Scientists greatly expand the frequencies generated by a miniature optical ruler

Phys.org  February 23, 2022 A team of researchers in the US (NIST, University of Maryland) has produced a microcomb using two lasers, each generating a different frequency of light, instead of just one. They found that through a complex series of interactions with the soliton light circulating in the microring resonator, the second laser induced two new sets of teeth, or evenly spaced frequencies, that are replicas of the original set of teeth but shifted to higher and lower frequencies. The lower frequency set lies in the infrared part of the spectrum, while the other is at much high frequencies, […]

New tech builds ultralow-loss integrated photonic circuits

Phys.org  April 16, 2021 Researchers in Switzerland have developed a new technology for building silicon nitride integrated photonic circuits with record low optical losses and small footprints. They used Damascene process to make integrated circuits of optical losses of only 1 dB/m. Such low loss significantly reduces the power budget for building chip-scale optical frequency combs (“microcombs”), used in applications like coherent optical transceivers, low-noise microwave synthesizers, LiDAR, neuromorphic computing, and even optical atomic clocks. The team used the new technology to develop meter-long waveguides on 5×5 mm2 chips and high-quality-factor microresonators. They also report high fabrication yield, which is […]

Trapping light without back reflections

Phys.org  January 4, 2021 Due to material imperfections, some amount of light is reflected backwards in microresonators which disturbs their function. To reduce the unwanted backscattering an international team of researchers (UK, Germany) used the principle of noise cancelling headphone and introduced out-of-phase light to cancel out optical interference. To generate the out-of-phase light, the researchers position a sharp metal tip close to the microresonator surface. The tip also causes light to scatter backwards. As the phase of the reflected light can be chosen by controlling the position of the tip, backscattered light’s phase can be set so it annihilates […]