Experimental study on thermal memory effect in plastic optical fibers

A “thermal memory effect” of plastic optical fibers (POFs), with which the thermally induced loss is spontaneously recorded to POFs themselves, is experimentally investigated. We measure optical time-domain reflectometry traces of POFs under three conditions: (1) before heating a section of the POF, (2) shortly after heating the section, and (3) after cooling the section to room temperature. The loss becomes almost constant after heating for more than 200 s and no longer returns to initial value even after we cool the heated section to room temperature. The results show that the thermal memory effect has a potential of developing low-cost excess-heat detecting system in future.