Broadband and Temperature Tolerant Silicon Nitride Liquid Controlled Waveguide Coupler

A broadband and temperature tolerant liquid-controlled adiabatic waveguide coupler (LCC) is realized. The LCC with silicon nitride waveguides is designed to be compatible with liquids that can be actuated by an electrowetting-on-dielectric system. This proof-of-principle demonstration with manual actuation paves the way toward the realization of non-voloptical switch systems. A 630-
${\mu }$
m-long LCC configured as a
$1\times 2$
switch has a measured insertion loss less than 1.5 dB and a crosstalk less than
$-14$
 dB for both bar and cross state over the telecommunication wavelength range 1260 to 1630 nm. Furthermore, the LCC is tolerant to variations in temperature. The measured excess insertion loss over the temperature range 21 to 73 
$^\circ$
C is less than 0.3 dB for bar and cross state, over the same wavelength range.