Integrated optical devices include various configurations of active optical switches and other passive components such as splitters that are useful for controlling signals in optical data transmission networks. An optical switch may be used to switch light between waveguides on different substrates. The active optical switch may include one or more microfluidic droplets that are controllably movable relative to the coupling region to change the amount of light couplable between the first and second switch waveguides. Different configurations of the droplets can be controlled for operating the switch in different switching states. An optical switch can be included in an end use transceiver device for remotely controlling an optical time domain measurement. A microfluidic switch can be used to control wavelength-selective reflection in a waveguide reflector.