editor's blog
Subscribe Now

An Optical MEMS Reference Process

A while back Micralyne announced a MEMS reference process. There are a few of these running around: attempts to achieve – or at least grasp at – a standard process that can address a wide range of MEMS devices.

Most of Micralyne’s processes are confidential, per their customer relationships, in typical MEMS style. What they did here was to take a “neutral” improved version of what they do well and open it up. They’re not sure that customers will simply line up and use that process in high-volume production outright, but at the very least it’s a conversation starter and a way for them to show their capabilities without divulging secrets.

Micralyne’s strength is primarily optical MEMS: mirrors and comb drives and such. Those feature large in their process, but, in order to be a bit more general, they added some inertial devices, like a 2-axis (but not a 3-axis) accelerometer and a gyro, as well as some biomedical devices.

It’s a two-wafer process (plus handles); cavities are etched into the base wafer and the top wafer; the top wafer is inverted and fusion-bonded to the bottom wafer, after which the top-wafer handle is removed. From the top, release is performed and then metal is laid down. This metal step pertains in particularly to giving mirrors a nice reflective surface.

As a complete aside, in the discussion of their optical capabilities, there was repeated mention of “hitless” functionality with respect to the mirrors. I actually had a hard time finding out what this meant, and a conversation with Micralyne helped clarify. For any of you who are, like me, not steeped in optical, this is a way of changing optical routing in an optical switch without interfering with other channels.

It’s actually a pretty simple concept. Below I show a scenario with various fibers being routed to various other fibers via the gold mirrors. In particular, fiber 3 routes to fiber 1 (moving bottom to top). Let’s say we want to reroute that so that fiber 3 now routes to fiber 6. If we just move the mirror across, then the light stream from fiber three will interfere with all of the other receiving channels as it scans across (which I’ve tried to illustrate on the right, with the stars indicating interference as the beam moves; at the particular moment shown, it’s made it as far as target fiber 4 on its way to 6).

Hitless_switching_1.png

So the hitless idea is that you simple tilt the mirror in the orthogonal direction first so that it’s no longer targeting the receiving fibers. You can then sweep it across to the new target; the light is now moving under the other beams and doesn’t interfere. Once over in the new position, you then bring the beam back up to its normal working position and the connection is made (with no disturbance to the others).

Hitless_switching_2.png

You can find more info in their release and whitepapers.

Leave a Reply

featured blogs
Apr 18, 2019
China is hugely important for electronics in general and semiconductor in particular. You can't really appreciate it from the bubble of Silicon Valley, you have to go there. For the second year,... [[ Click on the title to access the full blog on the Cadence Community s...
Apr 18, 2019
Thermal Shock testing isn’t unique to the connector world, but it does play a big role in the qualification testing that Samtec puts all connectors through before they are released for production. Chances are likely that you thermally shock many items per day and don...
Apr 17, 2019
Release season has once again arrived in the Electronic Board Systems division. Xpedition VX.2.5 is now available for download from Support Center. Along with updates to the general design environment, this download includes a new version of Xpedition AMS. Interested in learn...
Jan 25, 2019
Let'€™s face it: We'€™re addicted to SRAM. It'€™s big, it'€™s power-hungry, but it'€™s fast. And no matter how much we complain about it, we still use it. Because we don'€™t have anything better in the mainstream yet. We'€™ve looked at attempts to improve conven...