OneChip Photonics Inc. - Definitions & Glossary of Terms

A passive optical network (PON) is a point-to-multipoint, fiber-to-the-premises network architecture in which unpowered optical splitters are used to enable a single optical fiber to serve multiple premises, typically 32-128. A PON consists of an Optical Line Terminal (OLT) at the service provider's central office and a number of Optical Network Units (ONUs) near or at end-users. A PON configuration reduces the amount of fiber and central office equipment required, compared with point-to-point architectures.

Ethernet PON (EPON) is an Institute of Electrical and Electronics Engineers (IEEE) standard for using Ethernet for packet data. EPON uses standard 802.3 Ethernet frames with symmetric 1.25 gigabit per second (1.25 Gb/s) upstream and downstream rates.

Gigabit PON (GPON) is an International Telecommunication Union (ITU) standard for using larger, variable-length packets. GPON supports 2.5 gigabits per second (2.5 Gb/s) of downstream bandwidth and 1.24 gigabits per second (1.24 Gb/s) of upstream bandwidth.

Both the IEEE and the ITU are working on EPON and GPON standards that would support 10 gigabit per second (10 Gb/s) transmission rates.

Optical transceivers – which transmit and receive data using optical fiber rather than electrical wire – are the most critical components of Optical Network Units (ONUs). These transceivers include Diplexers, which transmit and receive on the same fiber, and Triplexers, which add an analog video overlay.

Triplexers split the optical signal into three separate wavelengths for transmitting and receiving voice, data and video:

If an ONU supports IPTV only and not RF (analog) video, then it only needs a diplexer. That is because the video stream is packetized as regular data transmitted over the 1490 nanometer wavelength, thus making the 1550 nanometer wavelength unnecessary. Diplexers generally cost less than triplexers.

PX-10 transceivers are used for links up to 10 kilometers (10 km), and PX-20 transceivers are used for links up to 20 kilometers (20 km).

Planar Lightwave Circuits (PLCs)

Optical waveguide circuitry fabricated by means of planar technology
Only passive optical devices made from transparent materials
Silica-on-silicon, polymers, silicon-on-isolator

Photonic Integrated Circuits (PICs)

Optical waveguides and waveguide devices fabricated by using semiconductor wafer processing technologies
Both passive and active photonic devices, transparent and opaque materials
Indium Phosphide (InP) and related III-V semiconductors

Optoelectronic Integrated Circuits (OEICs)

Photonic and electronic devices combined onto one chip fabricated by means of semiconductor wafer processing technologies
Passive and active photonic devices, together with electronic components
III-V semiconductors (InP or GaAs based), silicon (CMOS, SOI)

Carriers want ONUs to be small and inexpensive. Transceivers comprise a large percentage of an ONU's size and cost. Consequently, system vendors are always asking their component providers for smaller and cheaper transceivers. That is where OneChip comes in.

OneChip uses a new PIC design/fabrication approach, which is based on a vertical integration of all the active and passive components into a common multi-guide structure grown in one epitaxial step.

This approach is inherently high-yielding and low-cost. Further, OneChip's PIC-based transceivers can be manufactured using industry standard, automated assembly processes and machines.

OneChip's approach contrasts with multiple epitaxial growth step techniques, in which unneeded epitaxial material from the previous growth step(s) is selectively etched out and replaced with a required material in the following growth step(s). Such techniques may work well for high-end Wave Division Multiplexing (WDM) applications, but they are unsuitable for the fabrication yield/cost requirements of ONT transceivers.