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Applied Optics Lab creates novel on-chip laser source useful for biodetection

Santa Cruz, CA—A team led by Holger Schmidt, professor of electrical and computer engineering and Narinder Kapany Chair of Optoelectronics at the University of California, Santa Cruz have demonstrated a new on-chip laser and its integration into optofluidic chips. 

“This novel tunable light source can add another functional component to our optofluidic bioanalysis chips,” Schmidt said, “adding both flexibility and simplicity and moving us closer to a fully integrated lab on a chip.

The results will be published in Optics Letters.

“The project was led by two graduate students,” Schmidt said. “Jennifer Black (Ph.D. electrical engineering ’18) who is now on an NRC Fellowship at the National Institute of Standards and Technology, and Ph.D. student Tyler Sano.” 

They built a laser source made of a corrugated sidewall structure that is integrated into a microfluidic channel to form a distributed feedback (DFB) laser using rhodamine 6G dissolved in an ethylene glycol and water solution. Lasing is demonstrated with a threshold pump power of 87.9 microwatts. Laser threshold and output power were optimized with respect to rhodamine 6G concentration and core index and found to be in good agreement with a rate equation model. Additionally, the laser can be switched on and off mechanically using a pneumatic cell inducing positive pressure on the grating.

The idea is to incorporate a tunable light source onto a biodetection chip, a significant step toward creating a complete “laboratory on a chip.” This technology would be particularly valuable as a potential platform for creating a rapid, point-of-care diagnostic system capable of detecting viruses such as Zika and SARS-CoV-2. 

For more information about Holger Schmidt’s Applied Optics lab, please visit: https://photon.soe.ucsc.edu/