A tunable resonant tunneling gap for resonant tunneling across the tunneling gap. By adjusting the width of the tunneling gap and adjusting an angle of incidence of light onto the tunneling gap, a pass-band shape and center wavelength may be tuned. The tunneling gap may be an air gap between lenses coated with matching Bragg reflectors. The air gap may be adjusted for example using piezo actuators connecting between the lenses. The angle of incidence may be adjusted for example by rotating the lenses, and thus the tunneling gap, relative to an incident beam of light.