scholarly journals Spectrally multimode integrated SU(1,1) interferometer

Quantum ◽  
2021 ◽  
Vol 5 ◽  
pp. 461
Author(s):  
Alessandro Ferreri ◽  
Matteo Santandrea ◽  
Michael Stefszky ◽  
Kai H. Luo ◽  
Harald Herrmann ◽  
...  
Keyword(s):  
Continuous Wave ◽  
Single Mode ◽  
Potassium Titanyl Phosphate ◽  
Destructive Interference ◽  
Phase Sensitivity ◽  
Polarization Converter ◽  
Two Photon ◽  
Integrated Architecture ◽  
On Chip ◽  
Detection Strategies

Nonlinear SU(1,1) interferometers are fruitful and promising tools for spectral engineering and precise measurements with phase sensitivity below the classical bound. Such interferometers have been successfully realized in bulk and fiber-based configurations. However, rapidly developing integrated technologies provide higher efficiencies, smaller footprints, and pave the way to quantum-enhanced on-chip interferometry. In this work, we theoretically realised an integrated architecture of the multimode SU(1,1) interferometer which can be applied to various integrated platforms. The presented interferometer includes a polarization converter between two photon sources and utilizes a continuous-wave (CW) pump. Based on the potassium titanyl phosphate (KTP) platform, we show that this configuration results in almost perfect destructive interference at the output and supersensitivity regions below the classical limit. In addition, we discuss the fundamental difference between single-mode and highly multimode SU(1,1) interferometers in the properties of phase sensitivity and its limits. Finally, we explore how to improve the phase sensitivity by filtering the output radiation and using different seeding states in different modes with various detection strategies.

scholarly journals Ultra-low-loss on-chip zero-index materials

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Tian Dong ◽  
Jiujiu Liang ◽  
Sarah Camayd-Muñoz ◽  
Yueyang Liu ◽  
Haoning Tang ◽  
...  
Keyword(s):  
Spatial Coherence ◽  
Single Mode ◽  
Nonlinear Propagation ◽  
Small Scale ◽  
Destructive Interference ◽  
Dirac Cone ◽  
Large Area ◽  
Low Loss ◽  
On Chip ◽  
Zero Index

AbstractLight travels in a zero-index medium without accumulating a spatial phase, resulting in perfect spatial coherence. Such coherence brings several potential applications, including arbitrarily shaped waveguides, phase-mismatch-free nonlinear propagation, large-area single-mode lasers, and extended superradiance. A promising platform to achieve these applications is an integrated Dirac-cone material that features an impedance-matched zero index. Although an integrated Dirac-cone material eliminates ohmic losses via its purely dielectric structure, it still entails out-of-plane radiation loss, limiting its applications to a small scale. We design an ultra-low-loss integrated Dirac cone material by achieving destructive interference above and below the material. The material consists of a square array of low-aspect-ratio silicon pillars embedded in silicon dioxide, featuring easy fabrication using a standard planar process. This design paves the way for leveraging the perfect spatial coherence of large-area zero-index materials in linear, nonlinear, and quantum optics.

Source-Corrected Two-Photon Excited Fluorescence Measurements between 700 and 880 nm

1998 ◽  
Vol 52 (4) ◽  
pp. 536-545 ◽  
Author(s):  
W. G. Fisher ◽  
E. A. Wachter ◽  
Fred E. Lytle ◽  
Michael Armas ◽  
Colin Seaton
Keyword(s):  
Continuous Wave ◽  
Group Velocity Dispersion ◽  
Dispersion Compensation ◽  
Average Power ◽  
Single Mode ◽  
Wavelength Dependence ◽  
Power Correction ◽  
Two Photon ◽  
Fluorescence Measurements ◽  
Photon Excitation

Passively mode-locked titanium:sapphire (Ti:S) lasers are capable of generating a high-frequency train of transform-limited subpico-second pulses, producing peak powers near 105 W at moderate average powers. The low energy per pulse (<20 nJ) permits low fluence levels to be maintained in tightly focused beams, reducing the possibility of saturating fluorescence transitions. These properties, combined with a wavelength tunability from approximately 700 nm to 1 μm, provide excellent opportunities for studying simultaneous two-photon excitation (TPE). However, pulse formation is very sensitive to a variety of intracavity parameters, including group velocity dispersion compensation, which leads to wavelength-dependent pulse profiles as the wavelength is scanned. This wavelength dependence can seriously distort band shapes and apparent peak heights during collection of two-photon spectral data. Since two-photon excited fluorescence is proportional to the product of the peak and average powers, it is not possible to obtain source-independent spectra by using average power correction schemes alone. Continuous-wave, single-mode lasers can be used to generate source-independent two-photon data, but these sources are four to five orders of magnitude less efficient than the mode-locked Ti:S laser and are not practical for general two-photon measurements. Hence, a continuous-wave, single-mode Ti:S laser has been used to collect a source-independent excitation spectrum for the laser dye Coumarin 480. This spectrum may be used to correct data collected with multimode sources; this possibility is demonstrated by using a simple ratiometric method to collect accurate TPE spectra with the mode-locked Ti:S laser. An approximate value of the two-photon cross section for Coumarin 480 is also given.

scholarly journals Measurement of two-photon absorption by gold nanoparticles of different sizes photodeposited onto the core of an optical fibre

2021 ◽  
Vol 61 (1) ◽  
Author(s):  
J.M. Cuvas-Limón ◽  
J.G. Ortega-Mendoza ◽  
J.P. Padilla-Martínez ◽  
P. Zaca-Morán
Keyword(s):  
Gold Nanoparticles ◽  
Optical Fibre ◽  
Continuous Wave ◽  
Nonlinear Coefficient ◽  
Single Mode ◽  
High Gain ◽  
Photon Absorption ◽  
Two Photon Absorption ◽  
Two Photon ◽  
The Core

In this work, the study of two-photon absorption by gold nanoparticles of different diameters photodeposited onto the core of a single-mode optical fibre is presented. The photodeposition of nanoparticles with diameters of 10, 20, 50 and 100 nm was achieved using a continuous wave laser at a wavelength of 1550 nm and a power of 50 mW. Nonlinear optical characterization was carried out by using the P-scan technique of a high gain erbium doped fibre amplifier with pulses of 20 ns at a frequency of 10 kHz, that provides a maximum intensity of approximately 60 MW/cm2. The results show that for gold nanoparticles greater than 20 nm photodeposited onto the fibre, in both cases, the nonlinear coefficient as well as the third-order susceptibility increase as the diameter of the nanoparticles increases, describing a typical behaviour of the two-photon absorption. The obtained results can be used for the design of filters and optical limiters in the communications area.

A High Speed and Ultra Long-Haul Radio-Over-Fiber System Employing Dual Photoelectric Arms Coherent Modulation and Optical Duo-Binary Coding

2014 ◽  
Vol 988 ◽  
pp. 544-547
Author(s):  
Guang Li
Keyword(s):  
High Speed ◽  
Continuous Wave ◽  
Single Mode ◽  
Fiber Amplifier ◽  
Radio Over Fiber ◽  
Laser Source ◽  
Signal Spectrum ◽  
Fiber System ◽  
Binary Coding ◽  
Coherent Modulation

A novel high speed and ultra long-haul radio-over-fiber (ROF) system based on Dual Photoelectric Arms Coherent Modulation (DPACM) and Optical Duo-Binary Coding (ODBC) is proposed, and demonstrated. The signal spectrum bandwidth, generated by ODBC based on the first order DPACM, is half of non-return-to-zero (NRZ ) signal spectrum bandwidth. The secondary order DPACM generates a 40-GHz Millimeter-wave (mm-wave) that is transmitted over fiber (ROF). The simulation results show that, the bit rate can be up to 40 Gbps and the transmission distance is over 1500 Km, based on the ROF system with a 0 dBm continuous-wave laser source, multiple stages Er-Doped Fiber Amplifier (EDFA), a standard single mode fiber (SSMF) with a dispersion of 17 ps/nm/Km and a attenuation of 0.2 dB/Km.

scholarly journals Coherent control of acoustic phonons in a silica fiber using a multi-GHz optical frequency comb

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Mamoru Endo ◽  
Shota Kimura ◽  
Shuntaro Tani ◽  
Yohei Kobayashi
Keyword(s):  
Coherent Control ◽  
Continuous Wave ◽  
Frequency Comb ◽  
Effective Interaction ◽  
Interaction Strength ◽  
Single Mode ◽  
Optical Frequency Comb ◽  
Material Structure ◽  
Optical Frequency ◽  
Acoustic Phonons

AbstractMulti-gigahertz mechanical vibrations that stem from interactions between light fields and matter—known as acoustic phonons—have long been a subject of research. In recent years, specially designed functional devices have been developed to enhance the strength of the light-matter interactions because excitation of acoustic phonons using a continuous-wave laser alone is insufficient. However, the strength of the interaction cannot be controlled appropriately or instantly using these structurally-dependent enhancements. Here we show a technique to control the effective interaction strength that does not operate via the material structure in the spatial domain; instead, the method operates through the structure of the light in the time domain. The effective excitation and coherent control of acoustic phonons in a single-mode fiber using an optical frequency comb that is performed by tailoring the optical pulse train. This work represents an important step towards comb-matter interactions.

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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