A novel thin-film lithium niobate (TFLN) electro-optic modulator is proposed and demonstrated. LiNbO3-silica hybrid waveguide is adopted to maintain low o

A novel thin-film lithium niobate (TFLN) electro-optic modulator is proposed and demonstrated. LiNbO3-silica hybrid waveguide is adopted to maintain low optical loss for an electrode spacing as narrow as 3 µm, resulting in a low half-wave-voltage length product of only 1.7 V·cm. Capacitively loaded traveling-wave electrodes (CL-TWEs) are employed to reduce the microwave loss, while quartz substrate is used in place of silicon substrate to achieve velocity matching. The fabricated TFLN modulator with a 5-mm-long modulation region exhibits a half-wave-voltage of 3.4 V and merely less than 2 dB roll-off in electro-optic response up to 67 GHz. show less

At the mirrors of a Laser-Diode Self-Mixing Interferometer, the output beams carry anti-correlated (i.e., in phase opposition) interferometric signals, wh

At the mirrors of a Laser-Diode Self-Mixing Interferometer, the output beams carry anti-correlated (i.e., in phase opposition) interferometric signals, whereas the superposed noise fluctuations are (partially) correlated. Therefore, by using as an instrumental output of the interferometer the difference of the two, we double the amplitude of the self-mixing useful signal while the superposed noise is reduced. To validate the idea, we first calculate the noise reduction by means of a second-quantization model, finding that in a laser diode the SNR can be improved by 8.2-dB, typically. Then, we also carry out an experimental measurement of SNR and find very good agreement with the theoretical result. show less

Microrobots-assisted drug delivery and surgery have been always in the spotlight and are highly anticipated to solve the challenges of cancer in situ trea

Microrobots-assisted drug delivery and surgery have been always in the spotlight and are highly anticipated to solve the challenges of cancer in situ treatment. These versatile small biomedical robots are expected to realize direct access to the tumor or disease site for precise treatment, which requires real-time and high-resolution in vivo tracking as feedback for the microrobots’ actuation and control. Among current biomedical imaging methods, photoacoustic imaging (PAI) is presenting its outstanding performances in the tracking of micro-robots in the human body derived from its great advantages of excellent imaging resolution and contrast in deep tissue. In this review, we summarize the PAI techniques, imaging systems, and their biomedical applications in microrobots tracking in vitro and in vivo. From a robotic tracking perspective, we also provide some insight into the future of photoacoustic imaging technology in clinical applications.show less

In this article, taking advantage of the special magnetic shieldings and the optimal coil design of a transportable rubidium atomic fountain clock, the in

In this article, taking advantage of the special magnetic shieldings and the optimal coil design of a transportable rubidium atomic fountain clock, the intensity distribution in space and the fluctuations with time of the quantization magnetic field in Ramsey region were measured using the atomic magneton-sensitive transition method. In an approximately 310 mm length of the Ramsey region, a peak to peak magnetic field intensity of a 0.74 nT deviation in space and a 0.06 nT fluctuation with time were obtained. These results correspond to a second-order Zeeman frequency shift of approximately (2095±5.1）×10^-17. This is an essential step in advancing the total frequency uncertainty of the fountain clock to the order of 10⁻¹⁷. show less