Abstract: A method for creating direct band gap material from indirect band gap material, the resultant direct band gap material, and corresponding optical devices are described. The method employs atomic layer doping (ALDo) to create closely spaced ?-doped layers, alternating between n-type and p-type dopants, to modify the band structure of the indirect band gap material. The spacing between adjacent ?-doped layers is between 1 and 100 ?. The dopants may, for example, include phosphorus, boron, and/or aluminum, while the indirect band gap material may, for example, include silicon and/or germanium. The method and material may alternatively employ a single dopant for all closely spaced ?-doped layers. This single dopant may, for example, be erbium. Optical devices, including emitters and photodetectors, may be formed of the created direct band gap material. Both vertical and lateral devices may be formed.

Abstract: A system and method are provided for optical homodyne detection in an optical fiber interferometer. A detection signal is obtained by interfering an optical data signal with a phase-modulated optical reference signal. The modulator for the optical reference signal is phase-locked to an oscillatory modulation waveform. In embodiments, the modulator includes a piezoelectric element. In more specific embodiments, the modulator is a piezoelectric optical fiber-stretcher.

Abstract: In a method of atomic precision advanced manufacturing (APAM), an atomic or molecular resist layer on a substrate surface is selectively depassivated by locally exciting the substrate surface with an optical beam effective to eject adsorbed atoms or molecules from the substrate surface. The substrate surface is further processed by exposing it to a precursor gas, decomposing the precursor gas to release a dopant, and incorporating the dopant into the substrate surface.