A compact integrated 1310/1550nm Y-branch waveguide wavelength demultiplexing coupler based on multimode interference is demonstrated. Theoretical analysis and simulation results for the demultiplexer configuration are presented. The structure performance can be optimized with an appropriate choice of some structural parameters such as input and output waveguide widths, refractive index profiles and coupler length. The contrasts achieve 9.8 and 9.4dB for a graded-index Y-branch wavelength demultiplexer at 1310 and 1550nm, and the corresponding insertion losses are 0.60 and 0.73dB at 1310 and 1550nm, respectively. For a step-index Y-branch wavelength demultiplexer, contrasts are 7.6 and 7.5dB, and insertion losses are 0.75 and 0.83dB at 1310 and 1550nm, respectively.
Theoretic characteristics of Er3+-Yb3+ co-doped phosphate glass waveguide amplifier are studied by resolving rate-propagation equations with overlapping integral method. Considering the effect of the up-conversion and ASE, the amplifier gain and ASE spectrum are obtained. The relations between the amplifier gain and several parameters are analyzed, such as the waveguide length, pump power, up-conversion coefficient, propagation loss and so on. The experiment result agrees well with the numerical result.