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.