Manufacturing Bits: July 7

Silicon photonics prototyping; molecules in 3D; terahertz spectroscopy.


Silicon photonics prototyping
A group of European and other research organizations have put the finishing touches on a project to help propel the development of silicon photonics into the commercial market.

The project, dubbed ESSenTIAL, enables small- to mid-sized enterprises to develop prototypes and products based on silicon photonics. Funded by the European Commission, the project includes Imec, CEA-LETI, Tyndall Institute, VTT, IHP, TNO and CMC.

The goal of the project is to develop advanced multi-project-wafer services as well as packaging services for silicon photonics. It is also aimed to expand the services of ePIXfab, which is developing a fabless silicon photonics ecosystem. This organization also provides multi-project wafer services.

Multi-project wafer for photonic IC prototyping (Source: ePIXfab)

Multi-project wafer for photonic IC prototyping (Source: ePIXfab)

Within the ESSenTIAL project, the portfolio of silicon photonics services offered by ePIXfab has been extended. High speed active devices up to 25 Gbit/s were added to the offering.

Another achievement of the project is the creation of silicon photonics packaging services at Tyndall Institute. “Packaging is often seen as the Achilles heel of photonic component technology. Tyndall Institute has developed a family of solutions, encompassing optical, electrical and RF packaging. These standardized packaging approaches for silicon photonic chips are available to industry through the ePIXfab alliance,” said Peter O’Brien, head of the Photonics Packaging Group at Tyndall.

Molecules in 3D
JILA–a partnership of the National Institute of Standards and Technology (NIST) and the University of Colorado–have devised a microscope instrument that can measure the three-dimensional movement of individual molecules over many hours.

The instrument was originally designed to track biological cells down to the smallest bits of DNA. But over time, the instrument could be used in other applications, such as nanotechnology.

Typically, a microscope can be used to look at DNA and other biological structures, but it’s difficult to examine specimens with any degree of stability. But JILA’s measurement platform can look at structures at a tenth of a nanometer for up to 100 seconds at a time. Researchers from JILA have even operated its system for up to 28 hours straight. The instrument can detect motion over a wide range of time scales.

JILA's microscopy technique tracks tiny objects (Source: NIST)

JILA’s microscopy technique tracks tiny objects (Source: NIST)

JILA’s technology is based on a two lasers. The lasers measure the positions of opposite ends of a molecule, based on the intensity of scattered light. The scattered light is detected by a photodiode. The signals are digitized, analyzed and used to calculate the positions of the samples.

The technology can be applied to optical trapping techniques, atomic force microscopes and super-resolution imaging.
“This technology can actively stabilize two items relative to each other with a precision well below one nanometer at room temperature,” said JILA/NIST physicist Tom Perkins, on the agency’s Web site. “This level of 3D stability may start to interest the nanomanufacturing world, when they look at making and characterizing things on the single-nanometer scale.”

Terahertz spectroscopy
The Max Planck Institute for Polymer Research, Johannes Gutenberg University (JGU) and others have devised a new and fast way to measure the building blocks of current and future magnetic memories.

Researchers have developed a technology called ultrafast terahertz spectroscopy. A terahertz is one thousand billion oscillations per second.

Today’s hard drives can store information using nanoscale magnetic sensors. MRAMs, MEMS and other products are based on a similar concept.

The operation of magnetic sensors, dubbed spin-valves, is based on the so-called giant magnetoresistance (GMR) effect. The GMR effect is a change in the electrical resistance. It’s based on the concept of electrical conduction in ferromagnetic metals.

In addition, Mott spin-dependent conductivity is at the heart of magnetic memories. But the direct observation, and measurement, of Mott spin-dependent conductivity has been a challenge.

It requires magneto-transport measurements in the sub-100 fs regime. Researchers from Max Planck and others have managed to break the speed barrier for fundamental magneto-transport measurements using terahertz spectroscopy.

Difference in conduction by electrons with opposite spins in ferromagnetic metals can be resolved using terahertz imaging. (Source: Max Planck)

Difference in conduction by electrons with opposite spins in ferromagnetic metals can be resolved using terahertz imaging. (Source: Max Planck)

“By studying the interaction of THz electromagnetic waves – which oscillate about as fast as the electrons in metal scatter their momentum – with a spin-valve, we could directly measure for the first time the fundamental parameters of Mott conduction,” said Dmitry Turchinovich, project leader at Max Planck, on the organization’s Web site. “In particular, we found that the traditional measurements performed on the slower timescales significantly underestimate the spin-asymmetry in electron scattering which is responsible for the magnetic sensor operation”.

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