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Optical components

Xponent Cuts Packaging Xpenses

When it comes to optical components, what are the three most important things? Packaging, packaging, and packaging.

So says Xponent Photonics Inc., a startup out of California Institute of Technology (Caltech) that will unveil a new packaging technique at next week's OFC Conference.

Xponent's technology avoids the need for active alignment, a process by which optical sub-components are positioned to extremely tight tolerances by tweaking their position while also monitoring the output from the device. Active alignment is time-consuming, requires expensive machinery and skilled operators, and is generally blamed for hampering components vendors' efforts to ramp up to huge volumes quickly (see Packaging the Optical Future).

Mind you, huge volumes aren't exactly foremost in anyone's mind right now. Many startups that were providing automated manufacturing equipment and services have been forced to quit the market or alter their business plans (see KSaria Changes Faces). Indeed, one of the most prominent startups in this field, Axsun Technologies Inc., recently exited the contract manufacturing business, which once provided the majority of its revenues (see Axsun Gets $111 Million for Subsystems).

But Jeff Rittichier, Xponent's CEO, still sees an opportunity. "Today all the volumes are in the access market," he says. "And as core spending comes back, there's nothing that we're doing that can't be translated [into core components]."

Rittichier acknowledges that access, with its price sensitivity, is a tough market to compete in. Xponent is going to come up against fierce competition from companies such as Luminent Inc., which does all its manufacturing in the Far East, where labor costs are much lower than in the West.

So how does Xponent's technology stack up against the benefits of moving a conventional assembly operation to a place where labor costs a dollar a day? "Even if the labor cost [of overseas manufacturing] is zero, we can build the whole thing for less than the cost of the subcomponents in a conventional design," Rittichier boasts.

Xponent's secret is what it calls a "surface-mount converter", which takes light that's bouncing back and forth across a chip and couples it out of the top surface with virtually 100% efficiency, according to Rittichier. Surface-mount converters can be built into most existing active optical components, such as lasers, detectors, etc.

Getting light from the converter into fiber requires a second chip, which mates with the top surface of the converter. This second chip incorporates a waveguide to capture light coming out of the first chip, turning it from the vertical back to the horizontal. At the end of the waveguide is a v-groove, to which an optical fiber can be clipped.

This approach builds all the difficult, sub-micron alignments into the semiconductor chip itself, says Rittichier. The two remaining alignments -- matching the waveguide with the converter, and the fiber to the v-groove -- have more relaxed tolerances, and can be carried out using standard pick-and-place equipment.

"You go from an opto-bonder -- something costing millions of dollars with minutes of cycle time -- to a much less expensive semiconductor bonder, with only seconds of cycle time," Rittichier notes.

Surface-mount photonics, as Xponent likes to call it, also shares some of the benefits of Vertical Cavity Surface Emitting Lasers (VCSELs). Lasers and other devices can be tested on-chip, before the wafer is broken up into die, which allows dud devices to be winnowed out at an early stage of the manufacturing process. That adds to the cost savings.

However, we should point out Xponent is not actually making VCSELs, as Light Reading once surmised (see Xposing Xponent Photonics).

Caltech scientists provided the seeds of the technology, while Rittichier and several colleagues from former cable TV components maker Ortel (which was bought by Agere Systems [NYSE: AGR/A]), set the startup on its current course when they joined in October 2001. Xponent had changed its name three times up to that point; who knows how many times it had changed its product plans! Xponent plans to produce "catalogue components" under its own name, but it will also offer packaging services to other components vendors, by adapting their designs to take advantage of surface mount converter technology.

At OFC, the startup will show a triplexer -- a bidirectional transceiver for fiber-to-the-home (FTTH) applications, which receives data signals at 1480nm, video signals at 1550nm, and sends upstream signals at 1310nm. Several customers are evaluating the product, according to Rittichier.

But even with the right technology, the access market may be a tough one to crack. "No one really knows if that business is going to grow or not," commented Near Margalit, CEO of Luminent.

Xponent now has 40 full-time employees, including 13 from Caltech.

— Pauline Rigby, Senior Editor, Light Reading

dwdm2 12/5/2012 | 12:24:15 AM
re: Xponent Cuts Packaging Xpenses Vertical resonanace coupling is not a new idea, it has been around for a while. Apparently Xponent has added two additional interfaces to get to the fiber from the chip. For all practical purposes, this will contribute significantly to the "unreliability" of the device. I am curious how are they addressing this issue.

While surface mount route is cheaper, it is useful only in the mm regime. So the miniaturization will suffer as well. In other words it is still stuck with discrete/bulk technology.

Comments?

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"Xponent's secret is what it calls a "surface-mount converter", which takes light that's bouncing back and forth across a chip and couples it out of the top surface with virtually 100% efficiency, according to Rittichier. Surface-mount converters can be built into most existing active optical components, such as lasers, detectors, etc.

Getting light from the converter into fiber requires a second chip, which mates with the top surface of the converter. This second chip incorporates a waveguide to capture light coming out of the first chip, turning it from the vertical back to the horizontal. At the end of the waveguide is a v-groove, to which an optical fiber can be clipped."

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