Shanhui Fan, Postdoctoral Faculty Sponsor
Self-Injection Locked Frequency Conversion Laser
LASER & PHOTONICS REVIEWS
View details for DOI 10.1002/lpor.202200663
View details for Web of Science ID 000928844600001
Self-regulating soliton switching waves in microresonators
PHYSICAL REVIEW A
2022; 106 (5)
View details for DOI 10.1103/PhysRevA.106.053508
View details for Web of Science ID 000898385000006
Integrated Pockels laser
2022; 13 (1): 5344
The development of integrated semiconductor lasers has miniaturized traditional bulky laser systems, enabling a wide range of photonic applications. A progression from pure III-V based lasers to III-V/external cavity structures has harnessed low-loss waveguides in different material systems, leading to significant improvements in laser coherence and stability. Despite these successes, however, key functions remain absent. In this work, we address a critical missing function by integrating the Pockels effect into a semiconductor laser. Using a hybrid integrated III-V/Lithium Niobate structure, we demonstrate several essential capabilities that have not existed in previous integrated lasers. These include a record-high frequency modulation speed of 2 exahertz/s (2.0 × 1018 Hz/s) and fast switching at 50 MHz, both of which are made possible by integration of the electro-optic effect. Moreover, the device co-lases at infrared and visible frequencies via the second-harmonic frequency conversion process, the first such integrated multi-color laser. Combined with its narrow linewidth and wide tunability, this new type of integrated laser holds promise for many applications including LiDAR, microwave photonics, atomic physics, and AR/VR.
View details for DOI 10.1038/s41467-022-33101-6
View details for Web of Science ID 000853182100016
View details for PubMedID 36097269
View details for PubMedCentralID PMC9467990
Probing material absorption and optical nonlinearity of integrated photonic materials
2022; 13 (1): 3323
Optical microresonators with high quality (Q) factors are essential to a wide range of integrated photonic devices. Steady efforts have been directed towards increasing microresonator Q factors across a variety of platforms. With success in reducing microfabrication process-related optical loss as a limitation of Q, the ultimate attainable Q, as determined solely by the constituent microresonator material absorption, has come into focus. Here, we report measurements of the material-limited Q factors in several photonic material platforms. High-Q microresonators are fabricated from thin films of SiO2, Si3N4, Al0.2Ga0.8As, and Ta2O5. By using cavity-enhanced photothermal spectroscopy, the material-limited Q is determined. The method simultaneously measures the Kerr nonlinearity in each material and reveals how material nonlinearity and ultimate Q vary in a complementary fashion across photonic materials. Besides guiding microresonator design and material development in four material platforms, the results help establish performance limits in future photonic integrated systems.
View details for DOI 10.1038/s41467-022-30966-5
View details for Web of Science ID 000809423400063
View details for PubMedID 35680923
View details for PubMedCentralID PMC9184588
Vernier spectrometer using counterpropagating soliton microcombs
2019; 363 (6430): 965-+
View details for DOI 10.1126/science.aaw2317
View details for Web of Science ID 000460194200042
Vernier spectrometer using counterpropagating soliton microcombs.
Science (New York, N.Y.)
Determination of laser frequency with high resolution under continuous and abrupt tuning conditions is important for sensing, spectroscopy, and communications. We show that a single microresonator provides rapid and broadband measurement of optical frequencies with a relative frequency precision comparable to that of conventional dual-frequency comb systems. Dual-locked counterpropagating solitons having slightly different repetition rates were used to implement a vernier spectrometer, which enabled characterization of laser tuning rates as high as 10 terahertz per second, broadly step-tuned lasers, multiline laser spectra, and molecular absorption lines. Besides providing a considerable technical simplification through the dual-locked solitons and enhanced capability for measurement of arbitrarily tuned sources, our results reveal possibilities for chip-scale spectrometers that exceed the performance of tabletop grating and interferometer-based devices.
View details for PubMedID 30792361