Vertical-cavity surface-emitting lasers (VCSELs) are semiconductor lasers that emit light outward in a beam parallel to the surface of the chip. They are widely used in telecommunications, optical data storage, sensing, and printing applications. VCSELs are available in a variety of wavelengths and offer good collimation and efficiency. One of their primary advantages is that they require very little current (on the order of microwatts) to operate, making them more power-efficient than edge-emitting lasers. They are also simpler to manufacture than edge-emitting lasers, which require a complicated optical alignment process. Finally, VCSELs are very reliable, with lifetime estimated at many thousands of hours.