Integrated optical device

An integrated optical device comprising a waveguide 16 can be tested by forming a recess 23 on the surface across the waveguide, and providing a discrete reflective device 22 insertable into the recess. It is preferred that the reflective device is a prism, insertable into the recess so as to reflect light leaving the waveguide. Suitable design of the prism permits the light to leave vertically if this is desired. The recess is preferably etched by any suitable etching process. It is preferred that the arrangement is employed for selective testing, in which the reflective device will be inserted into and out of the recess as desired or necessary. Accordingly, the reflective device can be supported on a moveable arm to allow its position to be controlled. This could be driven by servomechanical or piezoelectric means, or the like. A testing apparatus is also described, comprising a stage for an integrated optical device, a reflective device moveable towards the stage, and a light sensing device disposed to detect light reflected from the reflective device.