scholarly journals Towards integrated photonic interposers for processing octave-spanning microresonator frequency combs

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Ashutosh Rao ◽  
Gregory Moille ◽  
Xiyuan Lu ◽  
Daron A. Westly ◽  
Davide Sacchetto ◽  
...  
Keyword(s):  
Silicon Nitride ◽  
Form Factors ◽  
System Level ◽  
Optical Systems ◽  
Optical Frequency ◽  
Frequency Combs ◽  
Restricted Form ◽  
Future System ◽  
On Chip ◽  
The Individual

AbstractMicrocombs—optical frequency combs generated in microresonators—have advanced tremendously in the past decade, and are advantageous for applications in frequency metrology, navigation, spectroscopy, telecommunications, and microwave photonics. Crucially, microcombs promise fully integrated miniaturized optical systems with unprecedented reductions in cost, size, weight, and power. However, the use of bulk free-space and fiber-optic components to process microcombs has restricted form factors to the table-top. Taking microcomb-based optical frequency synthesis around 1550 nm as our target application, here, we address this challenge by proposing an integrated photonics interposer architecture to replace discrete components by collecting, routing, and interfacing octave-wide microcomb-based optical signals between photonic chiplets and heterogeneously integrated devices. Experimentally, we confirm the requisite performance of the individual passive elements of the proposed interposer—octave-wide dichroics, multimode interferometers, and tunable ring filters, and implement the octave-spanning spectral filtering of a microcomb, central to the interposer, using silicon nitride photonics. Moreover, we show that the thick silicon nitride needed for bright dissipative Kerr soliton generation can be integrated with the comparatively thin silicon nitride interposer layer through octave-bandwidth adiabatic evanescent coupling, indicating a path towards future system-level consolidation. Finally, we numerically confirm the feasibility of operating the proposed interposer synthesizer as a fully assembled system. Our interposer architecture addresses the immediate need for on-chip microcomb processing to successfully miniaturize microcomb systems and can be readily adapted to other metrology-grade applications based on optical atomic clocks and high-precision navigation and spectroscopy.

Machine learning regression approach to on-chip optical frequency combs analyses

2021 ◽  
Vol 60 (12) ◽  
Author(s):  
Jin Wen ◽  
Weijun Qin ◽  
Wei Sun ◽  
Chenyao He ◽  
Keyu Xiong ◽  
...  
Keyword(s):  
Machine Learning ◽  
Optical Frequency ◽  
Optical Frequency Combs ◽  
Frequency Combs ◽  
Regression Approach ◽  
On Chip

scholarly journals Generation of tunable, high repetition rate optical frequency combs using on-chip silicon modulators

2018 ◽  
Vol 26 (8) ◽  
pp. 10744 ◽  
Author(s):  
K. P. Nagarjun ◽  
Vadivukarassi Jeyaselvan ◽  
Shankar Kumar Selvaraja ◽  
V. R. Supradeepa
Keyword(s):  
Repetition Rate ◽  
High Repetition Rate ◽  
Optical Frequency ◽  
Optical Frequency Combs ◽  
Frequency Combs ◽  
High Repetition ◽  
On Chip

scholarly journals Noise Measurement and Reduction in Mode-Locked Lasers: Fundamentals for Low-Noise Optical Frequency Combs

2021 ◽  
Vol 11 (16) ◽  
pp. 7650
Author(s):  
Haochen Tian ◽  
Youjian Song ◽  
Minglie Hu
Keyword(s):  
Theoretical Models ◽  
Building Blocks ◽  
Low Noise ◽  
Noise Measurement ◽  
Optical Systems ◽  
Optical Frequency ◽  
Development Mode ◽  
Optical Frequency Combs ◽  
Frequency Combs ◽  
Mode Locked Lasers

After five decades of development, mode-locked lasers have become significant building blocks for many optical systems in scientific research, industry, and biomedicine. Advances in noise measurement and reduction are motivated for both shedding new light on the fundamentals of realizing ultra-low-noise optical frequency combs and their extension to potential applications for standards, metrology, clock comparison, and so on. In this review, the theoretical models of noise in mode-locked lasers are first described. Then, the recent techniques for timing jitter, carrier-envelope phase noise, and comb-line noise measurement and their stabilization are summarized. Finally, the potential of the discussed technology to be fulfilled in novel optical frequency combs, such as electro-optic (EO) modulated combs, microcombs, and quantum cascade laser (QCL) combs, is envisioned.

scholarly journals From the Lugiato–Lefever equation to microresonator-based soliton Kerr frequency combs

2018 ◽  
Vol 376 (2135) ◽  
pp. 20180113 ◽  
Author(s):  
L. A. Lugiato ◽  
F. Prati ◽  
M. L. Gorodetsky ◽  
T. J. Kippenberg
Keyword(s):  
Pattern Formation ◽  
Continuous Wave ◽  
Laser Frequency ◽  
Dissipative Structures ◽  
Low Noise ◽  
Optical Systems ◽  
Frequency Synthesis ◽  
Frequency Combs ◽  
Optical Microresonators ◽  
On Chip

The model, that is usually called the Lugiato–Lefever equation (LLE), was introduced in 1987 with the aim of providing a paradigm for dissipative structure and pattern formation in nonlinear optics. This model, describing a driven, detuned and damped nonlinear Schroedinger equation, gives rise to dissipative spatial and temporal solitons. Recently, the rather idealized conditions, assumed in the LLE, have materialized in the form of continuous wave driven optical microresonators, with the discovery of temporal dissipative Kerr solitons (DKS). These experiments have revealed that the LLE is a perfect and exact description of Kerr frequency combs—first observed in 2007, i.e. 20 years after the original formulation of the LLE—and in particular describe soliton states. Observed to spontaneously form in Kerr frequency combs in crystalline microresonators in 2013, such DKS are preferred state of operation, offering coherent and broadband optical frequency combs, whose bandwidth can be extended exploiting soliton-induced broadening phenomena. Combined with the ability to miniaturize and integrate on-chip, microresonator-based soliton Kerr frequency combs have already found applications in self-referenced frequency combs, dual-comb spectroscopy, frequency synthesis, low noise microwave generation, laser frequency ranging, and astrophysical spectrometer calibration, and have the potential to make comb technology ubiquitous. As such, pattern formation in driven, dissipative nonlinear optical systems is becoming the central Physics of soliton micro-comb technology. This article is part of the theme issue ‘Dissipative structures in matter out of equilibrium: from chemistry, photonics and biology (part 2)’.

Fabrication of Monolithic Integrated Bimaterial Resonant Uncooled IR Sensor

2013 ◽  
Vol 543 ◽  
pp. 176-179 ◽  
Author(s):  
D.Q. Zhao ◽  
Xia Zhang ◽  
P. Liu ◽  
F. Yang ◽  
C. Lin ◽  
...  
Keyword(s):  
Silicon Nitride ◽  
Hole Mobility ◽  
Micro Electro Mechanical System ◽  
Cmos Process ◽  
Standard Cmos Process ◽  
Ir Sensor ◽  
Cantilever Structure ◽  
Cmos Mems ◽  
On Chip ◽  
Micro Cantilever

In this work we studied the fabrication of a monolithic bimaterial micro-cantilever resonant IR sensor with on-chip drive circuits. The effects of high temperature process and stress induced performance degradation were investigated. The post-CMOS MEMS (micro electro mechanical system) fabrication process of this IR sensor is the focus of this paper, starting from theoretical analysis and simulation, and then moving to experimental verification. The capacitive cantilever structure was fabricated by surface micromachining method, and drive circuits were prepared by standard CMOS process. While the stress introduced by MEMS films, such as the tensile silicon nitride which works as a contact etch stopper layer for MOSFETs and releasing stop layer for the MEMS structure, increases the electron mobility of NMOS, PMOS hole mobility decreases. Moreover, the NMOS threshold voltage (Vth) shifts, and transconductance (Gm) degrades. An additional step of selective removing silicon nitride capping layer and polysilicon layer upon IC area were inserted into the standard CMOS process to lower the stress in MOSFET channel regions. Selective removing silicon nitride and polysilicon before annealing can void 77% Vth shift and 86% Gm loss.

scholarly journals System models for resilience in gerontology: application to the COVID-19 pandemic

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Katarzyna Klasa ◽  
Stephanie Galaitsi ◽  
Andrew Wister ◽  
Igor Linkov
Keyword(s):  
The Elderly ◽  
System Level ◽  
Improve Quality ◽  
Care Needs ◽  
Individual Level ◽  
Chronic Stressors ◽  
The World ◽  
Aging Adults ◽  
The Individual

AbstractThe care needs for aging adults are increasing burdens on health systems around the world. Efforts minimizing risk to improve quality of life and aging have proven moderately successful, but acute shocks and chronic stressors to an individual’s systemic physical and cognitive functions may accelerate their inevitable degradations. A framework for resilience to the challenges associated with aging is required to complement on-going risk reduction policies, programs and interventions. Studies measuring resilience among the elderly at the individual level have not produced a standard methodology. Moreover, resilience measurements need to incorporate external structural and system-level factors that determine the resources that adults can access while recovering from aging-related adversities. We use the National Academies of Science conceptualization of resilience for natural disasters to frame resilience for aging adults. This enables development of a generalized theory of resilience for different individual and structural contexts and populations, including a specific application to the COVID-19 pandemic.

scholarly journals Spectral Broadening in a Continuously Pumped Singly Resonant Second-Harmonic Cavity

2021 ◽  
Vol 11 (15) ◽  
pp. 7122
Author(s):  
Simona Mosca ◽  
Tobias Hansson ◽  
Maria Parisi
Keyword(s):  
Continuous Wave ◽  
Frequency Comb ◽  
Second Harmonic ◽  
Input Power ◽  
Second Order ◽  
Optical Frequency ◽  
Frequency Combs ◽  
Research Areas ◽  
Mixed Regime ◽  
Wide Range

Optical frequency comb synthesizers with a wide spectral range are an essential tool for many research areas such as spectroscopy, precision metrology, optical communication, and sensing. Recent studies have demonstrated the direct generation of frequency combs, via second-order processes, that are centered on two different spectral regions separated by an octave. Here, we present the capability of optical quadratic frequency combs for broad-bandwidth spectral emission in unexplored regimes. We consider comb formation under phase-matched conditions in a continuous-wave pumped singly resonant second-harmonic cavity, with large intracavity power and control of the detuning over several cavity line widths. The spectral analysis reveals quite distinctive sidebands that arise far away from the pump, singularly or in a mixed regime together with narrowband frequency combs. Notably, by increasing the input power, the optical frequency lines evolve into widely spaced frequency clusters, and at maximum power, they appear in a wavelength range spanning up to 100 nm. The obtained results demonstrate the power of second-order nonlinearities for direct comb production within a wide range of pump wavelengths.

scholarly journals Roadmap of Terahertz Imaging 2021

Sensors ◽  
2021 ◽  
Vol 21 (12) ◽  
pp. 4092
Author(s):  
Gintaras Valušis ◽  
Alvydas Lisauskas ◽  
Hui Yuan ◽  
Wojciech Knap ◽  
Hartmut G. Roskos
Keyword(s):  
Room Temperature ◽  
Continuous Wave ◽  
Computational Imaging ◽  
Imaging Systems ◽  
Thz Imaging ◽  
Operational Conditions ◽  
Frequency Combs ◽  
Wave Imaging ◽  
On Chip ◽  
Nano Imaging

In this roadmap article, we have focused on the most recent advances in terahertz (THz) imaging with particular attention paid to the optimization and miniaturization of the THz imaging systems. Such systems entail enhanced functionality, reduced power consumption, and increased convenience, thus being geared toward the implementation of THz imaging systems in real operational conditions. The article will touch upon the advanced solid-state-based THz imaging systems, including room temperature THz sensors and arrays, as well as their on-chip integration with diffractive THz optical components. We will cover the current-state of compact room temperature THz emission sources, both optolectronic and electrically driven; particular emphasis is attributed to the beam-forming role in THz imaging, THz holography and spatial filtering, THz nano-imaging, and computational imaging. A number of advanced THz techniques, such as light-field THz imaging, homodyne spectroscopy, and phase sensitive spectrometry, THz modulated continuous wave imaging, room temperature THz frequency combs, and passive THz imaging, as well as the use of artificial intelligence in THz data processing and optics development, will be reviewed. This roadmap presents a structured snapshot of current advances in THz imaging as of 2021 and provides an opinion on contemporary scientific and technological challenges in this field, as well as extrapolations of possible further evolution in THz imaging.

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