Optical fiber wavelength reference device

Abstract

An optical fiber wavelength reference device for tuning a tunable Fabry-Perot filter and/or a tunable VCSEL to a desired frequency, where the device uses a fiber etalon to generate a pattern of reference frequencies against which the device is tuned.

What is claimed is:  
     
         1 . A wavelength reference apparatus for use in calibrating a tunable Fabry-Perot filter or a tunable VCSEL to a precise, absolute frequency on a target frequency grid, the wavelength reference apparatus comprising: 
 a fiber etalon wherein the fiber etalon is chosen so as to have a FSR significantly less than the target frequency grid, whereby when monotonic light is swept through the fiber etalon, the transmission peaks established by the fiber etalon will surround, and have much less spacing, than the target reference grid; and    a detector for detecting the transmission peaks established by the fiber etalon.    
     
     
         2 . A wavelength-locking apparatus for use in tuning a tunable Fabry-Perot filter or a tunable VCSEL to a precise, absolute frequency on a target frequency grid, the wavelength locking apparatus comprising: 
 a fiber etalon, wherein the fiber etalon is chosen so as to have a FSR significantly less than the target frequency grid, whereby when monotonic light is swept through the fiber etalon, the transmission peaks established by the fiber etalon will surround, and have much less spacing, than the target reference grid;    a detector for detecting the transmission peaks established by the fiber etalon; and    a controller for tuning the wavelength of the device by monitoring the transmission peaks of the fiber etalon.    
     
     
         3 . A method for tuning a tunable Fabry-Perot filter or a tunable VCSEL, comprising the steps of: 
 (1) sweeping light from the device through a fiber etalon in a monotonic manner so as to generate an inline comb of optical transmission peaks, the fiber etalon being chosen so that the spacing of its transmission peaks is significantly less than the spacing of the desired target frequencies;    (2) identifying the frequency of one of the transmission peaks of the fiber etalon; and    (3) monitoring the output of the fiber etalon as the device is tuned so as to tune the device to the desired frequency.