INPLANE Photonics -

Planar Lightwave Circuits (PLCs):

Inplane is a leading practitioner of "glass on silicon" PLC technology. This technology supports complex and versatile photonic integration.

Standard versions of PLC technology are well documented, and have been practiced since the late 1980's. They combine significant features of optical fiber and integrated circuit technology. Basically, light-guiding channels, similar in function to optical fibers, are defined on a silicon platform. These are fabricated by depositing sequential glass layers onto silicon wafers. Typically, an intermediate "core" layer with an elevated refractive index is patterned using photolithography and dry-etching. This patterned structure becomes the light-guiding channel. This baseline technology is well suited to the fabrication of passive devices such as couplers and AWGs which depend on the proximity, controlled spacing and path lengths of parallel waveguides. The Silicon chip provides a robust support for the waveguides. Such PLC components are interfaced to fiber optic networks via edge attached fibers.

Inplane practices a much more advanced level of PLC technology, in terms of the number and variety of photonic elements, which are integrated on a single PLC chip. The PLC platform is extremely versatile and can support multiple technologies and functions through the monolithic and/or hybrid integration of sophisticated optical functions. Inplane has made breakthroughs in a number of key areas, which push the envelope for highly integrated Photonic circuitry and make such integrated products feasible. This includes;

The integration of Erbium Doped Waveguide Amplifiers (EDWAs) into PLC circuits. This in-line amplification removes loss-imposed barriers to high-level integration.
multi-delta waveguide circuits, which permit simultaneous optimization of critical parameters in a diverse group of devices. These waveguides are efficiently "spliced" using on-chip, low-loss mode transformers.
The hybrid integration of active elements including lasers and detectors on chip. With selective use of multi-delta waveguides, efficient coupling can be achieved to e.g. flip chip bonded active devices. The role of the silicon substrate is also expanded from a mere physical platform to an active thermal and electrical interconnect.

The deposition of metal interconnects and heaters further increase the range of achievable functionality to include thermo-optic Switches, VOAs and also RF transmission lines for analog signals.

The extensibility of the PLC platform is far from exhausted and Inplane envisions products which include;

MEMS integration, where chip-to-chip or monolithic integration can be employed. This is extremely interesting for wavelength insensitive, low-power, optical switches