69 research outputs found
Soliton Microcomb Range Measurement
Laser-based range measurement systems (LIDAR) are important in many
application areas including autonomous vehicles, robotics, manufacturing,
formation-flying of satellites, and basic science. Coherent laser ranging
systems using dual frequency combs provide an unprecedented combination of long
range, high precision and fast update rate. Here, dual-comb distance
measurement using chip-based soliton microcombs is demonstrated. Moreover, the
dual frequency combs are generated within a single microresonator as
counter-propating solitons using a single pump laser. Time-of-flight
measurement with 200 nm precision at 500 ms averaging time is demonstrated.
Also, the dual comb method extends the ambiguity distance to 26 km despite a
soliton spatial period of only 16 mm. This chip-based source is an important
step towards miniature dual-comb laser ranging systems that are suitable for
photonic integration
Gigahertz-repetition-rate soliton microcombs
Soliton microcombs with repetition rates as low as 1.86 GHz are demonstrated, thereby entering a regime more typical of table–top combs. Low rates are important in spectroscopy and relax requirements on comb processing electronics
Nonlinear Optics in Chip-based Microresonators and their Applications
Optical micro-resonators have been studied for decades as a platform to investigate optical physics, and to miniaturize bulky optical systems. In the last decade, optical frequency combs, which have revolutionized the precision measurement of time and frequency, have been demonstrated in optical micro-resonators via the combined effect of parametric oscillation and cascaded four-wave mixing. More recently, soliton mode-locking has made possible low-noise/reproducible generation of these miniature combs (microcombs). In this thesis, we demonstrated the generation of soliton microcombs from silica wedge disk micro-resonators and the characteristics of the soliton microcombs are described. We also applied soliton microcombs to dual-comb spectroscopy and distance measurement (LIDAR) for the first time. Also, ways to improve spectral resolution, signal-to-noise ratio, and spectral coverage are discussed. In addition to soliton microcombs, a novel spiral resonator is studied as a stable optical frequency reference. Combined with a frequency comb, this new type of chip-based reference cavity is also applied to generate stable microwaves via optical frequency division. Lastly, we generated a stimulated Brillouin laser (SBL) from the optical micro-resonator and its phonon-limited linewidth is studied. Application of the SBL for rotation measurement is also demonstrated. This thesis is organized into six chapters. Throughout the thesis, the implication and potential of my PhD work toward chip-based advanced optics system are discussed.</p
Microresonator Brillouin gyroscope
Optical-based rotation sensors have revolutionized precision, high-sensitivity inertial navigation systems. At the same time these sensors use bulky optical fiber spools or free-space resonators. A chip-based, micro-optical gyroscope is demonstrated that uses counterpropagating Brillouin lasers to measure rotation as a Sagnac-induced frequency shift. Preliminary work has demonstrated a rotation-rate measurement that surpasses prior micro-optical rotation-sensing systems by over 40-fold
Generation of high-stability solitons at microwave rates on a silicon chip
Because they coherently link radio/microwave-rate electrical signals with
optical-rate signals derived from lasers and atomic transitions, frequency
combs are having a remarkably broad impact on science and technology.
Integrating these systems on a photonic chip would revolutionize
instrumentation, time keeping, spectroscopy, navigation and potentially create
new mass-market applications. A key element of such a system-on-a-chip will be
a mode-locked comb that can be self-referenced. The recent demonstration of
soliton pulses from a microresonator has placed this goal within reach.
However, to provide the requisite link between microwave and optical rate
signals soliton generation must occur within the bandwidth of electronic
devices. So far this is possible in crytalline devices, but not chip-based
devices. Here, a monolithic comb that generates electronic-rate soliton pulses
is demonstrated.Comment: Xu Yi, Qi-Fan Yang, Ki Youl Yang contributed equally to this wor
Microresonator Soliton Dual-Comb Spectroscopy
Rapid characterization of optical and vibrational spectra with high
resolution can identify species in cluttered environments and is important for
assays and early alerts. In this regard, dual-comb spectroscopy has emerged as
a powerful approach to acquire nearly instantaneous Raman and optical spectra
with unprecedented resolution. Spectra are generated directly in the electrical
domain and avoid bulky mechanical spectrometers. Recently, a miniature
soliton-based comb has emerged that can potentially transfer the dual-comb
method to a chip platform. Unlike earlier microcombs, these new devices achieve
high-coherence, pulsed mode locking. They generate broad, reproducible spectral
envelopes, which is essential for dual-comb spectroscopy. Here, dual-comb
spectroscopy is demonstrated using these devices. This work shows the potential
for integrated, high signal-to-noise spectroscopy with fast acquisition rates.Comment: 7 pages, 4 figure
Directly pumped 10  GHz microcomb modules from low-power diode lasers
Soliton microcombs offer the prospect of advanced optical metrology and timing systems in compact form factors. In these applications, the pumping of microcombs directly from a semiconductor laser without amplification or triggering components is desirable to reduce system power and to simplify system design. At the same time, low-repetition-rate microcombs are required in many comb applications as an interface to detectors and electronics, but their increased mode volume makes them challenging to pump at low power. Here 10 GHz repetition rate soliton microcombs are directly pumped by low-power (<20  mW) diode lasers. High-Q silica microresonators are used for this low-power operation and are packaged into fiber-connectorized modules that feature temperature control for improved long-term frequency stability
Microresonator soliton dual-comb imaging
Fast-responding detector arrays are commonly used for imaging rapidly changing scenes. Besides array detectors, a single-pixel detector combined with a broadband optical spectrum can also be used for rapid imaging by mapping the spectrum into a spatial coordinate grid and then rapidly measuring the spectrum. Here, optical frequency combs generated from high-Q silica microresonators are used to implement this method. The microcomb is dispersed in two spatial dimensions to measure a test target. The target-encoded spectrum is then measured by multi-heterodyne beating with another microcomb having a slightly different repetition rate, enabling an imaging frame rate up to 200 kHz and fill rates as high as 48 megapixels/s. The system is used to monitor the flow of microparticles in a fluid cell. Microcombs in combination with a monolithic waveguide grating array imager could greatly magnify these results by combining the spatial parallelism of detector arrays with spectral parallelism of optics
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