Balanced bypass circulators and folded universally-balanced interferometers

Abstract

The invention generally relates, in one aspect, to an interferometer system. The interferometer system includes a splitter/combiner element (SCE), a first bi-directional optical path, and a second bi-directional optical path.

1 - 22 . (canceled) 
     
     
         23 . A circulator bypass for use in an interferometer system, the circulator bypass comprising:
 a first bi-directional input/output port;   a second bi-directional input/output port;   a first optical circulator coupled to at least one of the first and second bi-directional input/output ports;   a first optical path extending from the first bi-directional input/output port to the second bi-directional input/output port, supporting substantial transmission efficiency of light at least one wavelength; and   a second optical path extending from the second bi-directional input/output port to the first bi-directional input/output port, supporting substantial transmission efficiency of light at least one wavelength,   wherein, the group delay in propagation of light through the first optical path is substantially equal to the group delay in propagation of light through the second optical path.   
     
     
         24 . The circulator bypass of  claim 23 , wherein the first optical path permits a substantial transmission of light from the first bi-directional input/output port to the second bi-directional input/output port over an operating wavelength range of the circulator bypass. 
     
     
         25 . The circulator bypass of  claim 23 , wherein the second optical path permits a substantial transmission of light from the second bi-directional input/output port to the first bi-directional input/output port over the operating wavelength range of the circulator bypass. 
     
     
         26 . The circulator bypass of  claim 23 , wherein the first and second optical paths are spatially separated in at least a part of the propagation path. 
     
     
         27 . The circulator bypass of  claim 23  further comprising at least one embedded optical device coupled to the first optical circulator. 
     
     
         28 . The circulator bypass of  claim 27 , wherein the embedded optical device comprises an optical delay line. 
     
     
         29 . The circulator bypass of  claim 28 , wherein the optical delay line is a length of optical waveguide. 
     
     
         30 . The circulator bypass of  claim 27 , wherein the embedded optical device comprises an optical signal processing device. 
     
     
         31 . The circulator bypass of  claim 30 , wherein the optical signal processing device is a filter. 
     
     
         32 . The circulator bypass of  claim 27 , wherein the embedded optical device comprises a phase shifter. 
     
     
         33 . The circulator bypass of  claim 23  further comprising a second optical circulator coupled to a different one of the first and second bi-directional input/output ports than the first optical circulator. 
     
     
         34 . The circulator bypass of  claim 33 , wherein each of the first and second optical circulators comprises first, second, and third ports, and further wherein the first port of the first optical circulator is coupled to the first bi-directional input/output port, the first port of the second optical circulator is coupled to the second bi-directional input/output port, the second port of the first optical circulator is coupled through a third optical path to the third port of the second optical circulator, and the third port of the first optical circulator is coupled through a fourth optical path to the second port of the second optical circulator. 
     
     
         35 . The circulator bypass of  claim 34 , wherein a phase shift spectrum accumulated due to propagation in the third optical path differs from a phase shift spectrum accumulated due to propagation in the fourth optical path by it radians plus an integer multiple of 2π radians over an operating wavelength range of the circulator bypass. 
     
     
         36 . The circulator bypass of  claim 34 , wherein at least one of the third and fourth optical paths comprises an embedded optical device. 
     
     
         37 . The circulator bypass of  claim 33 , wherein the first optical circulator and the second optical circulator are substantially identical physical structures. 
     
     
         38 - 53 . (canceled)