Techniques are described for time-of-fly sensors with hybrid refractive gradient-index optics. Some embodiments are for integration into portable electronic devices with cameras, such as smart phones. For example, a time-of-fly (TOF) imaging subsystem can receive optical information along an optical path at an imaging plane. A hybrid lens can be coupled with the TOF imaging subsystem and disposed in the optical path so that the imaging plane is substantially at a focal plane of the hybrid lens. The hybrid lens can include a less-than-quarter-pitch gradient index (GRIN) lens portion, and a refractive lens portion with a convex optical interface. The portions of the hybrid lens, together, produce a combined focal length that defines the focal plane. The hybrid lens is designed so that the combined focal length is less than a quarter-pitch focal length of the GRIN lens portion and has less spherical aberration than either lens portion.