Scientists Create First Chip-Scale Ultrafast Laser After 20-Year Quest
EPFL researchers achieve breakthrough that could miniaturize powerful femtosecond laser technology for medical diagnostics and atomic clocks.
Researchers at the École Polytechnique Fédérale de Lausanne (EPFL) have achieved a long-sought breakthrough in integrated photonics, creating the first chip-scale ultrafast laser capable of matching the performance of traditional tabletop femtosecond systems. The innovation, published in Nature, delivers pulse energies of 1.05 nanojoules and pulse durations as short as 147 femtoseconds, all contained within a compact photonic chip.
For more than two decades, creating a high-pulse-energy femtosecond laser on a chip was considered the "holy grail" of integrated photonics, according to Professor Tobias J. Kippenberg, who led the research team. Traditional ultrafast lasers have remained large, expensive systems occupying entire optical tables, despite their critical importance in applications ranging from precision manufacturing and eye surgery to optical frequency combs that power the world's most accurate atomic clocks.
The breakthrough relies on an overlooked laser architecture called the Mamyshev oscillator, which places a nonlinear waveguide between two optical filters that transmit different portions of the light spectrum. As intense laser pulses travel through the waveguide, they expand into broader color ranges, with part of the broadened pulse passing through both filters to continue circulating. Weaker light cannot broaden sufficiently and gets blocked by the filters, creating a self-selecting mechanism for maintaining strong pulses.
The design proves particularly well-suited for photonic chips because it doesn't require components that are difficult to manufacture on silicon nitride platforms. Co-author Zheru Qiu explained that photonic chips naturally confine light to extremely small waveguides, causing strong light-matter interactions that can destabilize many laser architectures. However, the Mamyshev oscillator shows remarkable resistance to these nonlinear effects that typically plague integrated devices.
This advancement could dramatically reduce the size and cost of ultrafast laser systems while making them more accessible for widespread applications. The technology promises to enable new possibilities in medical diagnostics, quantum computing, and precision measurement, where femtosecond-scale timing precision is crucial. The research team believes their elegant architecture will inspire further innovations in integrated photonics and help bring laboratory-grade laser performance to portable, chip-based devices.