## 留言板

The stimulated Brillouin scattering in As2S3 photonic crystal fibers were investigated at wavelength of 2 μm to 6 μm by the finite element method. The numerical results indicate that the proposed photonic crystal fiber can maintain single-mode operation when the air filling factor is less than 0.6. The Brillouin frequency shift is mainly influenced by the pump wavelength and fiber structure. The Brillouin frequency shift decreases by 4.16 GHz when the pump wavelength is increased from 2 μm to 6 μm, while the Brillouin frequency shift changes by megahertz order when the air filling rate increases from 0.5 to 0.6. The FWHM of the Brillouin gain spectrum depends on the phonon lifetime, and the FWHM of the Brillouin gain spectrum is nine times wider at a pump wavelength of 2 μm than at a pump wavelength of 6 μm. The maximum Brillouin gain of the proposed fibers with air filling fractions of 0.5 and 0.6 are 2.413×10−10 m/W and 2.429×10−10 m/W, respectively. The Brillouin threshold is positively correlated with the pump wavelength for the same effective fiber length, and is 27.8% and 19.6% larger at a pump wavelength of 6 μm than that at 2 μm with air fill factors of 0.5 and 0.6, respectively. The numerical results are of great significance for the design and fabrication of optical devices or optical sensors based on the proposed fibers in the mid-infrared band.

In order to achieve high spectral responsivity of the silicon avalanche photodiode in blue band (400−500 nm), Separated Absorption Control Mul-tiplication (SACM) basic device structure was designed. Based on multiple physical models, the effect of the thickness on the avalanche breakdown voltage and the photocurrent gain of the device and the effect of the doping concentration of the multiplication layer on the optical responsivity were investigated. Comprehensively considering the factors of light responsivity and breakdown voltage, the results show that the device has a low breakdown voltage Vbr-apd=34.2 V when the doping concentration of the surface non-depleted layer is 1.0×1018 cm−3, and the thickness is 0.03 μm; the doping concentration of absorption layer is 1.0×1015 cm−3, the thickness is 1.3 μm, the doping concentration of field control layer is 8.0×1016 cm−3, the thickness is 0.2 μm and the doping concentration of double layer is 1.8×1016 cm−3 and the thickness is 0.5 μm. When Vapd=0.95Vbr-apd, it has higher optical responsivity in blue band, i.e. SR=3.72~6.08 A·W−1. The above research results provide certain theoretical reference for the preparation of practical Si-APD devices with high blue light detection responsivity.

In order to improve the detection efficiency of Micro Array Electrodes (MAE) and reduce the production cost, a technology combining Digital Micromirror Device (DMD) maskless projection lithography with electrochemical deposition was proposed. Firstly, a user-defined micro array was fabricated by using the advantages of lithography system such as high-resolution PZS motion and imaging flexibility of DMD. And a uniform Au microarray electrode (Au/MAE) was fabricated after obtaining an Au conducting layer by electrodeposition. Then, the electrochemical properties of Au/MAE with different structures were compared by cyclic voltammetry, and the optimized structural parameters were obtained. Finally, the current response of optimized Au/MAE to the glucose with different concentrations and pH values was studied, and the anti-interference of Au/MAE in glucose detection was tested by chronoamperometry. The electrochemical analysis shows that the simple Au/MAE has a significant amperometric response, a strong anti-interference ability and a sensitivity of 101 μA·cm−2·mM−1 in the electrochemical detection of glucose. This method has the advantages of high resolution, high consistency, simple process and low cost, which provides a feasible operation scheme for the fabrication of biosensor array.

Spectral irradiance degradation of a halogen tungsten lamp increases the spectral radiance uncertainty of an on-board lamp-diffuser calibrator, composed of a lamp and a diffuser reflector. Therefore, it was necessary to investigate the degradation characteristics of the lamp to improve this spectral radiance uncertainty. A spectral irradiance degradation model of a halogen tungsten lamp with undetermined order at wavelength from 400 nm to 1300 nm was proposed according to the blackbody radiation law and Weierstrass theorem. The model order was determined as the minimum to satisfy the reconstruction uncertainty required by the spectral radiance of the on-board lamp-diffuser calibrator. According to which, the model order was determined to be two. The reconstruction uncertainty of the spectral irradiance degradation curve was better than 0.25% according to the two-order model, which lays a theoretical foundation to improve the spectral radiance uncertainty of the on-board lamp-diffuser calibrator.

2022, 15(2): 161-186.   doi: 10.37188/CO.2021-0143
[摘要](717) [HTML全文](233) [PDF 5743KB](257)

2022, 15(2): 187-209.   doi: 10.37188/CO.EN.2021-0012
[摘要](504) [HTML全文](205) [PDF 7522KB](153)

Oxide Vertical Cavity Surface Emitting Lasers(VCSELs) are widely used in high-speed optical communications. The reliability of VCSELs is a very important index that requires a high lifetime and low failure rate in the application process. Understanding the root causes and mechanisms of VCSEL failure is necessary and helpful to improve device reliability. In this paper, we summarize and analyze the most common failure modes, causes and mechanisms observed in oxide VCSELs from the perspective of design, manufacturing and application, then apply some appropriate measures and suggestions to prevent or improve them. Moreover, the three dominating factors leading to the failure of VCSELs including oxide layer stress, Electronic Static Discharge (ESD) and humidity corrosion are introduced in more detail. At last, we simply introduce the VCSEL failure cases encountered in the actual accelerated aging verification process. This article can be used as a good VCSEL failure analysis library for chip development and production researchers.

2022, 15(2): 210-223.   doi: 10.37188/CO.2021-0176
[摘要](482) [HTML全文](167) [PDF 6613KB](129)

2022, 15(2): 224-232.   doi: 10.37188/CO.2021-0142
[摘要](227) [HTML全文](99) [PDF 2504KB](64)

2022, 15(2): 233-241.   doi: 10.37188/CO.2021-0205
[摘要](145) [HTML全文](70) [PDF 5931KB](46)

2022, 15(2): 242-250.   doi: 10.37188/CO.2021-0160
[摘要](222) [HTML全文](67) [PDF 3935KB](61)

2022, 15(2): 251-258.   doi: 10.37188/CO.2021-0158
[摘要](194) [HTML全文](71) [PDF 3808KB](48)

2022, 15(2): 259-266.   doi: 10.37188/CO.2021-0232
[摘要](145) [HTML全文](67) [PDF 6901KB](49)

2022, 15(2): 267-275.   doi: 10.37188/CO.2021-0170
[摘要](161) [HTML全文](79) [PDF 3226KB](61)

2022, 15(2): 276-285.   doi: 10.37188/CO.2021-0157
[摘要](206) [HTML全文](131) [PDF 4176KB](48)

2022, 15(2): 286-296.   doi: 10.37188/CO.2021-0152
[摘要](222) [HTML全文](98) [PDF 3781KB](51)

2022, 15(2): 297-305.   doi: 10.37188/CO.2021-0162
[摘要](176) [HTML全文](84) [PDF 2581KB](40)

2022, 15(2): 306-317.   doi: 10.37188/CO.2021-0130
[摘要](243) [HTML全文](88) [PDF 4869KB](95)

2022, 15(2): 318-326.   doi: 10.37188/CO.2021-0106
[摘要](326) [HTML全文](136) [PDF 7371KB](49)

2022, 15(2): 327-338.   doi: 10.37188/CO.2021-0144
[摘要](249) [HTML全文](133) [PDF 4328KB](51)

2022, 15(2): 339-347.   doi: 10.37188/CO.2021-0132
[摘要](346) [HTML全文](124) [PDF 7406KB](84)

2022, 15(2): 348-354.   doi: 10.37188/CO.2021-0119
[摘要](405) [HTML全文](162) [PDF 5283KB](84)

2022, 15(2): 355-363.   doi: 10.37188/CO.2021-0089
[摘要](427) [HTML全文](174) [PDF 5767KB](55)

2022, 15(2): 364-372.   doi: 10.37188/CO.EN.2021-0010
[摘要](191) [HTML全文](92) [PDF 2384KB](32)

In this paper, an averaged intensity and spectral shift of Partially Coherent Chirped Optical Coherence Vortex Lattices (PCCOCVLs) in biological tissue turbulence are investigated with emphasis on optical lattice structures in monochromatic optical fields and spectral rapid transitions in polychromatic optical fields. It is found that the beam profile evolves from annular structures with a vortex core into a periodic array of lobes with a dark zone, and finally presents a Gaussian-like pattern in biological tissue. Although lattice parameter modulates beam profile, it cannot affect the spectral behavior in biological tissue turbulence. The analysis of spectral shift also shows that a smaller distance is beneficial to spectral rapid transition where the transverse coordinate decreases with an increase in chirp parameter and a decrease in pulse duration. The accumulated turbulences over a longer distance can suppress not only spectral transition but also spectral shift. The reduction of spectral shift is accompanied by stronger biological tissue turbulence. The results have possible application in image recognition, medical devices and noninvasive optical diagnoses in biological tissue.
2022, 15(2): 373-386.   doi: 10.37188/CO.2021-0149
[摘要](308) [HTML全文](113) [PDF 4758KB](56)

With the advantages such as simple structure, simple process and easy interface control, the photoelectric devices based on carbon nanomaterial/bulk semiconductor van der Waals (vdW) heterojunctions can fully realize the ultrahigh carrier mobility of carbon nanomaterials and the excellent photoelectric properties of bulk semiconductors. Especially, the novel mixed-dimensional vdW heterojunctions can be prepared by controlling the diameter/chirality and Fermi level of single-walled carbon nanotubes (SWCNTs) to form atomic-level interfaces and match bandgaps with bulk semiconductors. Here, we reported a self-powered broadband photodetector based on the pn vdW heterojunctions by combining (6, 5)-enriched semiconducting SWCNT film with n-type GaAs, and used graphene to reduce the probability of carrier recombination in SWCNT film and to promote the carrier transport. The experimental results suggest that the self-powered device exhibits high-sensitivity photoelectric response toward the incident photons in the 405~1064 nm range, and that the max photoelectric responsivity of 1.214 A/W and the specific detectivity of 2 × 1012 Jones could be achieved at zero bias.
2022, 15(2): 387-403.   doi: 10.37188/CO.2021-0174
[摘要](149) [HTML全文](60) [PDF 5548KB](57)

A wide-band and narrow-band switchable bi-functional metamaterial absorber is presented in this paper. The phase change material vanadium dioxide (VO2) is introduced in the structure of the metamaterial absorber, and different functions can be achieved by using only a single switchable metasurface. The mutual conversion of different functions is realized by the reversible phase transition between the VO2 insulating state and the metal state. When VO2 is in metallic state, the designed structure can be regarded as a metamaterial wide-band absorber. The simulation results show that the absorption is over 98% in the frequency range of 1.55 THz to 2.21 THz. When VO2 is in the insulating state, the structure acts as a narrow-band absorber, and the absorption at resonance frequencies of 2.54, 2.93 and 3.34 THz is over 95%. In addition, the effect of geometric parameters on the absorption of metamaterial absorber is discussed. Because of the symmetry of the element structure, the absorber is insensitive to the polarization when the electromagnetic wave is vertically incident, and it can keep good absorption performance with the large incident angle. Therefore, the switchable bi-functional metamaterial absorber proposed in this paper can be widely used in terahertz modulation, thermal emitters and electromagnetic energy acquisition, etc.
2022, 15(2): 404-404.
[摘要](102) [HTML全文](53) [PDF 349KB](40)

2022, 15(2): 161-186.   doi: 10.37188/CO.2021-0143

2022, 15(2): 187-209.   doi: 10.37188/CO.EN.2021-0012

Oxide Vertical Cavity Surface Emitting Lasers(VCSELs) are widely used in high-speed optical communications. The reliability of VCSELs is a very important index that requires a high lifetime and low failure rate in the application process. Understanding the root causes and mechanisms of VCSEL failure is necessary and helpful to improve device reliability. In this paper, we summarize and analyze the most common failure modes, causes and mechanisms observed in oxide VCSELs from the perspective of design, manufacturing and application, then apply some appropriate measures and suggestions to prevent or improve them. Moreover, the three dominating factors leading to the failure of VCSELs including oxide layer stress, Electronic Static Discharge (ESD) and humidity corrosion are introduced in more detail. At last, we simply introduce the VCSEL failure cases encountered in the actual accelerated aging verification process. This article can be used as a good VCSEL failure analysis library for chip development and production researchers.

2022, 15(2): 210-223.   doi: 10.37188/CO.2021-0176

2022, 15(1): 1-13.   doi: 10.37188/CO.2021-0115

2021, 14(5): 1039-1055.   doi: 10.37188/CO.2021-0003

2021, 14(5): 1056-1068.   doi: 10.37188/CO.2021-0071

2021, 14(5): 1069-1088.   doi: 10.37188/CO.2021-0044

2021, 14(5): 1089-1103.   doi: 10.37188/CO.2021-0022

2021, 14(5): 1104-1119.   doi: 10.37188/CO.2021-0033

2021, 14(5): 1120-1132.   doi: 10.37188/CO.2021-0125

2021, 14(5): 1133-1145.   doi: 10.37188/CO.2020-0216

2021, 14(5): 1146-1161.   doi: 10.37188/CO.2021-0032

2021, 14(4): 717-735.   doi: 10.37188/CO.2021-0030

2021, 14(4): 736-753.   doi: 10.37188/CO.2021-0095

Exploring topological phases of matter and their exotic physics appeared as a rapidly growing field of study in solid-state electron systems in the past decade. In recent years, there has been a trend on the emulation of topological insulators/semimetals in many other systems, including ultracold quantum gases, trapped ions, photonic, acoustic, mechanical, and electrical circuit systems. Among these platforms, topological circuits made of simple capacitive and inductive circuit elements emerged as a very competitive platform because of its highly controllable degrees of freedom, lowercost, easy implementation, and great flexibility for integration. Owing to the unique advantages of electrical circuits such as arbitrary engineering of long-range hopping, convenient realization of nonlinear, nonreciprocal, and gain effects, highly flexible measurement, many of the nonlinear, non-abelian, and non-Hermitian physics can be potentially realized and investigated using the electrical circuit platform. In this review, we provide the first short overview of the main achievements of topological circuits developed in the past six years, primarily focusing on their theoretical modeling, circuit construction, experimental characterization, and their distinction from their counterparts in quantum electronics and photonics. The scope of this review covers a wide variety of topological circuits, including Hermitian topological circuits hosting nontrivial edge state, higher-order corner state, Weyl particles; higher dimensional topological circuits exhibiting nodal link and nodal knot states; non-Hermitian topological circuits showing skin effects, gain and loss induced nontrivial edge state; self-induced topological edge state in nonlinear topological circuit; topological circuit having non-Abelian gauge potential.

2021, 14(4): 764-781.   doi: 10.37188/CO.2021-0096

2021, 14(4): 792-811.   doi: 10.37188/CO.2021-0066

In the last two decades, optical vortices carried by twisted light wavefronts have attracted a great deal of interest, providing not only new physical insights into light-matter interactions, but also a transformative platform for boosting optical information capacity. Meanwhile, advances in nanoscience and nanotechnology lead to the emerging field of nanophotonics, offering an unprecedented level of light manipulation via nanostructured materials and devices. Many exciting ideas and concepts come up when optical vortices meet nanophotonic devices. Here, we provide a minireview on recent achievements made in nanophotonics for the generation and detection of optical vortices and some of their applications.

2021, 14(4): 812-822.   doi: 10.37188/CO.2021-0023

2021, 14(4): 831-850.   doi: 10.37188/CO.2021-0014

2021, 14(4): 851-866.   doi: 10.37188/CO.2021-0069

2021, 14(4): 867-885.   doi: 10.37188/CO.2021-0036

ISSN 2095-1531

CN 22-1400/O4

CODEN ZGHUC8