All-optical signal processing method and device

Abstract

A method and an optical device in all-optical signal processing. It provides a novel way of taking into use the potential bandpass filtering capabilities of an optical complex one-pole resonator by, 1) excitating with at least part of the input signal an optical resonator arrangement that comprises two substantially parallel, independent, complex one-pole resonators arranged in a manner that one of the resonators is matched, and the other one is non-matched with the input signal, and 2) based on polarization separating further from the output of the optical resonator arrangement at least one optical output signal so that both the matched and non-matched resonators contribute to the formation of the output signal. The method and device can be utilized, for example, for optical signal analysis, optical clock recovery, or for producing high-frequency outputs from lower frequency input signals, like e.g. optical microwave generation.

1 . A method in optical signal processing of an optical input signal, wherein the processing of said input signal comprises: 
 excitating with at least part of said input signal an optical resonator arrangement that comprises at least two substantially parallel, independent, complex one-pole resonators arranged in a manner that the first one of said resonators is matched with the wavelength of the input signal and the second one is non-matched with the wavelength of the input signal, and    forming at least one optical output signal so that both said first and second resonators of said optical resonator arrangement contribute to the formation of said output signal.    
     
     
         2 . The method according to  claim 1 , wherein the imaginary part of the non-matched electric field corresponding to said second resonator is supressed.  
     
     
         3 . The method according to  claim 1 , wherein the optical input signal is substantially coherent and mode-locked with the optical resonator arrangement.  
     
     
         4 . The method according to  claim 1 , wherein said resonator arrangement is substantially a a single resonator cavity where said independent first and second resonators are formed as intracavity resonators within said single cavity based on the birefringency of said single cavity.  
     
     
         5 . The method according to  claim 1 , wherein said method is applied to generate a higher frequency optical output signal from a lower frequency optical input signal.  
     
     
         6 . The method according to  claim 1 , wherein said method is applied to all-optical clock recovery.  
     
     
         7 . The method according to  claim 1 , wherein said method is applied to analyze the signal frequency components of an optical input signal.  
     
     
         8 . The method according to  claim 5 , wherein said method is applied to generate output signal in microwave or higher frequency range.  
     
     
         9 . The method according to  claim 4 , wherein said method is applied to the measurement of birefringency of said optical resonator arrangement.  
     
     
         10 . An optical device for optical signal processing of an optical input signal, wherein for the processing of said input signal the device comprises: 
 an optical resonator arrangement excitated with at least part of said input signal and comprising at least two, substantially parallel, independent, complex one-pole resonators arranged in a manner that the first one of said resonators is matched with the wavelength of the input signal and the second one is non-matched with the wavelength of the input signal, and    combining means to combine the outputs.    
     
     
         11 . The optical device according to  claim 10 , wherein the imaginary part of the non- matched electric field corresponding to said second resonator is arranged to be supressed.  
     
     
         12 . The optical device according to  claim 10 , wherein the optical input signal is arranged to be substantially coherent and mode-locked with the optical resonator arrangement.  
     
     
         13 . The optical device according to  claim 10 , wherein said resonator arrangement is substantially a single resonator cavity where said independent first and second resonators are formed as intracavity resonators within said single cavity based on the birefringency of the said single cavity.  
     
     
         14 . The optical device according to  claim 10 , wherein said optical resonator arrangement comprises one or more Fabry-Perot type resonators in which the optical medium of such a single resonator is arranged between cavity forming reflecting means.  
     
     
         15 . The optical device according to  claim 10 , wherein said optical resonator arrangement comprises one or more loop or ring type resonators in which the optical medium of such a single resonator is arranged to form at least partly closed optical circle.  
     
     
         16 . The optical device according to  claim 14 , wherein said optical medium partly or completely consists of one of the following materials or of their combination: solid material, liquid material, gaseous material or vacuum.  
     
     
         17 . The optical device according to  claim 16 , wherein said solid material is dielectric material or semiconductor material.  
     
     
         18 . The optical device according to  claim 14 , wherein said optical resonator arrangement comprises at least one fiber or waveguide resonator.  
     
     
         19 . The optical device according to  claim 10 , wherein said polarization separating means is/are based on the use of one or more of the following optical items: Wollaston prism, Glan-Foucault polarizer, Nicol prism, Rochon prism, dielectric coating polarizer, wire grid polarizer, polymer based film polarizer, single polarization mode transmitting fiber or photonic crystal polarization separator.  
     
     
         20 . The optical device according to  claim 19 , wherein said polarization separating means is a polarization beam splitter or a polarization beam selector.  
     
     
         21 . The optical device according to  claim 10 , wherein said device further comprises means for altering the polarization state of the light in one or more of the following positions: before entering the resonator arrangement, within the resonator arrangement, after the resonator arrangement but before the polarization separating means, within the polarization separating means or after the polarization separating means.  
     
     
         22 . The optical device according to  claim 10 , wherein said device further comprises active light amplifying means.  
     
     
         23 . The optical device according to  claim 22 , wherein said active light amplifying means comprise a semiconductor optical amplifier.  
     
     
         24 . The optical device according to  claim 22 , wherein said active light amplifying means comprise a rare-earth doped waveguide.  
     
     
         25 . The optical device according to  claim 10 , wherein said device is partly or completely manufactured from miniaturized optical components.  
     
     
         26 . The optical device according to  claim 10 , wherein said device is partly or completely manufactured by use of light scattering periodic microstructures.