In recent years, silicon photonics has emerged as an enabling technology for a large number of high capacity intra- and inter-data center optical interconnections (DCI), as well as for telecom optical networks. Powered by one or more Indium Phosphide-based lasers, a silicon photonics integrated circuit (PIC) is typically composed of one or more channels of waveguides together with optical modulators and receivers. These devices are generally fabricated in commercial foundries using large size silicon wafers with diameters of 8” or 12”, thereby ensuring in mass production that the cost in high volumes of each individual silicon photonics chip is reasonably low. Moreover, many innovative low-cost on-wafer testing and packaging techniques have been developed to make Silicon PICs into a true high volume and cost-effective solution for both direct- and coherent-detection optical fiber systems.
To illustrate this capability, today a silicon PIC for coherent detection systems used in communications is packaged in a 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. This COSA can be optically connected to a laser subassembly and electrically connected to a coherent digital signal processor (DSP) semiconductor chip. The COSA, a laser subassembly, and a coherent DSP in combination comprise a complete high speed coherent transceiver.
This is just one example of a general capability. In a similar manner a silicon photonics modulator array can be co-packaged with an indium phosphide laser source to make Active Silicon™ for short reach transceivers for intra-data center interconnections.
NeoPhotonics has productized silicon photonic COSA operating at 400Gb/s per wavelength and has been conducting advanced research on aCOSA for 800G and above. This capability enables us to make our 400ZR coherent transceiver in OSFP or DD-QSFP form factors for <120km DCI, and 400ZR+ for metro applications.
NeoPhotonics COSA is based on NeoPhotonics photonic integration technology and is approximatively the same size as our products like HB-CDM or Micro-ICR, and so cuts the component footprint in half while simplifying fiber management and board layout. The small form factor is required for integration inside compact pluggable transceiver modules such as OSFP and QSFP-DD. The COSA also achieves high bandwidth suitable for 64 Gbaud applications.
NeoPhotonics is also a pioneer of very low-loss silicon planar lightwave circuits (PLC), which are ideal for switching, filtering or interferometric applications. We design and manufacture PLC in our own fabs and integrate them with other photonic circuits using Advanced Hybrid Photonic Integration. The promise of silicon photonics for optical integration is a triumph as more optical functionalities are demonstrated at increasingly higher levels of performance and at lower cost. Further, by using silicon-on-insulator waveguides, beam-splitters, modulators, and silicon compound photodetectors, both the footprint and the cost of complex integrated devices can be dramatically reduced. However, indium phosphide lasers have remained separate to date.
NeoPhotonics further offers a range of lasers that specifically support the needs of on-chip silicon photonics components. These solutions provide high power, close optical coupling and optimization for strict power consumption and heat dissipation. These Active Silicon™ solutions extend the potential range accessible for future silicon photonics innovations.
Benefits of Silicon Photonics