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The diagnosis of osteoporosis is eventually converted to the measurement of bone mineral density (BMD) in clinical trials. Since our previous work had proved the ability of using photoacoustic spectral analysis (PASA) to efficiently detect osteoporosis, in this contribution, we proposed a fully connected multi-layer deep neural network combined with PASA to semi-quantify BMD values corresponding to varying degrees of bone loss and to further evaluate the degree of osteoporosis. Experiments were carried out on swine femur heads, and the performance of our proposed method is satisfying for future clinical screening.
PDF全文   HTML全文 Chinese Optics Letters, 2020年第18卷第4期 pp.041701
We propose and analyze a silicon hybrid plasmonic polarization splitter-rotator with an ultra-short footprint using an asymmetric bent directional coupler on a silicon-on-insulator platform. Benefitting from the large birefringence induced by the bent structure and plasmonic effect, the cross-polarization coupling length is only 5.21 μm. The transverse magnetic to transverse electric polarization conversion efficiency is over 99.9%, with an extinction ratio of 20.6 dB (32.5 dB) for the transverse magnetic (transverse electric) mode at 1.55 μm. Furthermore, the polarization conversion efficiency is higher than 90% while maintaining cross talk below ?19 dB within the bandwidth of 80 nm.
PDF全文   HTML全文 Chinese Optics Letters, 2020年第18卷第4期 pp.041301
Lasers and Laser Optics
A new disordered crystal Nd:SrAl12O19 (Nd:SRA) with an Nd3+ doping concentration of 5% was successfully grown using the Czochralski method. A diode-pumped Nd:SRA Q-switched laser operating at 1049 nm was demonstrated for the first time, to the best of our knowledge. Based on an MXene Ti3C2Tx sheet, a high repetition rate of 201 kHz and a Q-switched pulse width of 346 ns were obtained when the absorbed pump power was 2.8 W. The peak power and single pulse energy were 1.87 W and 0.65 μJ, respectively.
PDF全文   HTML全文 Chinese Optics Letters, 2020年第18卷第4期 pp.041401
We demonstrate a novel multifunctional radar receiver scheme based on photonic parametric sampling. The working principle of photonic parametric sampling based on four-wave mixing (FWM) process is presented. To experimentally verify the multifunctional feasibility, the scheme is individually implemented to carry out a four-channel phased array radar reception and a dual-band radar reception.
PDF全文   HTML全文 Chinese Optics Letters, 2020年第18卷第4期 pp.042501
We experimentally demonstrated optical wireless power transfer (OWPT) using a near-infrared laser diode (LD) as the optical power transmitter. We considered a photovoltaic (PV) cell and a photodiode (PD) as the optical power receivers. We investigated the characteristics of the LD, PD, and PV cell in order to determine the optimum operating condition from the viewpoint of transfer efficiency. We also experimentally demonstrated a whole system optimization process to maximize the DC-to-DC transfer efficiency of the OWPT. Our experimental results showed that the optimization process can improve the OWPT efficiency by up to 48%.
PDF全文   HTML全文 Chinese Optics Letters, 2020年第18卷第4期 pp.042603
Imaging through scattering media via speckle autocorrelation is a popular method based on the optical memory effect. However, it fails if the amount of valid information acquired is insufficient due to a limited sensor size. In this Letter, we reveal a relationship between the detector and object sizes for the minimum requirement to ensure image reconstruction by defining a sampling ratio R, and propose a method to enhance the image quality at a small R by capturing multiple frames of speckle patterns and piecing them together. This method will be helpful in expanding applications of speckle autocorrelation to remote sensing, underwater probing, and so on.
PDF全文   HTML全文 Chinese Optics Letters, 2020年第18卷第4期 pp.042604
Plasmonics and Metamaterials
We propose a metalens for coaxial double wavelength focusing. One focusing spot is a circular solid spot, and the other focusing spot is a doughnut-shaped spot that is circling the solid spot. The designed metalens was composed of a meta-molecular nanostructured cell array. Each meta-molecular nanostructured cell was divided into four squares. Two slots with exactly the same shape, but usually with the rotation angle measured clockwise from the positive x axis, are etched into the gold film in two diagonally connected squares. Another two slots with the same shape but with the rotation angle measured counter-clockwise from the positive x axis are etched into another two diagonally connected squares in the same cell. The lasers with two different wavelengths are transformed into right-handed and left-handed circularly polarized beams, respectively. The two sets of slots with different azimuthal rotations modulated the phases of incident right-handed and left-handed circularly polarized beams independently. The numerical simulation with finite-difference time-domain (FDTD) software was carried out, and the experimental verification was also implemented. Both the experimental result and the numerical simulation agree well with the theoretical design.
PDF全文   HTML全文 Chinese Optics Letters, 2020年第18卷第4期 pp.042401
This study provides a rapid method for quantification of mineral oil in rapeseed oil using near-infrared spectroscopy. The data were processed by direct orthogonal signal correction (DOSC), successive projections algorithm (SPA), partial least squares, and principal component regression (PCR). Good correlation coefficients (R) of 0.998 and root-mean-squared error (RMSE) of 0.005 were obtained, and the DOSC-SPA-PCR model was identified as the optimal method. A satisfactory accuracy with R and RMSE of prediction by DOSC-SPA-PCR of 0.990 and 0.006, was obtained. The results demonstrate that the proposed methodology is a promising method for the rapid quantitative detection of mineral oil in vegetable oil.
PDF全文   HTML全文 Chinese Optics Letters, 2020年第18卷第4期 pp.043001
Thin Films and Optics At Surfaces
The photoelectric properties of conductive films are improved by doping Ag on aluminum-doped zinc oxide (AZO) films by laser induced forward transfer (LIFT). Firstly, the picosecond laser induced transfer mechanism of Ag films was revealed by numerical simulation; then, different-thickness Ag films were deposited on the AZO films by picosecond LIFT. When the film thickness is 30 nm and 50 nm, we have successfully obtained some Ag-AZO films with better optoelectronic properties by adjusting the laser parameters.
PDF全文   HTML全文 Chinese Optics Letters, 2020年第18卷第4期 pp.043101
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Traditional optical domes are spherical, which have a large air resistance coefficient. In order to reduce the coefficient of air resistance, conformal optical technology was proposed which used a streamlined design of the outer surface of the dome. However, Conformal domes generate dynamic aberrations varying significantly with look angles in the field of regard (FOR). Thus, correcting the dynamic aberrations is the core task of conformal optics. This paper presented a correcting method of dynamic aberrations based on the diffraction surface and anamorphic asphere surface. This method is derived from the arch corrector and can only be used on the Roll-Nod gimbal. For the seeker with a Roll-Nod gimbal, the arch corrector is replaced with a diffractive surface superimposed on the inner surface of the conformal dome. To correct astigmatism which is the main aberration that needs to be corrected, anamorphic asphere surfaces are used in the imaging system. Compared with the arch corrector, this method can reduce the size of the correction element while retaining sufficient design freedom. Design results show that this method can well correct the dynamic aberrations in a larger field of regard. With a simpler form in structure, this method can improve the reliability of conformal optical systems and promote the application of conformal optical technology.
PDF全文 (下載：0) Chinese Optics Letters ，2020年第18卷第7期 pp.07
A polarization-insensitive plasmonic absorber is designed consisting of an Au fishnet structures on TiO2 spacer/Ag mirror. The fishnet structures excite localized surface plasmon and generates hot electrons from the absorbed photons while the TiO2 layer induces Fabry-Perot resonance and the Ag acts as a back reflector. Through optimizing the TiO2 layer thickness, numerical simulation shows that 97% of the incident light is absorbed in the Au layer. The maximum responsivity and external quantum efficiency of the device can approach 5mA/W and ~1%, respectively, at the wavelength of 700nm.
PDF全文 (下載：1) Chinese Optics Letters ，2020年第18卷第5期 pp.05
Mejía E. B.
The fluorescence evolution along Tm<sup>3+</sup> doped ZBLAN optical fibers as well as amplified spontaneous emission in the UV-IR region with emphasis on 350 nm, 365 nm, and 450 nm, are studied; estimating optimal fiber lengths for amplification within the region. The fibers were diode-pumped with single- and double-line (687 and/or 645 nm). Double-line pumping presents a quite superior efficiency for producing UV-Blue signals with the benefit of requiring very short fibers, around 20 cm, compared to single-line pumping requiring more than 50 cm. A virtual cycle in which the pumps enhance each other′s absorption is the key to these systems.
PDF全文 (下載：2) Chinese Optics Letters ，2020年第18卷第7期 pp.07
An encapsulated metal-dielectric reflective grating is presented for broadband polarization-independent two-port beam splitting under normal incidence at the central wavelength of 800 nm. Different from traditional two-port grating splitters in resonant region, this grating splitter is capable of separating light energies into ±1st orders with high efficiency in a broad waveband for both TE and TM polarizations. A unified method is proposed here for designing this grating splitter, which enable one to choose a grating structure quickly to realize ultrabroad working waveband. The simulation results indicate that a bandwidth of 46.4nm could be achieved for diffraction efficiency (defined as the ratio of the light energy diffracted only at the first order to the incident light) over 46% at the central wavelength of 800 nm. Moreover, the parameters of the grating structure can be flexibly adjusted with wavelength using the unified method for various other applications, such as augmented reality, optical interconnections for computing, coherent beam combination, complex vector beam shaping, and so on.
PDF全文 (下載：8) Chinese Optics Letters ，2020年第18卷第7期 pp.07
An asymmetrical tapered singlemode-multimode-singlemode (SMS) fiber coupler based on two parallel physical contact SMS fiber structures was proposed. Since the coupler includes modes both from fiber core and cladding, two dips of the transmission spectrum exhibit different sensing characteristic to surrounding temperature and refractive index (RI) change, which allows using the standard matrix inversion method to determinate temperature and RI simultaneously. For biosensing application, with the functionalized fiber coupler sensor, an human chorionic gonadotropin (hCG) concentration of 0.05 mIU/mL has been detected for wavelength shift of 0.2 nm with good stability and excellent selectivity. The developed tapered SMS fiber coupler structure has advantage of simultaneous measurement of two independent parameters, simple configuration, low cost and good repeatability that offers a great potential for medical diagnostics.
PDF全文 (下載：3) Chinese Optics Letters ，2020年第18卷第7期 pp.07
By controlling the wavelength and power of multiple light sources, we have realized a highly flexible Nyquist pulse generation scheme in which the pulse repetition frequency, pulse multiplication factor, waveform envelope shape and duty cycle are all tunable. By modulating the 3.2 GHz RF signal, we experimentally generated Nyquist pulses with a repetition rate of 6.4 GHz and 9.6 GHz and a rectangular wave with a duty cycle of 0.26 and a sawtooth wave with a duty cycle of 0.52.
PDF全文 (下載：1) Chinese Optics Letters ，2020年第18卷第7期 pp.07
We report 25-Gb/s high-speed directly-modulated ground-state operation of 1.3-μm InAs/GaAs quantum dot lasers grown by molecular beam epitaxy. The active region of the lasers consists of eight layers of p-doped InAs QDs with high uniformity and density. Ridge-waveguide lasers with a 3-μm-wide and 300-μm-long cavity show a low threshold current of 14.4mA at 20℃ and high temperature stability with a high characteristic temperature of 1208K between 20℃ and 70℃. Dynamic response measurements demonstrate that the laser has a 3dB bandwidth of 7.7GHz at 20℃ and clearly-opened eye diagrams even at high temperatures up to 75℃ under a 25-Gb/s direct-modulation rate.
We demonstrate a microwave photonic radar with post-bandwidth synthesis, which can realize target detection with ultra-high range resolution using relatively small-bandwidth radio frequency (RF) frontends. In the proposed radar, two temporal-overlapped linear frequency-modulated (LFM) signals with the same chirp rate and different center frequencies are transmitted. By post-processing the de-chirped echos in the receiver, a signal equivalent to that de-chirped from an LFM signal with the combined bandwidth is achieved. In a proof-of-concept experiment, two LFM signals with bandwidths of 8.4 GHz are exploited to achieve radar detection with an equivalent bandwidth of 16 GHz, and a range resolution of 1 cm is obtained.
In this letter, we find that Morse potential (proposed about 90 years ago) could be connected to Coulomb potential (or Newton potential) and harmonic potential (or Hooke potential) by conformal mappings. We thereby design a new conformal lens from Morse potential, Eaton lens and Luneburg lens and propose a series of generalized Eaton/Luneburg lenses. We find that this Morse lens is a perfect self-focusing asymmetric lens, which differs from Mikaelian lens. Our theory provides a new insight to Morse potential and other traditional potentials and revisits their classical applications on designing lenses.
PDF全文 (下載：0) Chinese Optics Letters ，2020年第18卷第6期 pp.06
In order to achieve the accurate measurement of displacement, this paper presents a self-mixing interference (SMI) displacement measurement method suitable for speckle effect. Because of the speckle effect, the amplitude of SMI signal fluctuates greatly, which will affect the measurement accuracy of displacement. EEMD is used to process SMI signal, which can filter out high-frequency noise and low-frequency noise at the same time. The envelope of SMI signal is extracted by Hilbert transform and it is used to realize the normalization of SMI signal. Through a series of signal processing, the influence of speckle on SMI signal can be effectively reduced and the SMI signal can be transformed into standard form. The displacement can be reconstructed by fringe counting and interpolation method. The experimental results show that the method is successfully applied to the displacement measurement in the presence of speckle, which verifies the effectiveness and feasibility of the method.
PDF全文 (下載：0) Chinese Optics Letters ，2020年第18卷第5期 pp.05
A 21.2 kW, 1.94 times diffraction limited quasi-continuous wave laser is presented in this Letter based on a multi-stage, power-scalable Yb:YAG master-oscillator-power-amplifier (MOPA) system under adaptive optics (AO) control. Output laser of the MOPA system is a rectangular beam with a length-width ratio of 2:1, a 200 μs pulse duration and a 1000 Hz repetition rate. With the AO control system, the beam quality of the laser is improved from 4.20 to 1.94 times diffraction limited. To our knowledge, this is the best quality laser in the 20-kW class except for combined lasers.
PDF全文 (下載：1) Chinese Optics Letters ，2020年第18卷第6期 pp.06
We report a new method to deeply analyze the scrambling characteristic of polarization scramblers based on density of polarization states (DPS) statistics, which makes it possible to describe the DPS distribution in detail on the whole Poincaré Sphere, thus easy to locate accurately the nonuniform areas of defective polarization scramblers, which can not be realized by existing methods. We have built a polarization scrambling system to demonstrate the advantages of our method compared with others by experiments, and suggested effective evaluation indexes whose validity is well confirmed by applying to commercial scrambler. Our conclusions are valuable for accurate analyzing and diagnosing the performance of any polarization scrambler, and quality evaluation of polarization controllers or other polarization devices.
PDF全文 (下載：6) Chinese Optics Letters ，2020年第18卷第6期 pp.06
Khalid Ata Ur Rahman
We propose and numerically demonstrate a dynamic beam deflector based on plasmonic resonators loaded thermo-responsive free-standing hydrogel which swells and collapses in water by temperature. For this purpose, we utilize four-step phase gradients mounted on free-standing hydrated hydrogel. For the normal incidence, the linearly orthogonal light deflects to 19.44° in collapsed state and 14.40° in swollen state of hydrogel. Furthermore, the light deflects at third angle i.e. 12.29° when solvent changes from water to ethanol. It is expected that our meta-design will provide a platform for dynamic holography, active lensing, data storage and, anti-counterfeiting.
PDF全文 (下載：13) Chinese Optics Letters ，2020年第18卷第6期 pp.06
All-optical light control plays an important role in optical signal processing and communications. In this letter, we demonstrate the all-optical inverter using the carbon nanotubes (CNT)-polyvinyl alcohol (PVA) thin film and obtain a long time stable output due to the environmental insensitivity of the device. Thermo-optic effect in the CNT-PVA thin film generates a thermal lens and modifies the beam propagation in the thin film. The obtained all-optical inverter has a front (trailing) time constant of ~ 55 μs (44 μs) for 1550 nm signal pulses and ~7 kHz response bandwidth.
In the paper a method for shape visualization of small objects (microscopic) in the form of a hologram is presented. It consists of standard optical set-up for small object registration (i.e. stereoscopic or biological microscope). The Focus Stacking (FS) technique is used to obtain series of images with increased depth of field and on them a shape reconstruction procedure (Structure from Motion – SfM) is made. With use of a dense cloud of points a sequence of parallax-related images suitable for Geola’s digital holographic printing is generated. Holographic printer produces single parallax holographic (full 3D) images of real or virtual objects.
Broadband transverse displacement sensing by exploiting the interaction of a focused radially polarized (RP) beam with a silicon hollow nanodisk is proposed. The multipolar decomposition analysis indicates that the interference between a longitudinal total electric dipole (TED) moment and a lateral magnetic dipole (MD) moment is dominant in the far-field transverse scattering in the near-infrared region. Within a broadband wavelength range with the width of 155nm, the longitudinal TED is almost in phase with the lateral MD and then broadband position sensing based on the sensitivity of scattering directivity to transverse displacement can be achieved.
An equivalent circuit model including multi-section distributed parameters is proposed to analyze wideband photodiodes (PDs) with coplanar waveguide (CPW) electrodes. The model helps extract CPW parameters as well as intrinsic bandwidth parameters, so that the influence of CPW structure can be investigated, making it valuable for the design of high performance PDs. PDs with an inductive 115-Ω impedance CPW are fabricated, and the 3-dB bandwidth is improved from 28 GHz to 37.5 GHz, compared with PDs with conventional 50-Ω impedance CPW.
PDF全文 (下載：3) Chinese Optics Letters ，2020年第18卷第6期 pp.06
This letter proposes a model of indoor VLC heterogeneous networks entirely based on LEDs with different specifications and applies non-orthogonal multiple access (NOMA) to it because of the narrow modulation bandwidth of LEDs. Moreover, a user-grouping scheme which is based on matching theory is proposed to improve the network achievable sum rate. Simulation results indicate that when each NOMA cluster contains 6 users, the proposed scheme has 49.54% sum-rate enhancement compared with the traditional user-grouping scheme. As the number of users in each NOMA cluster increases, the proposed scheme performs better at the cost of computational complexity.
PDF全文 (下載：4) Chinese Optics Letters ，2020年第18卷第6期 pp.06
Rotating elliptical nanowire arrays as the two-dimensional photonic crystals has been proposed and studied in this letter. The analysis of the four lowest energy band and first band gap width of some examples illustrates that the rotation and configuration of the primitive cell can have effects on the reducibility of Brillouin zone. As the central element’s orientation changes, the irreducible Brillouin zone could be expanded to the whole first Brillouin zone. Special attention has been paid to the nanowire arrays with adjacent elements perpendicular to each other, and the irreducible Brillouin zone unexpectedly retracted back to the 1/8 of the first Brillouin zone though the symmetry of elements is lower than that of the square lattice. Meanwhile, the first band gap width of the perpendicular array can be adjusted by the rotation of each primitive element.
PDF全文 (下載：2) Chinese Optics Letters ，2020年第18卷第6期 pp.06
We experimentally demonstrated that the DFB lasers with active distributed reflector achieved a 25.8 Gb/s operation over wide temperature range of -40 – 85 oC. The DFB lasers can achieve additional feedback from active distributed reflector with accurately controlled phase, and single mode yield are not related to the position of cleave. The threshold current of the fabricated laser are 6 mA and 20 mA at -40 oC and 85 oC, respectively. The side mode suppression ratio of the fabricated laser is above 50 dB at all temperature. 25.8 Gb/s transmissions after 10-km single-mode fibers with clear eye openings and less-than 0.8 dB power penalty over a wide temperature range have been demonstrated as well.
In recent years, multi-wavelength fiber lasers play a significant role in plenty of fields, ranging from optical communications to mechanical processing and laser biomedicine owning to their high beam quality, low cost and excellent heat dissipation properties. Benefitting from increasing maturity of optical elements, multi-wavelength fiber laser has got rapid developments. In this review, we summarize and analyze diverse implementation methods covering continuous wave (CW) and pulsed fiber laser at room temperature condition: inserting optical filter device and intensity-dependent loss structure in the resonant cavity, applying ultrafast nonlinear optical response of materials and dual-cavity structure. Finally, future challenges and perspectives of multi-wavelength fiber laser are discussed and addressed.
PDF全文 (下載：3) Chinese Optics Letters ，2020年第18卷第4期 pp.04
An aberration-free imaging technique was used to design a double-spherically bent crystal spectrometer with high energy and spatial resolution to ensure that the individual spectral lines are represented as perfectly straight lines on the detector. After obtaining the matched parameters of the two crystals via geometry-based optimization, an alignment method was employed to allow the spacing between the crystals and the detector to be coupled with the source. The working principle of this spectrum-measuring scheme was evaluated using a Cu X-ray tube. High-quality spectra with energy resolution (E/ΔE) of approximately 3577 were obtained for a relatively large source size.
To fully describe the structure information of the point cloud when the LIDAR-object distance is far, a joint global and local feature (JGLF) descriptor is constructed. Compared with five typical descriptors, the object recognition rate of JGLF is higher when the LIDAR-object distances change. Under the situation that airborne LIDAR is getting close to the object, particle filtering (PF) algorithm is used as the tracking frame. And particle weight is updated by comparing the difference between JGLFs to track the object. It is verified that the proposed algorithm performs 13.95% more accurate and stable than that of the basic PF algorithm.
We report the first demonstration of group delay tuning with stimulated Raman scattering induced dispersion in a hydrogen-filled hollow-core optical fiber. A pump laser induces sharp refractive index change near the S0(0) Raman transition of hydrogen molecules, enabling the control of the group velocity of signal pulses around the Stokes wavelength. Experiment with an 80-m-long hollow-core fiber filled with 2.5-bar hydrogen achieved continuously tuning of pulse delay up to 1.42 ns by varying the Raman gain from 0-10 dB. Tunable pulse delay is realized by changing pump power as well as hydrogen pressure. This work provides a new technique for controlling pulse propagation in optical fibers with high flexibility.
Polarization aberration caused by material birefringence can be partially compensated by lens clocking. In this paper, we propose a fast and efficient clocking optimization method. Firstly, the material birefringence distribution is fitted by the orientation Zernike polynomials. On this basis, the birefringence sensitivity matrix of each lens element can be calculated. Then we derive the rotation matrix of the orientation Zernike polynomials and establish the mathematical model for clocking optimization. Finally, an optimization example is given to illustrate the efficiency of the new method. The result shows that the maximum RMS of retardation is reduced by 64% using only 48.99s.
Refractive index enhancement is crucial in the field of lithography, imaging, optical communications, solar devices and many more. We present a review of advancements in the process of designing high refractive index metamaterials, starting from quantum coupling and photonic bandgap materials to metamaterials utilizing deep subwavelength coupling to achieve ever-high values of refractive index. A particular interest is given to experimentally verified schemes in engineering high index of refraction. The Understanding of evolution of material design from intrinsic electronic states manipulation to meta-atoms design is not only fascinating but prerequisite to developing successful devices and applications.
Photonic waveguide arrays provide a simple and versatile platform for simulating conventional topological systems. Here we investigate a novel one-dimensional (1D) topological band structure, a dimer chain, consisting of silicon waveguides with alternating self-coupling and inter-coupling. Coupled mode theory is used to study topological features of such model. It is found that topological invariants of our proposed model are described by the global Berry phase instead of the Berry phase of the upper or lower energy band, which is commonly used in the 1D topological models such as SSH model. Next, we design an array configuration composed of two dimer patterns with different global Berry phases to realize the topologically protected waveguiding. The topologically protected propagation feature is simulated based on Finite-Difference Time-Domain (FDTD) method and then observed in the experiment. Our results provide an in-depth understanding of the dynamics of the topological defect state in a 1D silicon waveguide array, and may provide different routes for on-chip lightwave shaping and routing.
PDF全文 (下載：23) Chinese Optics Letters ，2020年第18卷第5期 pp.05
We propose here a novel method for position fixing in micron-scale by combining the convolutional neural networks (CNN) architecture and speckle patterns generated in a multimode fiber. By varying the splice offset between a single mode fiber and a multimode fiber, speckles with different patterns can be generated at the output of the multimode fiber. The CNN is utilized to learn these specklegrams and then predict the offset coordinate. Simulation results show that predicted positions with the precision of 2 μm account for 98.55%. This work provides a potential high-precision two-dimensional positioning method.
PDF全文 (下載：10) Chinese Optics Letters ，2020年第18卷第5期 pp.05
In this paper, the surface-enhanced Raman scattering (SERS)signal of BRC patient serum obtained by a porous silicon (PSi) Bragg reflector with silve nanoparticles(Ag NPs). Based on these advantages, the serum SERS of 30 normal people and 30 BRC patients were detected by this substrate. After abaseline correction of the experimental data, principal component analysis and linear discriminant analysis (PCA-LDA) were used to complete the data processing. The results showed that the diagnostic accuracy, specificity and sensitivity of the PSi Bragg reflector SERS substrate with composite Ag NPs were 95%, 96.7%, and 93.3%respectively. The results of this exploratory study prove that the detection of BRC serum based on the composite Ag NPs PSi Bragg reflector SERS substrate is a stable, strong SERS signal, unmarked and noninvasive BRC diagnosis technology. In the future, this technology can serve as anoninvasiveclinical tool to detect cancer diseases and have a consider able impact on clinical medical detection.
PDF全文 (下載：6) Chinese Optics Letters ，2020年第18卷第5期 pp.05
Laser induced discharge plasma (LDP) can be used as inspection and metrology EUV sources for its simplicity. To avoid the tin electrode erosion, a LDP EUV source, in which a tin pool was used as cathode, was developed. A CO2 pulse laser was focused on the liquid tin target surface, and then a breakdown occurred in a very short time. The voltage-current characteristics of the discharge oscillated, and lasted for several microseconds, and a RLC fitting model was used to obtain the inductance and resistance. An ICCD camera was used to investigate the dynamic of LDP, which can explain the formation of a discharge channel. The EUV spectra of laser induced liquid tin discharge plasma were detected by a grazing incident ultraviolet spectrometer, compared with laser produced tin droplet plasma EUV spectrum. To explain the EUV spectra difference of laser induced liquid tin discharge plasma and laser produced tin droplet plasma, the collision radiation (CR) model combined with COWAN code was used to fit the experimental EUV spectrum, which can estimate the electron temperature and density of the plasma.
PDF全文 (下載：3) Chinese Optics Letters ，2020年第18卷第5期 pp.05