With BIFROST, David Weld uses laser light in an ultracold atomic physics experiment his laboratory. / Photo by Tony Mastres

If you’re familiar with Norse mythology or have seen Marvel’s Thor movies, you might know the Bifrost, a magic rainbow bridge connecting Asgard, the world of the gods, to Earth.

While not as mythical as the bridge, UC Santa Barbara’s own recently acquired BIFROST, or Broadly-tunable Illumination Facility for Research, Outreach, Scholarship, and Training, parallels in its multispectral and connective character.

BIFROST is a titanium:sapphire laser with frequency doubling and sum frequency generation modules, distributed by a network of optical fibers to ten research and teaching laboratories in Broida Hall, which contains UCSB’s Department of Physics.

“The idea is that it’s like a faucet for laser light. A unique web interface including a ‘dial-a-wavelength’ feature will allow researchers in any of the laboratories to log on to the instrument, select a desired wavelength or tuning range, and simply begin their work,” said David Weld, an assistant professor of physics who led the efforts to bring BIFROST to campus.

The system is capable of producing spectroscopy-grade laser light at wavelengths from 350 nanometers to 1,000 nanometers, a range which spans nearly all visible colors and the near-infrared.

“Precise and powerful light sources are a critical enabling technology for research directions including atom and ion trapping, terahertz science, the study of solid-state defects, single-molecule biophysics, molecular spectroscopy, and cavity quantum electrodynamics. BIFROST should open up new possibilities for research in all these areas at UCSB,” Weld said.

David Weld shows part of BIFROST to UCSB Physics students and alumni. / Courtesy of David Weld

In addition, he said that undergraduate students can profit from access to the unique apparatus, which enhances their education through new experimental possibilities for upper-division laboratory classes such as optical spectroscopy, microscopy, and quantum optics with fluorescent defects in solid-state materials.

“As a side benefit, the fiber infrastructure installed as part of BIFROST constitutes a sort of ‘optical circulatory system’ for Broida Hall,” Weld said. “By plugging the BIFROST fibers into each other, it will be possible to connect any two of the fiber-equipped rooms to each other with a continuous single-mode fiber link. This will significantly expand future research collaboration possibilities.”

The Army Research Office and U.S. Department of Defense’s instrumentation grant program supported the installation of BIFROST at UCSB, due to its status as a minority-serving institution. With one of the largest physics bachelor’s programs in the United States, UCSB welcomes the $600,000 instrument’s timely arrival.

Weld said, “As a top-ten physics department in a minority-serving institution, the UCSB physics department is in a unique position to positively impact the training of the next generation of researchers.”

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