Embodiments of the present disclosure are directed toward techniques and configurations for a single mode optical coupler device. In some embodiments, the device may include a multi-stage optical taper to convert light from a first mode field diameter to a second mode field diameter larger than the first mode field diameter, and a mirror formed in a dielectric layer under an approximately 45 degree angle with respect to a plane of the dielectric layer to reflect light from the multi-stage optical taper substantially perpendicularly to propagate the light in a single mode fashion. Other embodiments may be described and/or claimed.