Quantum wave-converter
A plug-and-play fiber-coupled nonlinear optical quantum wave-converter, optimized for quantum communications, comprises a commercial periodically-poled, waveguide-based, nonlinear optical chip, coupled with a pair of substrate-guided holographic (SGH) wavelength division multiplexers (WDM) and a pair of SGH filters; it offers bidirectional difference frequency conversion (DFG) and sum frequency conversion (SFG) simultaneously in a single packaged device.
1. A secure quantum communications system comprising:
(a) a first light beam comprising a first wavelength from a first optical source to a first hologram adjacent to one end of a substrate-guided-holographic waveguide;
(b) a second light beam comprising a second wavelength different than the first wavelength from a second optical source to a second hologram adjacent to an opposite end of the waveguide;
(c) a third hologram attached to the center of the waveguide;
wherein the first and second light beams bounce from their respective holograms and travel through the waveguide to combine through a third hologram are focused to a point outside the waveguide;
wherein the substrate-guided-holographic waveguide comprises a periodically-poled nonlinear optical device;
wherein the sum frequency generator and difference frequency generator are combined in a single unit;
wherein at least one of the optical sources comprises a laser; and
wherein the substrate-guided-holographic waveguide comprises a spectral filter with a bandpass comprising a target wavelength so only the target wavelength is output.
2. The system of claim 1 wherein the first wavelength comprises a short-wave infrared pump and the second wavelength comprises a quantum signal for difference frequency generation and a telecommunications-band signal for sum frequency generation.
3. The system of claim 1 including the use of optical fibers as inputs and outputs.
4. The system of claim 1 wherein a nonlinear mixing efficiency of the waveguide is nearly exponentially proportional to a quasi-matched interaction length of the waveguide.
5. The system of claim 1 wherein the first and second holograms comprise a thick holographic optical element.
6. The system of claim 1 wherein the holograms include optical power.
7. The system of claim 1 wherein the waveguide comprises a single bidirectional device performing both difference frequency generation and sum frequency generation.
8. The system of claim 1 wherein the third hologram comprises a multiplexed lens, a separated lens, a multiplexed grating, or a separated grating.