Patent ID: 11909442
Assignee: RAYTHEON BBN TECHNOLOGIES CORP.
Field: Telecommunications (Electrical engineering)
Classification: CPC H  G | IPC G  H

Claim 0:
1. A photonic radio frequency (RF) In-phase (I) Quadrature-phase (Q) signal correlator comprising:
a photonic integrated circuit (PIC) comprising:
a first optical waveguide configured to receive a laser light signal from a continuous wave (CW) laser source modulated with a first radio frequency signal to form a first RF modulated optical signal S1(t), wherein t is time;
a first 1 to M optical splitter having an input coupled to the first optical waveguide and M outputs, the first 1 to M optical splitter configured to receive Si(t) at the input and divide the signal S1(t) to provide a signal S1′(t) at the M outputs to form M first RF modulated optical signals S1′(t), wherein each of the M first RF modulated optical signal signals S1′(t) have substantially equal power, wherein M is a positive integer greater than 1.

M discrete optical delay lines coupled to the M outputs of the first 1−to-M optical splitter, wherein the M discrete optical delay lines each provide a separate delay from 0×Δτ to (M−1) Δ96  respectively to provide M different delayed first RF modulated optical signals S1′(t), S1′(t−-Δτ), . . . S1′(t−(M−1) Δτ), where 1/Δτ is more than twice a bandwidth of the first RF signal;
a second optical waveguide configured to receive a laser light signal of the CW laser source modulated with a second radio frequency signal to form a second RF modulated optical signal S2(t);
a second 1-to-M optical splitter having an input coupled to the second optical waveguide and M outputs, the second 1to M optical splitter configured to receive the modulated optical signal S2(t) at the input and divide the signal S2(t) to provide a signal S2′(t) at the M outputs to form M second RF modulated optical signals, wherein each of the M second RF modulated optical signal signals S2′(t) have substantially equal power;
M I/Q photo receivers, wherein each I/Q photo receiver is configured to receive a different delayed first RF modulated optical signal S1′(M−1) Δτ) and a second RF modulated optical signal S2′(t) and output an in-phase (I) integrated correlated weight coefficient χreal(m) and a quadrature-phase (Q) integrated correlated weight coefficient χimag(m);

a processor electrically coupled to the first and second outputs of the M I/Q photo receivers, the processor configured to receive and sum the χreal(m) and χimag(m) according to the summation, ∑
    
     m
     =
     0
    
    
     M
     -
     1
    
   
   
    
     (
     
      
       
        χ
        
         τ
         ⁢
         e
         ⁢
         a
         ⁢
         l
        
       
       (
       m
       )
      
      +
      
       i
       ⁢
       
        
         χ
         
          i
          ⁢
          m
          ⁢
          a
          ⁢
          g
         
        
        (
        m
        )
       
      
     
     )
    
    ⁢
    
     exp
     ⁡
     (
     
      i
      ⁢
      2
      ⁢
      π
      ⁢
      m
      ⁢
      Δτ
      ⁢
      f
     
     )
    
   
  
  ,, to output a frequency domain correlated signal of the first RF signal and the second RF signal having real and imaginary parts.