Cascading of tunable optical filter elements

Abstract

A tunable optical signal device and method of using the same having at least two filter elements, each of said filter elements being made of a material having an adjustable parameter, wherein the adjustable parameter is maintained at slightly different values for adjacent filter elements.

What is claimed:  
     
         1 . A tunable optical signal device comprising at least two filter elements, each of said filter elements being made of a material having an adjustable parameter, and means for maintaining said adjustable parameter at slightly different values for adjacent filter elements.  
     
     
         2 . The tunable optical signal device of    claim 1    wherein the adjustable parameter is selected from temperature and mechanical stress.  
     
     
         3 . The tunable optical signal device of    claim 1    wherein the filter elements are Mach-Zehnder interferometers integrated with tunable Bragg gratings.  
     
     
         4 . The tunable optical signal device of    claim 1    wherein the material is a thermosensitive material.  
     
     
         5 . The tunable optical signal device of    claim 4    wherein the thermosensitive material is at least one thermosensitive polymer.  
     
     
         6 . The tunable optical signal device of    claim 1    wherein the adjustable parameter is temperature, said means for maintaining the adjustable parameter comprising: 
 a) a thermocouple for measuring the temperature of the material;  
 b) a temperature sensor for comparing the temperature of the material to a preset temperature; and  
 c) a heater for applying heat to the material to maintain said preset temperature.  
 
     
     
         7 . The tunable optical signal device of    claim 1    further comprising a circulator and a tunable Bragg grating.  
     
     
         8 . The tunable optical signal device of    claim 1    further comprising a plurality of narrow band mirrors, each mirror segregating a set of a plurality of wavelength signals and directing said set of wavelength signals to said filter element.  
     
     
         9 . The tunable optical signal device of    claim 9    further comprising GRIN lenses for collimating said set of wavelength signals before said set of wavelength signals enter the filter element.  
     
     
         10 . A method of dropping/adding at least one preselected wavelength of light from/to an optical signal comprising passing said optical signal through a tunable optical signal device comprising at least two filter elements, each of said filter elements being made of a material having an adjustable parameter, and means for maintaining said adjustable parameter at slightly different values for adjacent filter elements, said method comprising adjusting said parameter to reflect said at least one preselected wavelength of light.