Silicon is efficient for electronics and versatile for integration, while being very inefficient in generating or detecting light in the telecom wavelength window. Consequently, Silicon Photonics integrated circuits must be designed to be easily integrated with lasers fabricated from Indium Phosphide, detectors based on germanium doped silicon, or other functions and materials through Hybrid Photonic Integration. NeoPhotonics designs Silicon Photonics modulators, receivers, coherent optical subassemblies and laser subassemblies and fabricate the Silicon wafers in commercial Silicon foundries. We co-packages these Silicon Photonics chips with lasers made from Indium Phosphide to form Active Silicon elements.
A prime example of NeoPhotonics Silicon Photonics Technology is its coherent optical subassembly, or COSA, which consists of a polarization multiplexed quadrature modulator, four driver amplifiers, and an intra-dyne coherent receiver which has four pairs of balanced photo-diodes and four trans-impedance amplifiers. The COSA enables our 400ZR coherent transceiver in OSFP or DD-QSFP form factors for <120km DCI, and 400ZR+ for metro applications.
A second form of Silicon based PIC is based on doped silica glasses are formed with controllable indices of refraction and are used to make waveguide circuits called Planar Lightwave Circuits or PLCs. NeoPhotonics has been shipping PLC based PICs for almost 20 years. Due to the very low loss, complex optical circuits are possible using silica waveguides. Typical devices are Passive Splitters, Arrayed Waveguide Gratings for DWDM MUX/DMUX, Variable Optical Attenuators, and Optical Switches. For example, an 8×16 Multi-Cast Switch combines eight 1×8 splitters and sixteen 1×8 switches plus numerous taps, crossings, and other element on a single chip. PLC wafers are manufactured in NeoPhotonics specialized wafer fab.