A photonic band gap (PBG) device is provided for frequency up and/or down-converting first and second photonic signals incident on the device to produce a down-converted output photonic signal. When the first and second incident photonic signals have respective first and second frequencies &ohgr;3 and &ohgr;2, the down-converted photonic signal has a third frequency &ohgr;1=&ohgr;3−&ohgr;2. When the first incident field has a frequency &ohgr;1, the first up-converted photonic signal has a second frequency &ohgr;2. The second up-converted photonic signal has a third frequency &ohgr;3=&ohgr;1+&ohgr;2. Thus, the PBG device can be used to generate coherent near- and mid-IR signals by frequency down-converting photonic signals from readily available photonic signal sources, or red, blue, and ultraviolet signals by up-converting the same readily available photonic signal sources.