摘要：“近年來，光子學領域有越來越多的突破性成果，但是高影響力的期刊還是太少?！敝鞅郃natoly Zayats教授表示，“Advanced Photoni……查看詳細>>
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摘要：中科院上海光機所中國激光雜志社與國際光學工程學會（SPIE）聯合發布Advanced Photonics (AP)新刊封面。……查看詳細>>
摘要：中國激光雜志社和國際光學工程學會（SPIE）聯合創辦新刊：Advanced Photonics ……查看詳細>>
News and Commentaries
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A commentary on the article “Three-dimensional tomography of red blood cells using deep learning” by J. Lim, A. Ayoub, and D. Psaltis, Adv. Photonics Volume 2, Issue 2, doi: 10.1117/1.AP.2.2.026001.
PDF全文   HTML全文 Advanced Photonics, 2020年第2卷第2期 pp.020501-20501
Ahmed B. Ayoub
We accurately reconstruct three-dimensional (3-D) refractive index (RI) distributions from highly ill-posed two-dimensional (2-D) measurements using a deep neural network (DNN). Strong distortions are introduced on reconstructions obtained by the Wolf transform inversion method due to the ill-posed measurements acquired from the limited numerical apertures (NAs) of the optical system. Despite the recent success of DNNs in solving ill-posed inverse problems, the application to 3-D optical imaging is particularly challenging due to the lack of the ground truth. We overcome this limitation by generating digital phantoms that serve as samples for the discrete dipole approximation (DDA) to generate multiple 2-D projection maps for a limited range of illumination angles. The presented samples are red blood cells (RBCs), which are highly affected by the ill-posed problems due to their morphology. The trained network using synthetic measurements from the digital phantoms successfully eliminates the introduced distortions. Most importantly, we obtain high fidelity reconstructions from experimentally recorded projections of real RBC sample using the network that was trained on digitally generated RBC phantoms. Finally, we confirm the reconstruction accuracy using the DDA to calculate the 2-D projections of the 3-D reconstructions and compare them to the experimentally recorded projections.
PDF全文   HTML全文 Advanced Photonics, 2020年第2卷第2期 pp.026001-26001
Ultrafast lasers generating high-repetition-rate ultrashort pulses through various mode-locking methods can benefit many important applications, including communications, materials processing, astronomical observation, etc. For decades, mode-locking based on dissipative four-wave-mixing (DFWM) has been fundamental in producing pulses with repetition rates on the order of gigahertz (GHz), where multiwavelength comb filters and long nonlinear components are elemental. Recently, this method has been improved using filter-driven DFWM, which exploits both the filtering and nonlinear features of silica microring resonators. However, the fabrication complexity and coupling loss between waveguides and fibers are problematic. We demonstrate a tens- to hundreds- of gigahertz-stable pulsed all-fiber laser based on a hybrid plasmonic microfiber knot resonator device. Unlike previously reported pulse generation mechanisms, the operation utilizes the nonlinear-polarization-rotation (NPR) effect introduced by the polarization-dependent feature of the device to increase intracavity power for boosting DFWM mode-locking, which we term NPR-stimulated DFWM. The easily fabricated versatile device acts as a polarizer, comb filter, and nonlinear component simultaneously, thereby introducing an application of microfiber resonator devices in ultrafast and nonlinear photonics. We believe that our work underpins a significant improvement in achieving practical low-cost ultrafast light sources.
PDF全文   HTML全文 Advanced Photonics, 2020年第2卷第2期 pp.026002-26002
Daria A. Smirnova
Khosro Zangeneh Kamali
Yan Kei Chiang
Dragomir N. Neshev
Andrey E. Miroshnichenko
A key concept underlying the specific functionalities of metasurfaces is the use of constituent components to shape the wavefront of the light on demand. Metasurfaces are versatile, novel platforms for manipulating the scattering, color, phase, or intensity of light. Currently, one of the typical approaches for designing a metasurface is to optimize one or two variables among a vast number of fixed parameters, such as various materials’ properties and coupling effects, as well as the geometrical parameters. Ideally, this would require multidimensional space optimization through direct numerical simulations. Recently, an alternative, popular approach allows for reducing the computational cost significantly based on a deep-learning-assisted method. We utilize a deep-learning approach for obtaining high-quality factor (high-Q) resonances with desired characteristics, such as linewidth, amplitude, and spectral position. We exploit such high-Q resonances for enhanced light–matter interaction in nonlinear optical metasurfaces and optomechanical vibrations, simultaneously. We demonstrate that optimized metasurfaces achieve up to 400-fold enhancement of the third-harmonic generation; at the same time, they also contribute to 100-fold enhancement of the amplitude of optomechanical vibrations. This approach can be further used to realize structures with unconventional scattering responses.
PDF全文   HTML全文 Advanced Photonics, 2020年第2卷第2期 pp.026003-26003
Rogue waves (RWs) are rare, extreme amplitude, localized wave packets, which have received much interest recently in different areas of physics. Fiber lasers with their abundant nonlinear dynamics provide an ideal platform to observe optical RW formation. We review recent research progress on rogue waves in fiber lasers. Basic concepts of RWs and the mechanisms of RW generation in fiber lasers are discussed, along with representative experimental and theoretical results. The measurement methods for RW identification in fiber lasers are presented and analyzed. Finally, prospects for future RW research in fiber lasers are summarized.
PDF全文   HTML全文 Advanced Photonics, 2020年第2卷第2期 pp.024001-24001
Ilya Sh. Averbukh
Molecular alignment and orientation by laser fields has attracted significant attention in recent years, mostly due to new capabilities to manipulate the molecular spatial arrangement. Molecules can now be efficiently prepared for ionization, structural imaging, orbital tomography, and more, enabling, for example, shooting of dynamic molecular movies. Furthermore, molecular alignment and orientation processes give rise to fundamental quantum and classical phenomena like quantum revivals, Anderson localization, and rotational echoes, just to mention a few. We review recent progress on the visualization, coherent control, and applications of the rich dynamics of molecular rotational wave packets driven by laser pulses of various intensities, durations, and polarizations. In particular, we focus on the molecular unidirectional rotation and its visualization, the orientation of chiral molecules, and the three-dimensional orientation of asymmetric-top molecules. Rotational echoes are discussed as an example of nontrivial dynamics and detection of prepared molecular states.
PDF全文   HTML全文 Advanced Photonics, 2020年第2卷第2期 pp.024002-24002
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Microwave, which has ~10 cm long wavelength, can penetrate deeper into tissue than photons, heralding exciting deep tissue applications such as modulation or imaging via thermo-acoustic (TA) effect. However, the TA conversion efficiency is very low even with an exogenous contrast agent. Here, we break this low conversion limit through using a split ring resonator (SRR) to effectively collect and confine the microwave into a sub-millimeter hot spot for ultrasound emission, and achieve over two thousand times higher conversion efficiency than reported TA contrast agents. Importantly, the frequency of emitted ultrasound can be precisely tuned and multiplexed by modulation of the microwave pulses. This is inaccessible by a piezoelectric-based transducer or a photoacoustic emitter and opens new opportunities to study the frequency response of cells in ultrasound bio-modulations. For applications in deep tissue localization, we further harness the SRR as a wireless, battery-free ultrasound becaon placed under a breast phantom.
PDF全文 (下載：1) Advanced Photonics ，年第卷第期 pp.
Self-imaging is an important function for signal transport, distribution, and processing in integrated optics, which was usually implemented by multimode interference or diffractive imaging process. However, these processes suffer from the resolution limit due to the classical wave propagation dynamics. Here, we propose and demonstrate a subwavelength optical imaging in one-dimensional silicon waveguide arrays, which is implemented by cascading straight and curved waveguides in sequence. The coupling coefficient between the curved waveguides is tuned to be negative to reach a negative dispersion, which is an analogue to a hyperbolic metamaterial with negative refractive index. Therefore, it endows the waveguide array with a superlens function as it is connected with a traditional straight waveguide array with positive dispersion. With a judiciously engineered cascading silicon waveguide array, we successfully show the subwavelength self-imaging process of each input port of the waveguide array as the single point source. Our approach provides a new strategy in dealing with optical signal at subwavelength scale, and indicates new functional designs in high-density waveguide integrations.
Optical frequency combs, a revolutionary light source characterized with discrete and equally-spaced frequencies, are usually regarded as cornerstones for advanced frequency metrology, precision spectroscopy, high-speed communication, distance ranging, molecule detection, and so on. Thanks to the rapid development of micro/nano fabrication technology, the breakthrough in microresonator quality factor enables ultrahigh energy buildup inside cavities, which gives birth to the microcavity-based frequency combs. Especially, the full coherent spectrum of soliton microcomb provides a route to low-noise ultrashort pulses with over two orders of magnitude higher repetition rate compared with traditional modelocking approaches, which triggers intense applications in a wide range with lower power consumption and cost. In this Review, recent achievements of soliton microcombs are summarized, including the basic theory and physical model, the presented experimental techniques for single-soliton generation as well as various extraordinary soliton states (soliton crystals, Stokes solitons, breathers, molecules, cavity-solitons and dark solitons), with a perspective on their fantastic potentials and facing challenges. This work could also inspire a more comprehensive understanding of the cavity nonlinear phenomena & dynamics, promote intensive exploration of their growing potentials in future.
Dual-comb spectroscopy is an emerging spectroscopic tool with the potential to simultaneously achieve a broad spectral coverage and ultrahigh spectral resolution with rapid data acquisition. However, the need for two independently stabilized ultrafast lasers significantly hampers the potential application of dual-comb spectroscopy. In this article, we demonstrate mode-resolved dual-comb spectroscopy in the THz region based on a free-running single-cavity dual-comb fiber laser with the adaptive sampling method. While the use of a free-running single-cavity dual-comb fiber laser eliminates the need for two mode-locked lasers and their frequency control, the adaptive sampling method strongly prevents the degradation of spectroscopic performance caused by the residual timing jitter in the free-running dual-comb laser. Doppler-limit-approaching absorption features with linewidths down to 25 MHz is investigated for low-pressure acetonitrile/air mixed gas by comb-mode-resolved THz spectroscopy. The successful demonstration clearly indicates its great potential for the realization of low-complexity, Doppler-limited THz spectroscopy instrumentation.
PDF全文 (下載：0) Advanced Photonics ，年第卷第期 pp.