Researchers at the University of California in Santa Barbara have produced 1.55-µm vertical-cavity surface-emitting lasers (VCSELs) for telecommunications applications as a single crystal by molecular beam epitaxy. The process is more reliable and less expensive than wafer fusion, which assembles long-wavelength VCSELs from layers that are grown on different wafers. Team leader Larry Coldren, director of the Optoelectronics Technology Center at the university, determined that indium phosphide, rather than the more common gallium arsenide, offers a better lattice constant for the antimony-containing layers of the devices. The researchers deposited the layers on a 2-in. substrate of indium phosphide and isolated the active regions by etching to yield 25,000 VCSELs per wafer.