Optimal design conditions of adiabatic directional couplers of sin-square function based on Taguhi's method

Optimal design conditions of adiabatic directional couplers (ADC) of sin-square function (SSF) based on Taguchi's method is investigated with the consideration of interaction effects between design parameters. The validity of approximation theory of adiabatic directional couplers becomes questionable when the coupling length is not enough long so the beam propagation method is used. L₉ experimental tests based on Taguchi's method are performed, and beam propagation method is used to simulate design conditions. The objective of the work includes in the new design of adiabatic directional full couplers can obtain respectively low crosstalk and short couplers. The results indicated that the BMP simulate is the most important design parameter affecting the low crosstalk and short couplers of the sin-square function. For the SSF cases, we try and find the best sets of coupling waveguide structure parameters of adiabatic directional couplers with larger structure tolerance and shorter coupler length, the results can obtain 95% of the trust ranges. The optimal design conditions determined by Taguchi's method for reducing the low crosstalk and short couplers were verified experimentally in this work.