New coupler technology could assist in enabling tomorrow's silicon photonics

May 1, 2008, Pine Brook, NJ--Chiral Photonics has announced an advancement in using tapered coupler instead of lensing for low-loss integration of disparate photonic devices.

May 1st, 2008

May 1, 2008, Pine Brook, NJ--Silicon photonics, considered by many to be the future of computing and a host of other new applications also built around high-refractive-index contrast structures, can now be more efficiently connected to mainstay low-index contrast fiber, thanks to a breakthrough by Chiral Photonics scientists.

In a recently issued patent, Chiral Photonics researchers describe the photonics behind their tapered coupler (TC) device, the Helica TC, which consists of two concentric cores and a cladding. While the two cores have low-index contrast, the outer core and the cladding have high contrast. At input, the low-index contrast cores facilitate low-loss connectivity to standard fibers. The fiber then tapers down over its length, eliminating the inner core by the output end. At the output end, high-index contrast enables low-loss connectivity to high-index contrast structures such as planar waveguides.

This interconnect exploits a dual-core fiber design to allow light from a conventional low-numerical-aperture fiber to be efficiently endface-coupled into another waveguide with smaller mode field dimensions and higher numerical aperture. By permitting index-matching compounds to be used between the coupler and waveguide and eliminating the need for microlens-based coupling and air gaps, the Helica TC affords uniquely low loss and system stable integration. The technology supports both polarizing and polarization maintaining coupler variations.

High-index contrast structures within photonic integrated circuits (PICs) or planar lightwave circuits (PLCs) form the basis for a large fraction of the recent worldwide innovation in integrated optics. Via highly efficient lasers, extremely sensitive sensors, and waveguides moving vast amounts of data through small radius bends, these faster, smaller, and power-conserving PICs and PLCs promise to advance everything from consumer electronics to personal computing. PICs and PLCs stand to bring more sensitive and less invasive biomedical diagnostics, feed ever more information to wireless devices, and refine industrial processes from drug development to navigation systems.

"We believe this is a significant enabling technology for planar nanophotonics and in the field of high-index contrast photonics more generally," said Victor Kopp, Chiral Photonics' director of R&D. "In addition to the endface and evanescent coupling devices we are currently supplying, we plan to use this technology to introduce a passive alignment solution for board-to-board and chip-to-chip interconnects."

Chiral Photonics patented the Helica TC in December 2007. Developers of next-generation optoelectronics already employ it to couple standard fiber to planar waveguide devices and photonic nanostructures, as well as in other research. According to Gary Weiner, VP marketing and sales, this week's Helica TC announcement was timed to follow launch of the company's revised website on April 24.

More information on Chiral Photonics can be found on the company's web site:

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