Moody & Co-PIs – Secure $1.15M for Advanced 3D Printing

From the Robert Mehrabian College of Engineering News article "Galan Moody, 4 Co-PIs Secure $1.15 Million for Advanced 3D Printing”

A new age of 3D printing is here, even though the initial technology for what is also known as additive manufacturing arrived less than twenty years ago. UC Santa Barbara is stepping into the era thanks to a $1.15 million grant from the National Science Foundation (NSF) to purchase the most cutting-edge 3D printing technology available: a 3D rapid nanoprinting system based on two-photon photolithography. The equipment will enhance the capabilities of the already widely recognized UCSB Nanofabrication Facility, (aka the “Nanofab” or “Nanotech”). 

“The unique capabilities of this system open the door to new approaches to nano- and micro-manufacturing of complex structures and devices that are no longer constrained by geometry nor confined to two-dimensional planes,” the authors write.

By securing the grant, lead PI Galan Moody, UCSB professor of electrical and computer engineering, and four co-PIs — Marley Dewey (Bioengineering), Andrew Jayich (Physics), Sumita Pennathur (Mechanical Engineering), and Andrea Young (Physics) — are ensuring that UCSB can take a leadership role in pushing the boundaries of what the new technology can do. Says Moody: “There are just a few universities in the U.S. that have tools with these capabilities.”

The tools are needed, the proposal reads, “because we are at the limit of what can be achieved with existing nanofabrication tools, which have enabled wafer-scale fabrication of semiconductors, dielectrics, and metals with resolution down to approximately ten nanometers [nm], but only in a planar [essentially two-dimensional] geometry. Additional complex, time-consuming steps are required to create increasingly essential 3D microstructures.”

Advances in the past couple of years have brought 3D printing to the realm of the very small, supporting an array of applications by enabling on-chip 3D printing of microstructures, a capacity that will benefit researchers in many disciplines.

Moody provides an example to illustrate a limitation of the first 3D printing technology. “Normally,” he says, “you start with a semiconductor wafer [typically silicon] and use photolithography to yield a semiconductor with a pattern that has been transferred to it. If you look top down, it's just a 2D pattern. There is depth to it, but it's more like a thin film that’s maybe a few hundred nanometers thick, so you can’t raster-scan it in all three dimensions to make a nice 3D structure. Ten-nm-resolution lithography is available at off-campus commercial foundries, but none is capable of creating complex 3D structures with nanoscale resolution and high speed for high-throughput prototyping, which are required for next-generation devices. Being able to make structures in true three dimensions opens new capabilities.”

What Makes the New Tech New

While both the original and the new processes of 3D printing share a name, the earliest technology was actually more of a two-dimensional framework, Moody explains. “Three-dimensional objects could be created, but only by aggregating (the ‘additive’ part of “additive manufacturing,” as the first generation of 3D printing was also called) very thin layers of materials, which had length and width but no real depth.
 
Quantum networks, secure quantum communications, quantum sensors, and optical quantum computers and simulators require high-quality sources of entangled photon pairs, and much research is devoted to improving source quality, especially the pair-generation rate (PGR) which is the number of photon pairs extracted from the chip per second. The proposal explains that, Optical extraction efficiency from integrated chips to fiber is limited by the diameters of the various modes, which, typically, differ from each other by ten to fifty percent for quantum networking. To get around that discrepancy and “get the light into the fiber,” Moody says, “we bring the fiber right to the edge of the chip to capture it before it can diverge.”

The new system makes it possible to print a tiny polymer lens fewer than fifty micrometers wide onto the edge of a chip, enabling it to guide the optical mode. Fig. 3, Panel B shows an optical fiber and a small 3D-printed cone on the end of it that also acts as a lens to focus the light so that it goes into and propagates down the fiber rather than scattering as “loss,” a big problem in photonics.The lens can be printed either on the edge of a chip or on a fiber, as long as the light coming out of the chip is “matched to collect into the fiber,” Moody says.

“We try to arrange the components such that the light doesn’t “see” the fiber as a discontinuity. That allows the light beam coming out of the photonic chip to couple nicely into the fiber and keep going, resulting in very low loss,” Moody adds. “That's really hard to do, because there is often a mismatch between the shape of the optical beam in our small wave guide and how it looks in the much-larger fiber. To make the transition requires a smooth 3D structure without any jagged edges, which can trap or scatter the light, resulting in loss.

Smooth nanoscale 3D printing is essential for many structures and devices being made at UCSB. The new 3D printing technology can deliver it.

RMCOE News — "Galan Moody, 4 Co-PIs Secure $1.15 Million for Advanced 3D Printing"