Topmetal-M2 is a large-area pixel sensor chip fabricated using the GSMC 130 nm CMOS process in 2021.The pixel array of Topmetal-M2 consists of pixels of 400 rows×512 columns with a pixel pitch of 45μm×45μm...Topmetal-M2 is a large-area pixel sensor chip fabricated using the GSMC 130 nm CMOS process in 2021.The pixel array of Topmetal-M2 consists of pixels of 400 rows×512 columns with a pixel pitch of 45μm×45μm.The array is divided into 16 subarrays,with pixels of 400 rows×32 columns per subarray.Each pixel incorporates two charge sensors:a diode sensor and a Topmetal sensor.The in-pixel circuit primarily consists of a charge-sensitive amplifier for energy measurements,a discriminator with a peak-holding circuit,and a time-to-amplitude converter for time-of-arrival measurements.The pixel of Topmetal-M2 has a charge input range of~0-3 k e-,a voltage output range of~0-180 mV,and a charge-voltage conversion gain of~59.56μV∕e-.The average equivalent noise charge of Topmetal-M2,which includes the readout electronic system noise,is~43.45 e-.In the scanning mode,the time resolution of Topmetal-M2 is 1 LSB=1.25μs,and the precision is^()7.41μs.At an operating voltage of 1.5 V,Topmetal-M2 has a power consumption of~49 mW∕cm~2.In this article,we provide a comprehensive overview of the chip architecture,pixel working principles,and functional behavior of Topmetal-M2.Furthermore,we present the results of preliminary tests conducted on Topmetal-M2,namely,alpha-particle and soft X-ray tests.展开更多
The cavity enhanced absorption technique is applied to N2O detection around 2.86 μm using a continuous-wave color center laser. A high-finesse triangular ring cavity is used in this technology. Transmission through t...The cavity enhanced absorption technique is applied to N2O detection around 2.86 μm using a continuous-wave color center laser. A high-finesse triangular ring cavity is used in this technology. Transmission through the cavity is obtained by jittering the cavity-length with a piezo on one of the cavity mirrors. A minimum detectable absorption coefficient of 2 × 10-6 cm-1 is achieved with a mirror reflectivity of 99.24%, corresponding to a N2O detection limit of 600 parts per billion.展开更多
The gas-sensitive film coated π-phase-shifted long-period fiber grating(LPFG),consisting of two same long-period fiber gratings cascaded by a regular fiber with length of half of the grating period,is proposed for ga...The gas-sensitive film coated π-phase-shifted long-period fiber grating(LPFG),consisting of two same long-period fiber gratings cascaded by a regular fiber with length of half of the grating period,is proposed for gas sensing.The sensitivity of the sensor is defined by the change rate of the transmission at specific wavelength with respect to the film refractive index.The qualitative and numerical analyses show that to get a high sensitivity,the optimal coupling strength of each long-period fiber grating is √2 π/4.With this coupling strength,the longer the grating is,the higher sensitivity the sensor has.By choosing appropriate grating period,a high sensitivity for the film with a certain refractive index and thickness can be attained.展开更多
Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution （QKD） system. A new idea is put up to desi...Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution （QKD） system. A new idea is put up to design a quick single-photon detector. This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes （APDs）. All of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal. The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector. The single-photon prompt detection can come true for high repetition-rate pulses. The applying of this detector will largely raise the code rate of the OKD. and boost the commercial use.展开更多
Background The Gas Pixel Detector(GPD)is a key part of the Polarimetry Focusing Array(PFA)sub-system onboard the enhance X-ray Timing and Polarimetry mission(eXTP).The GPD can accurately provide the polarized angle an...Background The Gas Pixel Detector(GPD)is a key part of the Polarimetry Focusing Array(PFA)sub-system onboard the enhance X-ray Timing and Polarimetry mission(eXTP).The GPD can accurately provide the polarized angle and degree for incoming soft X-rays(requirements of minimum detectable polarization<1%(10^(6) s,1 mCrab))from celestial objects under extreme conditions of density,gravity and magnetism.Purpose Paste the GPD chips on a matched ceramic package is one of the most important procedures for the GPD assembly,and the parallelism between the top surface of an ASIC chip and the bottom surface of a Gas Electron Multiplier(GEM)foil can have impact on the distribution of electric field within transfer region and reconstruction of photoelectric trajectories,resulting in deterioration of the GPD sensitivity.This study quantifies the influence and gives a reasonable expectation of the parallelism.Methods A simulation framework of the GPD is constructed to quantify the influence on the GPD performance and values of the parallelism are measured by a gauge with a position resolution of o.1μm.Results:The difference of degree of modulation is less than 1% comparing the parallelism with a value of 20μm to a value of 0μm in response to both polarized and unpolarized X-rays.Meanwhile,the value of parallelism can reach 6.9±3.4μm(0.0176°±0.0087°)by testing and verifying.Conclusions The impact on the GPD performance can be less than 1%as the parallelism with an order of 20μm,and we also give a reasonable measuring method and verify the controllability and feasibility of the parallelism with an order of 20μm for pasting the ASIC chip on the surface of a ceramic package.展开更多
An external-cavity diode laser (ECDL) has been used to investigate pressure-induced self-broadening as well as frequency shift of 2v3 band R9 manifold of methane. A phase sensitivity detection technology has been empl...An external-cavity diode laser (ECDL) has been used to investigate pressure-induced self-broadening as well as frequency shift of 2v3 band R9 manifold of methane. A phase sensitivity detection technology has been employed to determine the pressure induced frequency shift coefficient, however, which is obtained by line shape analyses of the recorded absorption spectrum. F1 and F2 unresolved double lines near 6105.626 cm-1 were measured as an object because they are often used to the high sensitivity detection of trace methane. The results show that the self-broadening and pressure induced frequency shift coefficients are 0.0232±0.003 and 0.0055± 0.0007 MHz/Pa, respectively.展开更多
基金supported by the National Key Research and Development Program of China(No.2020YFE0202002)the National Natural Science Foundation of China(Nos.11875146 and U1932143)。
文摘Topmetal-M2 is a large-area pixel sensor chip fabricated using the GSMC 130 nm CMOS process in 2021.The pixel array of Topmetal-M2 consists of pixels of 400 rows×512 columns with a pixel pitch of 45μm×45μm.The array is divided into 16 subarrays,with pixels of 400 rows×32 columns per subarray.Each pixel incorporates two charge sensors:a diode sensor and a Topmetal sensor.The in-pixel circuit primarily consists of a charge-sensitive amplifier for energy measurements,a discriminator with a peak-holding circuit,and a time-to-amplitude converter for time-of-arrival measurements.The pixel of Topmetal-M2 has a charge input range of~0-3 k e-,a voltage output range of~0-180 mV,and a charge-voltage conversion gain of~59.56μV∕e-.The average equivalent noise charge of Topmetal-M2,which includes the readout electronic system noise,is~43.45 e-.In the scanning mode,the time resolution of Topmetal-M2 is 1 LSB=1.25μs,and the precision is^()7.41μs.At an operating voltage of 1.5 V,Topmetal-M2 has a power consumption of~49 mW∕cm~2.In this article,we provide a comprehensive overview of the chip architecture,pixel working principles,and functional behavior of Topmetal-M2.Furthermore,we present the results of preliminary tests conducted on Topmetal-M2,namely,alpha-particle and soft X-ray tests.
基金This work was supported by the Doctoral Scientific Research Fund of Education Ministry of China(1999014106)
文摘The cavity enhanced absorption technique is applied to N2O detection around 2.86 μm using a continuous-wave color center laser. A high-finesse triangular ring cavity is used in this technology. Transmission through the cavity is obtained by jittering the cavity-length with a piezo on one of the cavity mirrors. A minimum detectable absorption coefficient of 2 × 10-6 cm-1 is achieved with a mirror reflectivity of 99.24%, corresponding to a N2O detection limit of 600 parts per billion.
基金supported by the National Natural Science Foundation of China (No.60777035)the Scientific Research Key Project Fund of the Ministry of Education (No.208040)the Shanghai Leading Academic Discipline Project (No.T0501)
文摘The gas-sensitive film coated π-phase-shifted long-period fiber grating(LPFG),consisting of two same long-period fiber gratings cascaded by a regular fiber with length of half of the grating period,is proposed for gas sensing.The sensitivity of the sensor is defined by the change rate of the transmission at specific wavelength with respect to the film refractive index.The qualitative and numerical analyses show that to get a high sensitivity,the optimal coupling strength of each long-period fiber grating is √2 π/4.With this coupling strength,the longer the grating is,the higher sensitivity the sensor has.By choosing appropriate grating period,a high sensitivity for the film with a certain refractive index and thickness can be attained.
基金the National Natu-ral Science Foundation of China (No.60378011 and 60578043)the Beijing Municipal Education Com-mission (No.XK100130637).
文摘Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution （QKD） system. A new idea is put up to design a quick single-photon detector. This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes （APDs）. All of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal. The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector. The single-photon prompt detection can come true for high repetition-rate pulses. The applying of this detector will largely raise the code rate of the OKD. and boost the commercial use.
基金supported by the Strategic Priority Program on Space Science,the Chinese Academy of Sciences,Grant No.XDA15020500,XDA15020501,XDA15020501-02.
文摘Background The Gas Pixel Detector(GPD)is a key part of the Polarimetry Focusing Array(PFA)sub-system onboard the enhance X-ray Timing and Polarimetry mission(eXTP).The GPD can accurately provide the polarized angle and degree for incoming soft X-rays(requirements of minimum detectable polarization<1%(10^(6) s,1 mCrab))from celestial objects under extreme conditions of density,gravity and magnetism.Purpose Paste the GPD chips on a matched ceramic package is one of the most important procedures for the GPD assembly,and the parallelism between the top surface of an ASIC chip and the bottom surface of a Gas Electron Multiplier(GEM)foil can have impact on the distribution of electric field within transfer region and reconstruction of photoelectric trajectories,resulting in deterioration of the GPD sensitivity.This study quantifies the influence and gives a reasonable expectation of the parallelism.Methods A simulation framework of the GPD is constructed to quantify the influence on the GPD performance and values of the parallelism are measured by a gauge with a position resolution of o.1μm.Results:The difference of degree of modulation is less than 1% comparing the parallelism with a value of 20μm to a value of 0μm in response to both polarized and unpolarized X-rays.Meanwhile,the value of parallelism can reach 6.9±3.4μm(0.0176°±0.0087°)by testing and verifying.Conclusions The impact on the GPD performance can be less than 1%as the parallelism with an order of 20μm,and we also give a reasonable measuring method and verify the controllability and feasibility of the parallelism with an order of 20μm for pasting the ASIC chip on the surface of a ceramic package.
基金This work was partially supported by Excellent experts funds of development-plan council of Shanxi province and the Natural Science Funds of Shanxi province (No.20041037).
文摘An external-cavity diode laser (ECDL) has been used to investigate pressure-induced self-broadening as well as frequency shift of 2v3 band R9 manifold of methane. A phase sensitivity detection technology has been employed to determine the pressure induced frequency shift coefficient, however, which is obtained by line shape analyses of the recorded absorption spectrum. F1 and F2 unresolved double lines near 6105.626 cm-1 were measured as an object because they are often used to the high sensitivity detection of trace methane. The results show that the self-broadening and pressure induced frequency shift coefficients are 0.0232±0.003 and 0.0055± 0.0007 MHz/Pa, respectively.
