Pub Date : 2018-10-01DOI: 10.1109/MWP.2018.8552907
A. Sebastian, S. Trebaol, P. Besnard
Brillouin gain coefficient is usually evaluated using well-established pump-probe technique. We report a technique based upon the cavity ringdown method that enables to characterize this fundamental parameter directly in a Brillouin laser cavity. Indeed, within a unique experimental setup, material gain, optical cavity parameters and laser properties can be extracted. This method would be particularly suitable for micro-resonator lasers intracavity material Brillouin gain determination.
{"title":"Intracavity Brillouin Gain Characterization","authors":"A. Sebastian, S. Trebaol, P. Besnard","doi":"10.1109/MWP.2018.8552907","DOIUrl":"https://doi.org/10.1109/MWP.2018.8552907","url":null,"abstract":"Brillouin gain coefficient is usually evaluated using well-established pump-probe technique. We report a technique based upon the cavity ringdown method that enables to characterize this fundamental parameter directly in a Brillouin laser cavity. Indeed, within a unique experimental setup, material gain, optical cavity parameters and laser properties can be extracted. This method would be particularly suitable for micro-resonator lasers intracavity material Brillouin gain determination.","PeriodicalId":146799,"journal":{"name":"2018 International Topical Meeting on Microwave Photonics (MWP)","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123387545","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-10-01DOI: 10.1109/MWP.2018.8552920
Steven T. Lipkowitz, T. Horton, V. R. Pagan, T. Murphy
Here we present a technique for realizing an image rejecting radio-over-fiber downconverting link. The system uses one arm of a dual-drive Mach-Zehnder modulator (DD-MZM) to modulate an optical carrier with an RF signal, and the other arm to modulate the carrier with a local oscillator (LO). The resulting output is then sent into an asymmetric Mach-Zehnder interferometer (AMZI) which separates the frequency components above and below the LO into separate output ports. By separately detecting these two outputs and applying the appropriate DC bias to the DD-MZM, we are able to obtain inphase and quadrature photocurrents. By combining these I and Q photocurrents with a 90-degree electrical hybrid, we obtain over 40 dB of image rejection.
{"title":"Microwave image rejection mixing using a Mach-Zehnder electrooptic modulator","authors":"Steven T. Lipkowitz, T. Horton, V. R. Pagan, T. Murphy","doi":"10.1109/MWP.2018.8552920","DOIUrl":"https://doi.org/10.1109/MWP.2018.8552920","url":null,"abstract":"Here we present a technique for realizing an image rejecting radio-over-fiber downconverting link. The system uses one arm of a dual-drive Mach-Zehnder modulator (DD-MZM) to modulate an optical carrier with an RF signal, and the other arm to modulate the carrier with a local oscillator (LO). The resulting output is then sent into an asymmetric Mach-Zehnder interferometer (AMZI) which separates the frequency components above and below the LO into separate output ports. By separately detecting these two outputs and applying the appropriate DC bias to the DD-MZM, we are able to obtain inphase and quadrature photocurrents. By combining these I and Q photocurrents with a 90-degree electrical hybrid, we obtain over 40 dB of image rejection.","PeriodicalId":146799,"journal":{"name":"2018 International Topical Meeting on Microwave Photonics (MWP)","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122987711","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-10-01DOI: 10.1109/MWP.2018.8552900
L. McKay, M. Merklein, A. Choudhary, Yang Liu, B. Eggleton, Micah Jenkins, C. Middleton, A. Cramer, Joseph Devenport, A. Klee, R. DeSalvo, K. Vu, D. Choi, P. Ma, S. Madden
Phase shifters are an important building block of modern RF communications and RADAR systems, with an ever increasing demand to improve the operating bandwidth and to reduce power consumption and footprint. Microwave photonic phase shifters based on stimulated Brillion scattering (SBS) offer tunable and broadband phase shifts, however, their performance has been constrained by the requirement of high Brillouin gain to achieve 360° of phase shift. Here, we demonstrate a 360° broadband phase shifter by combining SBS and RF interference which greatly reduces the required Brillouin gain and thus the required optical power. Using this technique, we are able to enhance the phase shift by more than an order of magnitude, showing bandwidth tunability from 0.1-65 GHz while also being optimized to minimize amplitude variations.
{"title":"Broad-band phase-shifter based on stimulated Brillouin scattering and RF interference","authors":"L. McKay, M. Merklein, A. Choudhary, Yang Liu, B. Eggleton, Micah Jenkins, C. Middleton, A. Cramer, Joseph Devenport, A. Klee, R. DeSalvo, K. Vu, D. Choi, P. Ma, S. Madden","doi":"10.1109/MWP.2018.8552900","DOIUrl":"https://doi.org/10.1109/MWP.2018.8552900","url":null,"abstract":"Phase shifters are an important building block of modern RF communications and RADAR systems, with an ever increasing demand to improve the operating bandwidth and to reduce power consumption and footprint. Microwave photonic phase shifters based on stimulated Brillion scattering (SBS) offer tunable and broadband phase shifts, however, their performance has been constrained by the requirement of high Brillouin gain to achieve 360° of phase shift. Here, we demonstrate a 360° broadband phase shifter by combining SBS and RF interference which greatly reduces the required Brillouin gain and thus the required optical power. Using this technique, we are able to enhance the phase shift by more than an order of magnitude, showing bandwidth tunability from 0.1-65 GHz while also being optimized to minimize amplitude variations.","PeriodicalId":146799,"journal":{"name":"2018 International Topical Meeting on Microwave Photonics (MWP)","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114259523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-10-01DOI: 10.1109/MWP.2018.8552857
Yuya Yamaguchi, A. Kanno, N. Yamamoto, S. Takano, S. Oikawa, A. Otomo, T. Kawanishi
We devised a broadband optical phase modulator using an electro-optic polymer material, which is lucrative for its potential for application as the material used in high-speed modulator. It has the possibility to achieve low half-wave voltage and large bandwidth simultaneously. The measured 3-dBo bandwidth of the fabricated modulator reached 50 GHz.
{"title":"Broadband Optical Phase Modulator Based on Electro-Optic Polymer","authors":"Yuya Yamaguchi, A. Kanno, N. Yamamoto, S. Takano, S. Oikawa, A. Otomo, T. Kawanishi","doi":"10.1109/MWP.2018.8552857","DOIUrl":"https://doi.org/10.1109/MWP.2018.8552857","url":null,"abstract":"We devised a broadband optical phase modulator using an electro-optic polymer material, which is lucrative for its potential for application as the material used in high-speed modulator. It has the possibility to achieve low half-wave voltage and large bandwidth simultaneously. The measured 3-dBo bandwidth of the fabricated modulator reached 50 GHz.","PeriodicalId":146799,"journal":{"name":"2018 International Topical Meeting on Microwave Photonics (MWP)","volume":"214 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114363300","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-10-01DOI: 10.1109/MWP.2018.8552894
Shun Liu, Chaitanya K. Mididoddi, Huiyu Zhou, Baojun Li, Weichao Xu, Chao Wang
Real-time detection of high-frequency RF signals requires sophisticated hardware with large bandwidth and high sampling rates. Existing microwave photonic methods have enabled sub-Nyquist sampling for bandwidth-efficient RF signal detection but fall short in single-shot reconstruction. Here we report a novel single-shot sub-Nyquist RF signal detection method based on a trained deep neural network. In a proof-of-concept demonstration, our system successfully reconstructs high frequency multi-toned RF signals from 5x down-sampled singleshot measurements by utilizing a deep convolutional neural network. The presented approach is a powerful digital accelerator to existing hardware detectors to significantly enhance the detection capability.
{"title":"Single-Shot Sub-Nyquist RF Signal Reconstruction Based on Deep Learning Network","authors":"Shun Liu, Chaitanya K. Mididoddi, Huiyu Zhou, Baojun Li, Weichao Xu, Chao Wang","doi":"10.1109/MWP.2018.8552894","DOIUrl":"https://doi.org/10.1109/MWP.2018.8552894","url":null,"abstract":"Real-time detection of high-frequency RF signals requires sophisticated hardware with large bandwidth and high sampling rates. Existing microwave photonic methods have enabled sub-Nyquist sampling for bandwidth-efficient RF signal detection but fall short in single-shot reconstruction. Here we report a novel single-shot sub-Nyquist RF signal detection method based on a trained deep neural network. In a proof-of-concept demonstration, our system successfully reconstructs high frequency multi-toned RF signals from 5x down-sampled singleshot measurements by utilizing a deep convolutional neural network. The presented approach is a powerful digital accelerator to existing hardware detectors to significantly enhance the detection capability.","PeriodicalId":146799,"journal":{"name":"2018 International Topical Meeting on Microwave Photonics (MWP)","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133793301","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-10-01DOI: 10.1109/MWP.2018.8552877
A. Mahendra, E. Magi, A. Choudhary, Yang Liu, D. Marpaung, B. Eggleton
We present a high-performance, low-noise figure tunable microwave photonic bandpass filter based on stimulated Brillouin scattering (SBS) loss responses. The bandpass filter response is formed by suppressing the out-of-band signal using multiple broadened SBS loss responses on a high-performance MWP link without introducing additional noise in the passband. A noise figure of 20 dB and -17 dB link gain of 100 MHz passband bandwidth at 14 GHz with spurious free dynamic range of 105 dB.Hz$^{2/3}$ are obtained. Multi-bandpass response, bandwidth reconfigurability from 100 MHz to 1 GHz and center frequency tunability up to 16 GHz are also demonstrated.
{"title":"High Performance, Low Noise Figure Brillouin-based Tunable Microwave Photonic Bandpass Filter","authors":"A. Mahendra, E. Magi, A. Choudhary, Yang Liu, D. Marpaung, B. Eggleton","doi":"10.1109/MWP.2018.8552877","DOIUrl":"https://doi.org/10.1109/MWP.2018.8552877","url":null,"abstract":"We present a high-performance, low-noise figure tunable microwave photonic bandpass filter based on stimulated Brillouin scattering (SBS) loss responses. The bandpass filter response is formed by suppressing the out-of-band signal using multiple broadened SBS loss responses on a high-performance MWP link without introducing additional noise in the passband. A noise figure of 20 dB and -17 dB link gain of 100 MHz passband bandwidth at 14 GHz with spurious free dynamic range of 105 dB.Hz$^{2/3}$ are obtained. Multi-bandpass response, bandwidth reconfigurability from 100 MHz to 1 GHz and center frequency tunability up to 16 GHz are also demonstrated.","PeriodicalId":146799,"journal":{"name":"2018 International Topical Meeting on Microwave Photonics (MWP)","volume":"118 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132391229","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-10-01DOI: 10.1109/MWP.2018.8552848
J. Panasiewicz, Britto Larissa A. D., G. M. Pacheco, A. Rissons, F. Destic
This article presents a photonic circuit that achieves direct carrier QPSK modulation of an RF signal from an opto-electronic oscillator (OEO) suitable for satellite data transmitter. The circuit was implemented with three Mach-Zehnder optical modulators. One modulator was used to construct an OEO to generate a carrier with a frequency equal to 2.019 GHz. The others two modulators were used to compose the microwave photonic I/Q modulator. The setup initially achieved a data rate of 50 Mbps in a QPSK scheme with an EVM of 7.5%. Using a root-raised-cosine filter, it was possible to reduce the EVM to 5%. The diagrams of the optoelectronic circuit and the modulation measurements are displayed. After the EVM analysis, the modulated signal was demodulated through an actual satellite receiver. Using the demodulator, it was possible to measure the BER and consequently the degradation analysis. The degradation for a bit rate of 100 Mbps was 0.07 dB using the OEO as RF generator. In this case, the values of Eb/N0 and BER were 11.37 dB and 10-7, respectively.
{"title":"A photonic QPSK modulation in 2 GHz with an RF signal from a microwave optoelectronic oscillator","authors":"J. Panasiewicz, Britto Larissa A. D., G. M. Pacheco, A. Rissons, F. Destic","doi":"10.1109/MWP.2018.8552848","DOIUrl":"https://doi.org/10.1109/MWP.2018.8552848","url":null,"abstract":"This article presents a photonic circuit that achieves direct carrier QPSK modulation of an RF signal from an opto-electronic oscillator (OEO) suitable for satellite data transmitter. The circuit was implemented with three Mach-Zehnder optical modulators. One modulator was used to construct an OEO to generate a carrier with a frequency equal to 2.019 GHz. The others two modulators were used to compose the microwave photonic I/Q modulator. The setup initially achieved a data rate of 50 Mbps in a QPSK scheme with an EVM of 7.5%. Using a root-raised-cosine filter, it was possible to reduce the EVM to 5%. The diagrams of the optoelectronic circuit and the modulation measurements are displayed. After the EVM analysis, the modulated signal was demodulated through an actual satellite receiver. Using the demodulator, it was possible to measure the BER and consequently the degradation analysis. The degradation for a bit rate of 100 Mbps was 0.07 dB using the OEO as RF generator. In this case, the values of Eb/N0 and BER were 11.37 dB and 10-7, respectively.","PeriodicalId":146799,"journal":{"name":"2018 International Topical Meeting on Microwave Photonics (MWP)","volume":"73 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129160199","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-10-01DOI: 10.1109/MWP.2018.8552875
D. Munk, M. Katzman, Mirit Hen, M. Priel, A. Bergman, A. Zadok, Y. Kaganovskii, M. Rosenbluh, Naor Inbar, Menachem Vofsy
We propose and demonstrate an integrated 8-channel dense wavelength division multiplexer in silicon-on-insulator platform. The device layout comprises of 7 stages in a tree topology. Each stage is based on an unbalanced Mach-Zehnder interferometer with a nested ring resonator. The transfer function of each stage is that of an auto-regressive moving-average filter, characterized by a uniform passband, strong out-of-band rejection and sharp spectral transitions. The passband of each channel is extremely narrow: only 0.135 nm (16 GHz), and the worst-case crosstalk among channels is -22 dB. Individual phase delays within the device are trimmed through selective photo-removal of an upper cladding layer of photo-sensitive chalcogenide glass. The devices are suitable for integrated-photonic processing of radio-over-fiber and mm-wave communication.
{"title":"Silicon-Photonic Dense 8-Channel Multiplexer Using Auto-Regressive Moving-Average Filters","authors":"D. Munk, M. Katzman, Mirit Hen, M. Priel, A. Bergman, A. Zadok, Y. Kaganovskii, M. Rosenbluh, Naor Inbar, Menachem Vofsy","doi":"10.1109/MWP.2018.8552875","DOIUrl":"https://doi.org/10.1109/MWP.2018.8552875","url":null,"abstract":"We propose and demonstrate an integrated 8-channel dense wavelength division multiplexer in silicon-on-insulator platform. The device layout comprises of 7 stages in a tree topology. Each stage is based on an unbalanced Mach-Zehnder interferometer with a nested ring resonator. The transfer function of each stage is that of an auto-regressive moving-average filter, characterized by a uniform passband, strong out-of-band rejection and sharp spectral transitions. The passband of each channel is extremely narrow: only 0.135 nm (16 GHz), and the worst-case crosstalk among channels is -22 dB. Individual phase delays within the device are trimmed through selective photo-removal of an upper cladding layer of photo-sensitive chalcogenide glass. The devices are suitable for integrated-photonic processing of radio-over-fiber and mm-wave communication.","PeriodicalId":146799,"journal":{"name":"2018 International Topical Meeting on Microwave Photonics (MWP)","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128018174","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-10-01DOI: 10.1109/MWP.2018.8552844
Noor Hamdash, A. Sharaiha, T. Rampone, P. Morel, D. Le Berre, N. Martin, C. Quendo
This paper investigates the performance differences obtained by using four different SOAs as microwave phase shifters. All performances are evaluated in terms of measured phase shift, radiofrequency gain penalty and 3 dB bandwidth. A microwave phase shift as high as 89.3° is achieved by slow and fast light effects in a high gain extra-nonlinear SOA. In the same SOA a different response of the phase from usual CPO is observed experimentally at low frequencies for particular operating points in saturated regime. This phenomenon is theoretically analyzed by means of a small-signal analysis.
{"title":"Experimental and Small-signal Analysis of Microwave Photonic Phase Shifter based on Slow and Fast Light using Linear and Nonlinear Semiconductor Optical Amplifiers","authors":"Noor Hamdash, A. Sharaiha, T. Rampone, P. Morel, D. Le Berre, N. Martin, C. Quendo","doi":"10.1109/MWP.2018.8552844","DOIUrl":"https://doi.org/10.1109/MWP.2018.8552844","url":null,"abstract":"This paper investigates the performance differences obtained by using four different SOAs as microwave phase shifters. All performances are evaluated in terms of measured phase shift, radiofrequency gain penalty and 3 dB bandwidth. A microwave phase shift as high as 89.3° is achieved by slow and fast light effects in a high gain extra-nonlinear SOA. In the same SOA a different response of the phase from usual CPO is observed experimentally at low frequencies for particular operating points in saturated regime. This phenomenon is theoretically analyzed by means of a small-signal analysis.","PeriodicalId":146799,"journal":{"name":"2018 International Topical Meeting on Microwave Photonics (MWP)","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128458436","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-10-01DOI: 10.1109/MWP.2018.8552851
Pedro Tovar, Luis E. Ynoquio H, J. P. Weid, Vladimir B. RJabulkaibeiro, R. Ribeiro
This paper reports the photonic generation of apodized non-linear frequency modulation (NLFM) microwave pulses by using a self-heterodyne scheme. Time-resolved optical spectroscopy was developed for the characterization of the laser diode chirp. By using a step-shaped current stimulus the laser chirp transfer function H(s) was obtained.With knowledge of H(s), a numerical model produced the suitable current stimulus i(t) needed to generate apodized-shaped radio frequency chirped pulses through self-heterodyning. Experiment results agreed with the numerical simulations.
{"title":"Time-Resolved spectroscopy for laser chirp characterization and self-heterodyne generation of apodized-NLFM microwave pulses","authors":"Pedro Tovar, Luis E. Ynoquio H, J. P. Weid, Vladimir B. RJabulkaibeiro, R. Ribeiro","doi":"10.1109/MWP.2018.8552851","DOIUrl":"https://doi.org/10.1109/MWP.2018.8552851","url":null,"abstract":"This paper reports the photonic generation of apodized non-linear frequency modulation (NLFM) microwave pulses by using a self-heterodyne scheme. Time-resolved optical spectroscopy was developed for the characterization of the laser diode chirp. By using a step-shaped current stimulus the laser chirp transfer function H(s) was obtained.With knowledge of H(s), a numerical model produced the suitable current stimulus i(t) needed to generate apodized-shaped radio frequency chirped pulses through self-heterodyning. Experiment results agreed with the numerical simulations.","PeriodicalId":146799,"journal":{"name":"2018 International Topical Meeting on Microwave Photonics (MWP)","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123544884","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：