Optical components

Can Translume Direct-Write Success?

Startup Translume (no Website) plans to make optical components by burning patterns into a glass block with a high-power pulsed laser -- a method known as "direct-writing."

The company hasn't yet said what products it intends to manufacture, but it's likely that these will include passive components like splitters, attenuators, and arrayed waveguide gratings (AWGs). In that respect it's following in the footsteps of other integrated optics vendors like Bookham Technology PLC (Nasdaq: BKHM; London: BHM), Kymata Ltd., Lightwave Microsystems Corp., and NTT Electronics Corp. (NEL) (to name but a few). Translume was founded just a few weeks ago, so it's very early days. So far it has a bunch of ideas, four employees, and the support of Ardesta LLC, an investor cum incubator. The technology it's planning to use was developed at Clark MXR Inc. and the University of Michigan. Here's how direct-writing works. If an ultra-fast, high-power pulse from a laser is tightly focused below the surface of a glass block or wafer, then the glass melts. Each pulse melts a sphere of about 10 microns in diameter inside the glass.

The laser beam is scanned over the surface of the glass, tracing out each component, one at a time. It leaves a channel of molten material behind, which cools to form a waveguide.

The glass at the edge of the channel cools first to form low-density glass with a low refractive index. This process increases the pressure on the molten glass in the center of the channel, which then cools to form high-density, high-refractive-index glass.

Phillipe Bado, Translume's chief science officer, claims that laser-writing of optical components has three big advantages. One, it's cheap: "It's a simple technology that doesn't require a large clean-room production facility, so the cost of production should be significantly lower."

Two, the yield is high. "We're shooting for yields above 90 percent," he says. Although most component manufacturers don't like to admit it, yields in the low tens of percent are common for devices like AWGs, he adds. A high yield helps cut costs, too.

The third advantage is unique. The laser-writing process creates waveguides that have a circular cross-section rather than the usual rectangular one. As a result, it's possible to couple light from the waveguide into an optical fiber more easily.

Critics of the process say that direct-write methods, which "draw" components one at a time, are slow compared to parallel techniques, like photolithography. But Bado says this is a fallacy. "We believe we can get throughputs as high as anyone can get using parallel fabrication methods." That's mainly because optical circuits typically measure millimeters or even centimeters across, so not many of them fit on a wafer. "In optics, the advantages of writing in parallel are simply not as great as they are in microelectronics," Bado contends.

— Pauline Rigby, Senior Editor, Light Reading, http://www.lightreading.com

COMMENTS Add Comment
microfab 12/4/2012 | 8:26:01 PM
re: Can Translume Direct-Write Success? Clark-MXR, Inc. Board of Directors

Mr. William Clark, Ph.D.
Chairman of the Board
Clark-MXR, Inc.

Mr. Philippe Bado, Ph.D. <<<<<<<<<<<<<<
Vice-Chairman of the Board
Clark-MXR, Inc.

Mr. William G. May
Chairman and Founder, Burleigh Instruments, Inc.

Mr. Gerard Mourou, Ph.D. <<<<<<<<<<<<<<
Director, Center for Ultrafast Optical Sciences University of Michigan

Mr. Richard Snyder
President, Avalon Investments LLC

microfab 12/4/2012 | 8:26:01 PM
re: Can Translume Direct-Write Success? Hi Y'all. The story on Translume not having a web site is not exactly true ! Go to ClarkMXR or something like that ( a laser micromachining hardware firm for Ti Sapphire lasers ) and Dr. Philipe Bado is listed as an employee, and the technology of waveguide writing in glass by teraherz laser pulses for index gradient formation by glass compaction is fully described ( in what they call an online book ).

Stealth NOT !

The technique apparently uses two photon mixing from 2 lasers, so abitrary waveguide geometries can be made - including 3D helices and spirals. Speed of waveguide writing seems to be "competitive" ( can't define that yet ).

Can they acheive sufficient guide fabrication precision to acheive competitive and reproducible AWG fabrication to required tolerances, losses, channel separation and yield ! Possibly, but it remains to be demonstrated in a commercial grade volume production AWG. For certain the devices will be stable, and mode control will be circular ( ie limited PDL ).

But manufacturability will be determined by stage accuracy ( and tooling accuracy ) and laser pointing stability. All doable, but remains to be seen if they have the required tolerances engineered for volume production device reproducibility ( and therefore YIELD ).

Else this is very interesting, novel, patented technique and they just have to give it a real try in manufacturing to see if customers will bite for volume at prices they can do profitably.

Stay tuned for this one, as the story will be interesting.

regards, Microfab
Pauline Rigby 12/4/2012 | 8:25:59 PM
re: Can Translume Direct-Write Success? Thanks for pointing this out. Though I knew that the CSO Philippe Bado hailed from Clarke-MXR, I didn't realise the connection was quite so strong.

Read Clark-MXR's micromachining handbook at http://www.clark-mxr.com/micro....

The chapter about waveguides is at http://www.clark-mxr.com/micro....

[email protected]

microfab 12/4/2012 | 8:25:53 PM
re: Can Translume Direct-Write Success? It is a pleasure. Anytime. This stuff is so interesting I just have to use google to track things down. I had to do the search on Philipe Bado and found a BMDO grant which listed Clarke MXR and that unravelled it all.

best regards, microfab
laserfocus 12/4/2012 | 8:25:51 PM
re: Can Translume Direct-Write Success? the links are all down now, hmmmmm>?
Any idea why they would have pulled all of them?
microfab 12/4/2012 | 8:25:42 PM
re: Can Translume Direct-Write Success? they are back up now it seems with a clenaer web site interface.
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