Pigtailed laser diodes have typical coupling efficiencies of 35% and 75% for singlemode and multimode fibers, respectively. Singlemode fiber output beam is circular with wavefront distortion better than 1/15 of a wave. Fiber ends are polished at an angle and positioned off-center with respect to lens axis to reduce backreflection into the laser-diode cavity. Typical backreflection is -45 dB. Laser diodes pigtailed with polarization-preserving fibers are also available.