Featured Engineer

Interview with Dr. Holger Schmidt

Dr. Holger Schmidt

Dr. Holger Schmidt, Professor of EE; Director, W.M. Keck Center for Nanoscale Optofluidics, UC Santa Cruz

How did you get into electronics/ engineering and when did you start?

My original degree is in physics. My M.S. thesis project dealt with semiconductor devices with direct applications in fiber-optic communications. After my PhD work in Electrical Engineering on a similar topic, I decided to develop new optical devices and methods with real-world applications.

What are your favorite hardware tools that you use?

I enjoy working with a variety of lasers, in particular ultrafast lasers that produce short optical pulses only about 100 femtoseconds long. With these lasers, we can study materials on time scales that can not be reached electronically. We also have recently set up a dual beam electron/ion beam microscope in our W.M. Keck Center for Nanoscale Optofluidics. An optofluidic device combines integrated optics with microfluidics. This can be a fluidically tuneable optical device, for example a fluidic dye laser in which the active laser dye solution is contained in a microchannel on a chip. It can also be a device that uses integrated optical elements (waveguides, filters, splitters) to investigate or manipulate particles in a microfluidic channel, for example an integrated biosensor.

This is an extremely versatile nanofabrication and nanocharacterization tool that is a lot of fun to work with and allows us to both sculpt and image objects on the nanoscale.

What are your favorite software tools that you use?

I mostly work with MATLAB, do some programming in C, and design optical waveguide structures using simulation packages from Photon Design.

What is on your bookshelf?

I have recently read “The Master Switch: The Rise and Fall of Information Empires “ by Tim Wu which deals with the fascinating story of the people and companies that invented new communication technologies and how they deal with issues of information control. “The elegant universe” by Brian Greene also tells a great story on the cosmic scale, presenting an introduction to string theory and its implications. I also read contemporary and classic fiction, plus a lot of children’s books with my family. Most recently, I read Aaron Hawkins’ “The year money grew on trees” which tells a great coming-of-age story that shows how hard work and persistence and a great group of friends can accomplish almost anything.

Do you have any tricks up your sleeve?

In my view, the keys to achieving breakthroughs in the lab are a combination of good planning ahead of time, persistence, the ability to recognize problems or new directions, and a bit of luck at the right time.

What has been your favorite project?

For a number of years, I have had the vision of realizing optical quantum interference effects on a chip. Quantum coherence produces strange effects such as making opaque materials transparent, slowing light down or making single photons “talk to each other”. Possible applications for quantum coherence devices include all-optical nonlinear devices (e.g. switches) that work on the few to single photon level, optical storage and memory, extremely sensitive metrology devices (magnetometers, interferometers…) or single photon light sources and detectors.

In collaboration with our colleagues at BYU, we have recently succeeded in slowing light down over a 1000 times on a tiny silicon chip. Viewed differently, we have taken a 20 foot long optical pulse and compressed it to a fraction of an inch on a chip.

Do you have any note-worthy engineering experiences?

Being exposed to a 1 million volt spark from a Tesla coil while standing in a metal suit that acted as a Faraday cage and NOT getting shocked was one of the most exhilarating experiences of my teaching career.

What are you currently working on?

We’re using laser optics in a number of ways. We are studying nanomagnets for next generation data storage media, will attempt to stop light on a chip to create optical memory devices, and are developing optofluidic chips for biomolecular diagnostics such as virus detection at the point of care.

We use different methods to make the magnets. We make our own magnets using electron beam lithography. A photoresist is patterned with nanoscale holes; magnetic material (e.g. Ni) is deposited, followed by a liftoff process. We also get samples from Western Digital, San Jose, formerly Hitachi Global Storage Technologies. These are metallic multilayers deposited on nanosize islands that were etched into a substrate wafer. Finally, we work with a group at the University of Chemnitz, Germany, who deposit magnetic layers on top of self-assembled silica nanospheres. The spheres produce ordered patterns as they are spread on a wafer which can make for a very quick and inexpensive patterning step. The main application we are interested in at the moment is bit-patterned magnetic storage media for next generation hard drives. However, nanomagnets are also relevant for memory devices (MRAM) or other emerging spintronic applications.

What direction do you see your business heading in the next few years?

I see a lot of potential in optofluidic technology – the combination of microfluidics and integrated optics. It allows us to look at devices that have been used for optoelectronic and communication applications in a new light. Their combination with non-solid media such as gases and liquids poses new research questions, but also has a lot of applications in the life sciences, biomedicine, toxicology, pollution monitoring and other fields.

What challenges do you foresee in our industry?

We need to stay one step ahead which will providing cutting-edge training to our bright and motivated students.

Visit Holger's EEWeb Profile
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