profiles are used to generate high-efficiency beam splitters and beam deflectors. The effects of the grating design parameters, i.e., period, groove depth, duty cycle, number of phase levels, and polarization state (TE and TM) of the incoming signal, are considered. The case of the binary beam splitter grating is analyzed by using rigorous electromagnetic grating analysis. Fabrication techniques are presented in which three different lithographic techniques are considered (optical contact, deep-UV stepper reduction, and electron-beam direct write). Experimental results of 97% efficiency for the beam splitter grating and up to 80% for the beam deflector grating are reported.

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An asymmetric semiconductor electron wave Fabry–Perot interference filter has been designed with two above-barrier quasibound states for optical transitions. The upper state was designed to have a spatial confinement lifetime greater than three times that of the lower state (which was designed to be less than 100 fs). Such lifetime ratios and magnitudes, which are nearly impossible for below-barrier states, satisfy the criteria required for achieving population inversion. Furthermore, the transitions were designed to have large dipole matrix elements. Absorption measurements at multiple temperatures were used to demonstrate the first bound-to-quasibound transitions in an asymmetric structure. The experimental energies and dipole matrix elements are in agreement with calculated values. This type of structure could represent the basis for a new room-temperature infrared semiconductor laser.

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