Abstract: There is provided a complex frequency response filter providing a frequency response having a desired shape. A first complex frequency response filter includes a first and a second reflecting surfaces defining a resonant cavity therebetween. Each of the reflecting surfaces respectively has a predetermined surface finish providing a given reflectivity, therefore providing resonances with a predetermined shaped frequency response of a predetermined amplitude and of a predetermined periodicity. Those frequency responses can then be summed to generate an arbitrarily complex spectral response. In another embodiment, the complex frequency response filter includes a transmission medium and a first and a second reflecting surfaces defining a resonant cavity therebetween.

Abstract: A method and a system for filtering a user light beam using a periodic filter having a frequency response stabilized at an absolutely calibrated value are provided. A primary light beam is generated by a tunable laser source and portions thereof are filtered by an absolute reference filter and the periodic filter. First the frequency of the laser source is automatically locked on the absolute reference filter, and then the frequency response of the periodic filter is locked relative to the frequency of the laser source. The frequency response of the periodic filter is therefore continuously maintained at the proper calibration. User input and output are provided to pass the user light beam through the stabilized periodic filter independently of the filter stabilization process. A broadband absolutely calibrated optical source and a method for absolutely calibrating an optical spectrum analysis device are also provided.