Three-dimensional optical memory

Abstract

The present invention is directed to a three-dimensional memory apparatus for storing information in a volume comprising of an active medium. The active medium is capable of changing from a first to a second isomeric form as a response to radiation of a light beam having an energy substantially equal to a first threshold energy. The concentration ratio between a first and a second isomeric form in any given volume portion represents a data unit. The active medium in the memory apparatus comprises of diarylalkene derivatives, triene derivatives, polyene derivatives or a mixture thereof. The invention is further directed to means for reading the data units from the isomeric states of the active medium in different portions of said active medium where the two isomeric forms have a substantially different absorption coefficient for absorbing energy of a second threshold energy. Reading may also be carried out by measuring the scattering pattern of the two isomeric forms.

1 . A three-dimensional memory apparatus comprising an active medium, said active medium being capable of changing from a first to a second isomeric form in a multiphoton process; said memory apparatus being characterized in that said active medium comprises diarylalkene derivatives of formula (I): 
         Ar 1 C(R 1 )═C(R 2 )Ar 2   (I) 
       wherein R 1  and R 2  are not hydrogen and wherein Ar 1  and Ar 2  are optionally substituted aryl groups.  
     
     
         2 . A three-dimensional memory apparatus according to  claim 1 , wherein one of said first and second isomeric forms is a cis form and the other one is a trans form.  
     
     
         3 . A three-dimensional memory apparatus according to  claim 1  which is linearly transparent to interacting light.  
     
     
         4 . A three-dimensional memory apparatus according to  claim 1 , wherein R 1  and R 2  are electron acceptors selected from pyridinium and ammonium salts, alkenyl or alkynyl groups, azobenzenes, nitrites, halides, or nitro compounds and the substituents on the Ar 1  and Ar 2  are electron donors selected from alkyls, alkoxy groups, ethers and thioethers, alcohols, thiols and their salts, amines, biphenyls, and heteroaromatics.  
     
     
         5 . A three-dimensional memory apparatus according to  claim 4 , wherein the active medium is a compound of formula (II) or (III):  
       
         
           
           
               
               
           
         
       
       wherein n is 1 to 6.  
     
     
         6 . An optical data carrier comprising an active medium, said active medium being capable of changing from a first to a second isomeric form in a multiphoton process; said optical data carrier being characterized in that said active medium comprises diarylalkene derivatives.  
     
     
         7 . An optical data carrier according to  claim 6 , wherein one of said first and second isomeric forms is a cis form and the other one is a trans form.  
     
     
         8 . An optical data carrier according to  claim 6 , wherein said diarylalkene derivatives are of the general formula 
         Ar 1 C(R 1 )═C(R 2 )Ar 2   (I) 
       wherein R 1  and R 2  are not hydrogen and wherein Ar 1  and Ar 2  are optionally substituted aryl groups.  
     
     
         9 . An optical data carrier according to  claim 6 , wherein R 1  and R 2  are electron acceptors selected from pyridinium and ammonium salts, alkenyl or alkynyl groups, azobenzenes, nitrites, halides, or nitro compounds and the substituents on the Ar 1  and Ar 2  are electron donors selected from alkyls, alkoxy groups, ethers and thioethers, alcohols, thiols and their salts, amines, biphenyls, and heteroaromatics.  
     
     
         10 . An optical data carrier according to  claim 9  wherein the active medium is a compound of formula (II) or (III):  
       
         
           
           
               
               
           
         
       
       wherein n is 1 to 6.  
     
     
         11 . A memory apparatus according to  claim 1 , wherein said active medium is embedded in a supporting matrix.  
     
     
         12 . An optical data carrier according to  claim 6  wherein said active medium is embedded in a supporting matrix.  
     
     
         13 . A memory apparatus according to  claim 1 , wherein said active medium is chemically bound to a polymeric supporting matrix.  
     
     
         14 . An optical data carrier according to  claim 6  wherein said active medium is chemically bound to a polymeric supporting matrix.  
     
     
         15 . A method of producing a three-dimensional pattern of different response to multiphoton interaction 
 (a) providing a volume comprising an active medium, having diarylalkene derivatives and being capable of being in either a first or a second isomeric form, said medium being capable of changing from said first to said second isomeric form as a result of multiphoton absorption, and said first and second isomeric forms have mutually different response to multiphoton interaction;    (b) directing to selected portions of the active medium a light beam having only in said portion an intensity that activates multiphoton change of said active medium from the first to the second isomeric form, said selected portions having different X, Y, and Z coordinates;    thereby creating in said volume a three-dimensional pattern of different cross-sections to multiphoton fluorescence.    
     
     
         16 . A method of producing a three-dimensional pattern of different response to multiphoton interaction 
 (a) providing a volume comprising an active medium, having diarylalkene derivatives being capable of being in either a first or a second isomeric form, said medium being capable of changing from said first to said second isomeric form as a result of multiphoton absorption,    (b) transferring by nonlinear process to selected portions of the active medium a light energy having in said portion an energy threshold that activates change of said active medium from the first isomeric form, said selected portions having different X, Y, and Z coordinates.    
     
     
         17 . A method of identifying the isomeric form residue of an active medium in a portion of a three-dimensional pattern producible in a method according to  claim 15 , the method comprising directing to said portion of the pattern a light beam causing predominantly in said portion fluorescence, reading the intensity of the produced fluorescence, wherein said fluorescence being substantially different in intensity in one isomeric form than the other, and thereby identifying the isomeric form residue of the active medium in said portion.  
     
     
         18 . A method of identifying the isomeric form residue of an active medium comprising diarylalkenes in a portion of a three-dimensional pattern producible in a method according to  claim 15 , the method comprising directing to said portion of the pattern a light beam causing predominantly in said portion multiphoton interaction, and reading the intensity of the produced interaction.  
     
     
         19 . A method of identifying the isomeric form residue of an active medium in a portion of a three-dimensional pattern producible in a method according to  claim 16 , the method comprising directing to said portion of the pattern a light beam causing predominantly in said portion fluorescence, reading the intensity of the produced fluorescence, wherein said fluorescence being substantially different in intensity in one isomeric form than the other, and thereby identifying the isomeric form residue of the active medium in said portion.  
     
     
         20 . A method of identifying the isomeric form residue of an active medium comprising diarylalkenes in a portion of a three-dimensional pattern producible in a method according to  claim 16 , the method comprising directing to said portion of the pattern a light beam causing predominantly in said portion multiphoton interaction, and reading the intensity of the produced interaction.