1 $\times$ 2 Wavelength Multiplexer With High Transmittances Using Extraneous Self-Imaging Phenomenon

This paper introduces a wavelength multiplexer (MUX) using the extraneous self-imaging (Ex_SI) phenomenon, which is not mentioned in multimode-interference theory. The Ex_SI phenomenon in silica-based multimode waveguides was experimentally studied. Then, using data for the Ex_SI phenomenon, the wavelength MUX for the wavelengths of 1310 and 1550 nm was developed. The optimum length of the multimode waveguide, with a width of 18 mum, was confirmed as a 3670- mum wavelength MUX. For the wavelengths of 1310 and 1550 nm, the excess losses were determined to be -0.4 and -0.45 dB, respectively, while the extinction ratios were 16.9 and 19.7 dB, respectively