- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Performance characterization of continuous-wave laser-induced forward transfer of liquid bioink
摘要： Herein, we propose a continuous-wave laser-induced forward transfer (CW-LIFT) system that possesses high printing quality with a high printing success rate. CW-LIFT can automatically deposit droplets equally and uniformly as a customized pattern. In this study, we selected an 830 nm near-infrared CW laser and applied a 20× microscope objective lens to highly focus the laser beam. In addition, a 16 nm gold thin film was used as the energy-absorbing layer for CW-LIFT. We demonstrated that the CW-LIFT can print liquid bioink and deposit cells in a controlled and precise way.
关键词： bioink,continuous-wave laser-induced forward transfer,laser printing,CW-LIFT,cell deposition
更新于2025-09-11 14:15:04
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Continuous-wave laser diodes based on epitaxially integrated InGaAs/AlGaAs/GaAs heterostructures
摘要： We report the results of the development and investigation of the main characteristics of integrated laser emitters for the spectral range from 1040 to 1080 nm. These devices are fabricated using epitaxially integrated InGaAs/AlGaAs/GaAs heterostructures with one or two emitting regions, and measurements are performed in pulsed, quasi-continuous, and continuous-wave pump regimes. It is found that along with the obvious advantage of integrated emitters – an increase in the output optical power, they also have a significant limitation, which consists in increasing the amount of released heat. Despite this, it is shown that such integrated double laser diodes operate efficiently in the continuous-wave generation regime (Pmax ~ 6 W), demonstrating a 1.7-fold increase in the differential quantum efficiency as compared to single laser diodes.
关键词： continuous-wave regime,laser diode,epitaxially integrated heterostructure,heat release
更新于2025-09-11 14:15:04
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Precision locking CW laser to ultrastable optical frequency comb by feed-forward method
摘要： We locked a 1064 nm continuous wave (CW) laser to a Yb:fiber optical frequency comb stabilized to an ultrastable 972 nm CW laser with the feed-forward method. Consequently, the stability and coherent properties of the ultrastable laser are precisely transferred to the 1064 nm CW laser through the frequency comb’s connection. The relative linewidth of the frequency-stabilized 1064 nm CW laser is narrowed to 1.14 mHz, and the stability reaches 1.5 × 10?17/s at the optical wavelength of 1064 nm. The phase noise characterization in the 1 mHz–10 MHz range is presented to indicate that feed-forward locking a CW laser to an ultrastable comb will offer a potential technique for many important applications, such as optical frequency synthesis and gravitational wave detection.
关键词： feed-forward method,continuous wave laser,phase noise,frequency stability,optical frequency comb
更新于2025-09-11 14:15:04
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Multi-Target Detection Method Based on Variable Carrier Frequency Chirp Sequence
摘要： Continuous waveform (CW) radar is widely used in intelligent transportation systems, vehicle assisted driving, and other fields because of its simple structure, low cost and high integration. There are several waveforms which have been developed in the last years. The chirp sequence waveform has the ability to extract the range and velocity parameters of multiple targets. However, conventional chirp sequence waveforms suffer from the Doppler ambiguity problem. This paper proposes a new waveform that follows the practical application requirements, high precision requirements, and low system complexity requirements. The new waveform consists of two chirp sequences, which are intertwined to each other. Each chirp signal has the same frequency modulation, the same bandwidth and the same chirp duration. The carrier frequencies are different and there is a frequency shift which is large enough to ensure that the Doppler frequencies for the same moving target are different. According to the sign and numerical relationship of the Doppler frequencies (possibly frequency aliasing), the Doppler frequency ambiguity problem is solved in eight cases. Theoretical analysis and simulation results verify that the new radar waveform is capable of measuring range and radial velocity simultaneously and unambiguously, with high accuracy and resolution even in multi-target situations.
关键词： continuous wave radar systems,Doppler ambiguity,variable carrier frequency chirp sequence,multi-target detection
更新于2025-09-10 09:29:36
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[IEEE 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Honolulu, HI, USA (2018.7.18-2018.7.21)] 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Hybrid multi-wavelength photoacoustic imaging
摘要： Multi-wavelength photoacoustic (PA) imaging has been studied extensively to explore the spectroscopic absorption contrast of biological tissues. To generate strong PA signals, a high-power wavelength-tunable pulsed laser source has to be employed, which is bulky and quite expensive. In this paper, we propose a hybrid multi-wavelength PA imaging (hPAI) method based on combination of single-wavelength pulsed and multi-wavelength continuous-wave (CW) laser sources. By carefully controlling laser illumination sequence (pulse-CW-pulse), and extracting the PA signals’ difference before and after heating of CW lasers, the optical absorption property of multi-wavelength CW lasers could be obtained. Compared with conventional PA imaging, the proposed hPAI shows much lower system cost due to the usage of single-wavelength pulsed laser and cheap CW lasers. Theoretical analysis and analytical model are presented in this paper, followed by proof-of-concept experimental results.
关键词： photoacoustic imaging,continuous-wave laser,multi-wavelength,pulsed laser,hybrid imaging
更新于2025-09-10 09:29:36
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[IEEE 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz2018) - Nagoya, Japan (2018.9.9-2018.9.14)] 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - All-Electronic High-Resolution Terahertz Thickness Measurements
摘要： Broadband laser based terahertz systems become currently established for inline multilayer paint inspection in the automotive industry. This technology has also proven to be suitable for inspections of certain multilayer plastic structures with up to a few millimeters of thickness. We present a complementary technique for the measurement of dielectric multilayer structures with thicknesses of submillimeter to several centimeters, using frequency-modulated continuous-wave electronic transceivers. In order to resolve layers below the inherent resolution limit by the modulation bandwidth, we take advantage of model-based signal processing techniques.
关键词： signal processing,thickness measurements,frequency-modulated continuous-wave,terahertz,multilayer structures
更新于2025-09-10 09:29:36
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All-Directions Through-the-Wall Imaging Using a Small Number of Moving Omnidirectional Bi-Static FMCW Transceivers
摘要： Through-the-wall radar imaging is a powerful tool for mapping buildings’ interiors and hidden objects behind the walls. Through-the-wall imaging systems require large linear arrays of directive antennas to form a large aperture for obtaining images with a high cross-range resolution. However, the low mobility and limited field of view of the conventional systems limit their imaging capability. The concept of all-directions through-the-wall imaging has recently been proposed to enhance the mobility, cross-range resolution, and field of view of the through-the-wall imaging systems. In this technique, the large linear array of directive antennas is replaced by a dense 2-D synthetic array formed by small moving transceivers utilizing omnidirectional antennas. The 2-D synthetic array provides 360° high cross-range resolution images. This paper focuses on the implementation of a system realizing all-directions through-the-wall imaging and measurement results. A bi-static frequency-modulated continuous wave (FMCW) radar system utilizing a simple wireless synchronization scheme and wideband omnidirectional antennas is fabricated and an image formation technique compatible with bi-static FMCW imaging system is presented. Measurement results show that the imaging system can provide 360° high-resolution image of objects and walls in a short time.
关键词： through-the-wall imaging,Bi-static,frequency-modulated continuous wave (FMCW),circular polarization,synthetic aperture,imaging
更新于2025-09-10 09:29:36
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24-GHz Self-Injection-Locked Vital-Sign Radar Sensor With CMOS Injection-Locked Frequency Divider Based on Push-Push Oscillator Topology
摘要： In this letter, a 24-GHz CMOS injection-locked frequency divider (ILFD) based on the push–push oscillator topology is designed and fabricated. It is further treated as the kernel component of a self-injection-locked (SIL) radar sensor for noncontact vital-sign detection. The push–push topology is employed to double the oscillation frequency of the 12-GHz LC oscillator to provide the 24-GHz transmitting signal of the radar sensor, while the direct injection-locked configuration is used to divide the receiving 24-GHz injection signal by 2. Hence, the 12-GHz output of the ILFD can be connected with a differentiator-based envelope detector for vital-sign demodulation. By packaging the developed ILFD chip and connecting it with two antennas, a gain block, a differentiator-based envelope detector, and a 24-GHz SIL radar sensor can be built to detect the physiological chest movement of a human subject. The feasibility of developing a SIL radar sensor in the millimeter-wave range is also demonstrated.
关键词： self-injection-locked (SIL) radar,push–push oscillator,noncontact vital-sign sensor,Continuous-wave (CW) radar,injection-locked frequency divider (ILFD)
更新于2025-09-09 09:28:46
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[IEEE 2018 15th European Radar Conference (EuRAD) - Madrid, Spain (2018.9.26-2018.9.28)] 2018 15th European Radar Conference (EuRAD) - Orthogonal Waveform Designs for Pulse-Based and Continuous-Wave MIMO Radars
摘要： We investigate orthogonal waveform designs for pulse-based and continuous-wave multiple-input multiple-output (MIMO) radars. For the pulse-based MIMO option, we study different intra-pulse modulation schemes based on both linear and non-linear frequency modulation (LFM/ NLFM) and establish approximate orthogonality between the transmit antennas by means of frequency shifts and up-/down chirp combinations. For the continuous-wave MIMO option, we study a range-domain technique based on M-sequences and show that the range sidelobe behavior can be signi?cantly improved by employing suitable mismatched ?ltering (MMF) at the receiver.
关键词： MIMO radar,M-sequences,orthogonal waveforms,pulse-based radar,continuous-wave radar,LFM,NLFM,mismatched filtering
更新于2025-09-04 15:30:14
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Room-Temperature Continuous-Wave Frequency-Referenced Spectrometer up?to?7.5?THz
摘要： The lack of coherent room-temperature sources in the whole terahertz spectral window (0.3–10 THz) has significantly hampered the growth of scientific and technological applications in this range. Among them, high-precision frequency measurements of molecular transitions play a central role but remain an open challenge. Here, room-temperature generation and detection of continuous-wave, broadly tunable, narrow-linewidth THz radiation are presented, and their application to high-resolution spectroscopy in the broad 1–7.5 THz spectral range is demonstrated. This result has been achieved by implementing a Cherenkov phase-matching scheme into a channel waveguide in a nonlinear crystal. This simple approach, entirely based on robust telecom technology, unprecedently merges in a single source an ultra-broad continuous-wave spectral coverage and a state-of-the-art accuracy (approximately 10?9) in molecular-transition-center determination.
关键词： terahertz,continuous-wave,frequency-referenced,spectroscopy,Cherenkov phase-matching
更新于2025-09-04 15:30:14