We report a low-noise, high-signal-to-noise-ratio(SNR) balanced homodyne detector based on the standard transimpedance amplifier circuit and the inductance and capacitance combination for the measurement of the bright...We report a low-noise, high-signal-to-noise-ratio(SNR) balanced homodyne detector based on the standard transimpedance amplifier circuit and the inductance and capacitance combination for the measurement of the bright squeezed state in the range from 1 kHz to 100 kHz. A capacitance is mounted at the input end of the AC branch to prevent the DC photocurrent from entering the AC branch and avoid AC branch saturation. By adding a switch at the DC branch,the DC branch can be flexibly turned on and off on different occasions. When the switch is on, the DC output provides a monitor signal for laser beam alignment. When the switch is off, the electronic noise of the AC branch is greatly reduced at audio-frequency band due to immunity to the impedance of the DC branch, hence the SNR of the AC branch is significantly improved. As a result, the electronic noise of the AC branch is close to -125 dBm, and the maximum SNR of the AC branch is 48 dB with the incident power of 8 mW in the range from 1 kHz to 100 kHz. The developed photodetector paves a path for measuring the bright squeezed state at audio-frequency band.展开更多
N400 is an objective electrophysiological index in semantic processing for brain.This study focuses on the sensitivity of N400 effect during speech comprehension under the uni-and bi-modality conditions.Varying the Si...N400 is an objective electrophysiological index in semantic processing for brain.This study focuses on the sensitivity of N400 effect during speech comprehension under the uni-and bi-modality conditions.Varying the Signal-to-Noise Ratio(SNR) of speech signal under the conditions of Audio-only(A),Visual-only(V,i.e.,lip-reading),and Audio-Visual(AV),the semantic priming paradigm is used to evoke N400 effect and measure the speech recognition rate.For the conditions A and high SNR AV,the N400 amplitudes in the central region are larger;for the conditions of V and low SNR AV,the N400 amplitudes in the left-frontal region are larger.The N400 amplitudes of frontal and central regions under the conditions of A,AV,and V are consistent with speech recognition rate of behavioral results.These results indicate that audio-cognition is better than visual-cognition at high SNR,and visual-cognition is better than audio-cognition at low SNR.展开更多
We demonstrated a continuous wave(cw) single-frequency intracavity frequency-doubled Nd:YVO_4/LBO laser with 532 nm output of 7.5 W and 1.06 μm output of 3.1 W, and low intensity noise in audio frequency region.To su...We demonstrated a continuous wave(cw) single-frequency intracavity frequency-doubled Nd:YVO_4/LBO laser with 532 nm output of 7.5 W and 1.06 μm output of 3.1 W, and low intensity noise in audio frequency region.To suppress the intensity noise of the high power 532 nm laser, a laser frequency locking system and a feedback loop based on a Mach-Zehnder interferometer were designed and used.The influences of the frequency stabilization and the crucial parameters of the MZI, such as the power splitting ratio of the beam splitters and the locking state of the MZI, on the intensity noise of the 532 nm laser were investigated in detail.After the experimental optimizations, the laser intensity noise in the frequency region from 0.4 kHz to 10 kHz was significantly suppressed.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11654002,61575114,11874250,and 11804207)the National Key Research and Development Program of China(Grant No.2016YFA0301401)+3 种基金the Program for Sanjin Scholar of Shanxi Province,Chinathe Program for Outstanding Innovative Teams of Higher Learning Institutions of Shanxi,Chinathe Fund for Shanxi“1331 Project”Key Subjects Construction,ChinaKey Research and Development Projects of Shanxi Province,China(Grant No.201903D111001)。
文摘We report a low-noise, high-signal-to-noise-ratio(SNR) balanced homodyne detector based on the standard transimpedance amplifier circuit and the inductance and capacitance combination for the measurement of the bright squeezed state in the range from 1 kHz to 100 kHz. A capacitance is mounted at the input end of the AC branch to prevent the DC photocurrent from entering the AC branch and avoid AC branch saturation. By adding a switch at the DC branch,the DC branch can be flexibly turned on and off on different occasions. When the switch is on, the DC output provides a monitor signal for laser beam alignment. When the switch is off, the electronic noise of the AC branch is greatly reduced at audio-frequency band due to immunity to the impedance of the DC branch, hence the SNR of the AC branch is significantly improved. As a result, the electronic noise of the AC branch is close to -125 dBm, and the maximum SNR of the AC branch is 48 dB with the incident power of 8 mW in the range from 1 kHz to 100 kHz. The developed photodetector paves a path for measuring the bright squeezed state at audio-frequency band.
基金supported by the National Natural Science Foundation of China (Nos. 61601028 and 61431007)the Key R&D Program of Guangdong Province of China (No.2018B030339001)the National Key R&D Program of China (No. 2017YFB1002505)。
文摘N400 is an objective electrophysiological index in semantic processing for brain.This study focuses on the sensitivity of N400 effect during speech comprehension under the uni-and bi-modality conditions.Varying the Signal-to-Noise Ratio(SNR) of speech signal under the conditions of Audio-only(A),Visual-only(V,i.e.,lip-reading),and Audio-Visual(AV),the semantic priming paradigm is used to evoke N400 effect and measure the speech recognition rate.For the conditions A and high SNR AV,the N400 amplitudes in the central region are larger;for the conditions of V and low SNR AV,the N400 amplitudes in the left-frontal region are larger.The N400 amplitudes of frontal and central regions under the conditions of A,AV,and V are consistent with speech recognition rate of behavioral results.These results indicate that audio-cognition is better than visual-cognition at high SNR,and visual-cognition is better than audio-cognition at low SNR.
基金Project supported by the National Key R&D Program of China(Grant No.2016YFA0301401)
文摘We demonstrated a continuous wave(cw) single-frequency intracavity frequency-doubled Nd:YVO_4/LBO laser with 532 nm output of 7.5 W and 1.06 μm output of 3.1 W, and low intensity noise in audio frequency region.To suppress the intensity noise of the high power 532 nm laser, a laser frequency locking system and a feedback loop based on a Mach-Zehnder interferometer were designed and used.The influences of the frequency stabilization and the crucial parameters of the MZI, such as the power splitting ratio of the beam splitters and the locking state of the MZI, on the intensity noise of the 532 nm laser were investigated in detail.After the experimental optimizations, the laser intensity noise in the frequency region from 0.4 kHz to 10 kHz was significantly suppressed.
