Patent ID: 6934033

Claim:
A wavelength reference apparatus for use in calibrating a device comprising a tunable Fabry-Perot filter or a tunable VCSEL, the wavelength reference apparatus being configured to tune the device to a precise, known wavelength, the wavelength reference apparatus comprising; an LED, the LED having an emission profile which varies with wavelength; an etalon, where the etalon is chosen so as to have a transmission profile which comprises a comb of transmission peaks, with each transmission peak occurring at a precise, known wavelength; a detector for detecting the light emitted by said LED and passing through said etalon; and the device being positioned between said etalon and said detector, and the device being swept through its tuning range by varying the tuning voltage applied to the device, the known transmission wavelengths established by said LED and said etalon are correlated to counterpart tuning voltages of the device so as to calibrate the device.