A new measurement method of propagation loss of self-written polymer waveguides using mirror reflection

Light-induced self-written (LISW) optical waveguide is advantageous to connect optical fiber with the waveguide. We investigated a new measurement method of propagation loss of the LISW optical waveguides, where branching mirror structure is introduced. Usually the cut-back method for measuring propagation loss of waveguides is applied, though it requires repeating processes; cutting, polishing, and measuring. Because of these time consuming processes, simple process to measure the optical loss of the LISW optical waveguide is required. We made LISW waveguide containing 2 to 4 partly reflecting mirrors, and measured the optical power of reflected light. The propagation loss (1.1±0.3[dB/cm]) that was calculated from the reflected optical power agrees well with the value measured using the cut-back method (1.1±0.2[dB/cm]). The measurement time of the new method reduced to about one fourth than that by the cut-back method.