Harvard University's breakthrough integrated on-chip laser makes it easy for chips to achieve industrial-grade applications
Physicists at Harvard University have developed a powerful new on-chip laser that emits bright pulses in the mid-infrared spectrum—an elusive but extremely useful range of light that can be used to detect gases and enable new spectroscopic tools. The device packs the functionality of a larger system into a tiny chip, without the need for any external components. It fuses a breakthrough photonic design with quantum cascade laser technology and is expected to soon revolutionize environmental monitoring and medical diagnostics by detecting thousands of light frequencies at once. Physicists at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have developed a compact laser that emits bright, ultrashort pulses of light in the mid-infrared spectrum—a wavelength range that is both scientifically valuable and technologically challenging. The device's performance is comparable to that of much larger photonic systems, but is fully integrated on a single chip. The research, published today (April 16) in the journal Nature, marks the first demonstration of an on-chip picosecond mid-infrared laser pulse generator that operates without any external components. The laser can generate optical frequency combs—a spectrum of evenly spaced frequencies—for a wide range of applications in high-precision measurements. This compact platform is expected to help realize a new generation of broad-spectrum gas sensors for environmental monitoring and advanced spectral tools for medical imaging. The fields of photonics and electromagnetics are undergoing profound changes brought about by the deep integration of numerical simulation technology. Traditional optical design and analysis methods are gradually showing their limitations when faced with problems such as complex light field control and prediction of optical properties of multi-scale structures. As a powerful numerical simulation tool, the FDTD method is accelerating its penetration into all aspects of optical and multidisciplinary cross-disciplinary research. From metasurface design to nano-optical structure analysis, from beam manipulation to photonic device optimization, FDTD is reshaping the paradigm of optical research and application. In terms of international trends, the study of metasurfaces has become a hot topic. Metasurfaces can break through the control capabilities of traditional optical components on light and realize flexible control of light in multiple dimensions such as phase, polarization, and amplitude. From basic research to practical applications, the potential of metasurfaces is constantly being explored, and new research results are emerging in an endless stream. For example, metasurfaces can be used to achieve precise control of the shape of light beams and generate special beams such as vortex beams and Airy beams. These beams have unique advantages and broad application prospects in the fields of optical communications, optical imaging, optical tweezers, etc. At the same time, the cross-integration of metasurfaces with cutting-edge disciplines such as nanophotonics and plasmonics has promoted the innovative development of the field of optics and provided new ideas and methods for solving some problems that are difficult to overcome with traditional optics. At the national demand level, my country's rapid development in the fields of optical communications, optical information processing, optical imaging, photonic chips, etc. has created an increasingly urgent need for talents who can master advanced optical design and simulation technologies. The "14th Five-Year Plan for the Development of the National Natural Science Foundation" clearly proposes in the priority development areas to "develop circuits, RF modules and antenna technologies with new materials, new architectures and new mechanisms, explore efficient electromagnetic computing, intelligent electromagnetic wave control methods, and leapfrog development of new technologies for electronic information systems to serve the national electronic information industry development strategy."