Ultrahigh spatiotemporal resolution beam signal reconstruction with bunch phase compensation

Various electromagnetic signals are excited by the beam in the acceleration and beam-diagnostic elements of a particle accelerator.It is important to obtain time-domain waveforms of these signals with high temporal resolution for research,such as the study of beam–cavity interactions and bunch-by-bunch parameter measurements.Therefore,a signal reconstruction algorithm with ultrahigh spatiotemporal resolution and bunch phase compensation based on equivalent sampling is proposed in this paper.Compared with traditional equivalent sampling,the use of phase compensation and setting the bunch signal zero-crossing point as the time reference can construct a more accurate reconstructed signal.The basic principles of the method,simulation,and experimental comparison are also introduced.Based on the beam test platform of the Shanghai Synchrotron Radiation Facility(SSRF)and the method of experimental verification,the factors that affect the reconstructed signal quality are analyzed and discussed,including the depth of the sampled data,quantization noise of analog-to-digital converter,beam transverse oscillation,and longitudinal oscillation.The results of the beam experiments show that under the user operation conditions of the SSRF,a beam excitation signal with an amplitude uncertainty of 2%can be reconstructed.

Pulse reference-based compensation technique for intensity-modulated optical fiber sensors

We propose a compensation technique based on pulse reference for intensity-modulated optical fiber sensors that can compensate the power fluctuation of the light source, the change of optical components transmission loss, and the coupler splitting ratio. The theoretical principle of this compensation technique is analyzed and a temperature sensor based on fiber coating-covered optical microfiber is carried out to demonstrate the compensation effect. The system noise is measured to be 0.0005 dB with the temperature sensitivity reaching -0.063 dB/℃, and the output drift is 0.006 dB in 2 h at room temperature. The output shows a slight variation （0.0061 dB） when the light source and the common liKht path suffer a 3 dB attenuation fluctuation.

Semi-Empirical, Multi-Wavelength Raman Gain Engineering Algorithm with Pump Interaction Compensation Technique

We propose a simple algorithm for the precise engineering of multi-channel gain profile of Raman amplifier. By employing a linear approximation in the pump interaction calculation, together with a semi-empirical pump power correction using the simplistic output signal spectrum measurement, excellent gain engineering capability has been demonstrated for various target gain profiles, within +/- 0.4dB of error.

Low-noise and highly stable optical fiber temperature sensor using modified pulse-reference-based compensation technique

We modify the pulse-reference-based compensation technique and propose a low-noise and highly stable optical fiber temperature sensor based on a zinc telluride film-coated fiber tip. The system noise is measured to be 0.0005 dB, which makes it possible for the detection of the minor reflectivity change of the film at different temperatures. The temperature sensitivity is 0.0034 d B/℃, so the resolution can achieve 0.2℃. The maximum difference of the temperature output values of the sensor at 20℃ at different points in time is 0.39℃. The low cost, ultra-small size, high stability, and good repeatability of the sensor make it a promising temperature sensing device for practical application.

A 12-bit,40-Ms/s pipelined ADC with an improved operational amplifier

This paper proposes a 12-bit,40-Ms/s pipelined analog-to-digital converter（ADC） with an improved high-gain and wide-bandwidth operational amplifier（opamp）.Based on the architecture of the proposed ADC,the non-ideal factors of opamps are first analyzed,which have the significant impact on the ADC＇s resolution.Then,the compensation techniques of the ADC＇s opamp are presented to restrain the negative effect introduced by the gainboosting technique and switched-capacitor common-mode-feedback structure.After analysis and optimization,the ADC implemented in a 0.35μm standard CMOS process shows a maximum signal-to-noise distortion ratio of 60.5 dB and a spurious-free dynamic range of 74.5 dB,respectively,at a 40 MHz sample clock with over 2 Vpp input range.