is spliced to a connecting fiber 280 and embedded in the annulus of the flexible riser 200 may be a side hole polarimetric fiber sensor that creates birefringence and provides measurement resolution of less than about 0 01 psi pounds per square inch in one or more embodiments other types of fiber optic sensors 270 may be used such as those using a fiber bragg grating as described in yamate t ramos r t schroeder r j udd e u201c thermally insensitive pressure measurements up to 300 c using fiber bragg gratings written onto side hole single mode fiber u201d 14th international conference on optical fiber sensors ofs u2014 venice italy 11 13 oct 2000 the entire contents of which is incorporated herein by reference in one or more embodiments the phenomena known as u201c pressure induced birefringence u201d may be used to measure the pressure that a u201c side hole u201d fiber experiences a side hole fiber is a section of an optical fiber having two holes offset from the center of the fiber and running along the length of the sensing element the principle is described in detail in clowes j r and zervas m n u201c pressure sensitivity of side hole optical fibre sensors u201d ieee photonics technology letters vol 10 no 6 june 1998 and in clowes j r mcinnes j zervas m n and payne d n u201c effects of high temperature and pressure on silica optical fibre sensors u201d 12th international conference on optical fibre sensors 1997 osa technical digest series vol 16 optical society of america both of which are incorporated.