A new photonic scheme for various waveforms generation has been proposed and demonstrated. In the scheme, two cascaded single-drive LiNbO Mach-Zehnder modulators serve as pulse shaper and the polarization-dependent character of the modulators is fully exploited and utilized. By arranging the polarization states of the incident light, two different spectra are achieved on two orthogonal polarization components respectively. Finally, the desired waveforms can be obtained by superimposing the photocurrents of the two orthogonal signals on a photodetector. The detailed theoretical analyses and simulations are given. In the experiment, square-shaped waveform, triangular waveform and sawtooth (or reversed-sawtooth) waveform are obtained successfully. Furthermore, an approach to smoothing the sawtooth waveform with fewer harmonics is suggested and verified.
This paper introduces a novel web‐based virtual laboratory to assist teaching of Sensitive High Resolution Ion Micro‐probe (SHRIMP) implementation, called SHRIMP VL. This virtual laboratory is especially designed to aid learning of the instrument operation procedure. SHRIMP VL was developed based on hypertext preprocessor (PHP) technology and the Browser/Server application model, combined with the Yii framework and database technology. The virtual lab includes a virtual experiment platform to simulate the experiment procedure of the actual instrument and show experiment results. It also provides an immersive and visible virtual environment with navigational hints to guide user learning of the experiment operation, as well as theory presentations. To evaluate this virtual laboratory, two questionnaires were provided to students, who reported that SHRIMP VL is effective in helping them understand and master the instrument and experimental procedures, thereby improving their learning efficiency and laying foundations for personal operation of on‐site instruments.
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