- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Burst-mode 500 ps fiber laser ablation in 304 stainless steel
摘要： A study on burst-mode 500 ps fiber laser ablation in 304 stainless steel is presented. A 500 ps pulsed fiber laser with burst-mode operation was employed as the light source in our laser processing system. Under different laser parameters, the ablation results were observed and compared with scanning electron microscope photos. As the burst energy was 8 mJ and the pulse repetition rate was 2 MHz, a relatively good hole quality was obtained. The superiority of burst-mode operation is also discussed at the end of this article.
关键词： laser micro-processing,sub-picosecond pulse,fiber laser,burst-mode
更新于2025-09-23 15:21:01
-
Analysis and Design of a CMOS Ultra-High-Speed Burst Mode Imager with In-Situ Storage Topology Featuring In-Pixel CDS Amplification
摘要： This paper presents an in-situ storage topology for ultra-high-speed burst mode imagers, enabling low noise operation while keeping a high frame depth. The proposed pixel architecture contains a 4T pinned photodiode, a correlated double sampling (CDS) amplification stage, and an in-situ memory bank. Focusing on the sampling noise, the system level trade-off of the proposed pixel architecture is discussed, showing its advantages on the noise, power, and scaling capability. Integrated with an AC coupling CDS stage, the amplification is obtained by exploiting the strong capacitance to the voltage relation of a single NMOS transistor. A comprehensive noise model is developed for optimizing the trade-off between the area and noise. As a proof-of-concept, a prototype imager with a 30 μm pixel pitch was fabricated in a CMOS 130 nm technology. A 108-cell memory bank is implemented allowing dense layout and parallel readout. Two types of CDS amplification stages were investigated. Despite the limited memory capacitance of 10 fF/cell, the photon transfer curves of both pixel types were measured over different operation speeds up to 20 Mfps showing a noise performance of 8.4 e?.
关键词： burst mode,million frames per second,ultra-high-speed imaging,in-pixel amplification,in-situ storage,image sensors
更新于2025-09-23 15:21:01
-
Burst-Mode Synchronization for SOQPSK
摘要： We consider a comprehensive synchronization strategy for burst-mode transmission of shaped-offset quadrature phase-shift keying (SOQPSK) signals over the additive white Gaussian noise (AWGN) channel. Due to the similarities between SOQPSK and continuous phase modulation (CPM), we make use of recent results for synchronization of burst-mode CPMs. We first derive a training sequence that is optimal in the sense that it jointly minimizes the Cramér–Rao bounds (CRBs) for frequency offset, phase offset, and timing offset estimation. Additionally, we develop a maximum likelihood (ML) data-aided (DA) algorithm for joint estimation of the synchronization parameters for SOQPSK signals. We show that the proposed algorithm for the optimal training sequence can be adapted to work with the suboptimal training sequence that is being considered for use in burst-mode network enhanced telemetry (iNET). This demonstrates an immediate practical application for our approach. We present numerical results on the mean-squared error (MSE) performance of the proposed algorithm for both training sequences and for different versions of SOQPSK. The numerical results show that our joint estimation algorithm yields performance that is very close to the CRBs for all three synchronization variables. Finally, we compare the overall performance of our proposed training sequence and synchronization algorithm for different sequence lengths by simulating a burst-mode SOQPSK receiver. This allows us to employ the right training sequence length based on the desired complexity and bit error rate (BER) performance.
关键词： Shaped-offset quadrature phase-shift keying (SOQPSK),synchronization,phase offset,timing offset,frequency offset,burst-mode transmission
更新于2025-09-19 17:15:36
-
High Conversion Efficiency, Mid-Infrared Pulses Generated via Burst-Mode Fiber Laser Pumped Optical Parametric Oscillator
摘要： We present a mid-infrared optical parametric oscillator (OPO) with a high pump-to-idler conversion efficiency from 1.06 μm to 3.8 μm, which was quasi-synchronously pumped by a burst-mode fiber laser. The pump pulse was specially designed with a rectangular profile in temporal, which was composed of hundreds of ultrashort sub-pulses. By applying the quasi-synchronous pumping scheme, the buildup time of the parametric signal pulse could be minimized. No back-conversion effect was observed when the pump peak power was increased. A maximum pump-to-idler conversion efficiency of 19.6% was achieved when the number of intra-burst sub-pulses was set to be 240. By increasing the number of intra-burst sub-pulses to be about 480, the maximum average output power of 7.9 W at 3.8 μm was realized under pump power of 45.3 W. The corresponding pump-to-idler conversion efficiency was computed to be about 17.5%. The experimental results show an improvement of 40% in pump-to-idler conversion efficiency for this quasi-synchronously pumped OPO when compared with the conventional long laser pulse pumped OPO.
关键词： burst-mode fiber laser,quasi-synchronously pumped,mid-infrared,optical parametric oscillator
更新于2025-09-19 17:13:59
-
[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - A Burst-mode Optical Amplifier for TWDM-PON
摘要： One of the critical challenges for TWDM-PON is that the optical amplifiers need to run in the burst-mode, with an up to 40 dB dynamic range. This presentation discusses the corresponding requirements and solutions.
关键词： TWDM-PON,Amplifier,Burst mode
更新于2025-09-16 10:30:52
-
[IEEE 2019 Eleventh International Conference on Ubiquitous and Future Networks (ICUFN) - Zagreb, Croatia (2019.7.2-2019.7.5)] 2019 Eleventh International Conference on Ubiquitous and Future Networks (ICUFN) - Fault Monitoring in Passive Optical Networks Using Burst-Mode FBG Optical Sensor
摘要： This paper presents a fault monitoring method in passive optical networks (PON) using Burst-mode uniform FBG optical sensors. The proposed monitoring method detects physical layer faults between optical line terminal (OLT) and optical network units (ONUs). The FBG interrogation subsystem located in central office (CO) near OLT transmits FBG monitoring signal to every ONU. Each ONU branch contains an FBG sensor subsystem. The proposed system provides Burst mode upstream data transmission using time division multiple access (TDMA). We show that the proposed system is a cost- effective solution that has ability to monitor faults of any ONU branches in PON.
关键词： Fiber Bragg Grating,Fault Monitoring in PON,Burst-Mode uniform FBGs
更新于2025-09-16 10:30:52
-
Surface ablation efficiency and quality of fs lasers in single-pulse mode, fs lasers in burst mode, and ns lasers
摘要： In recent years, the burst-mode caught a lot of attention in the field of ultrashort-pulse laser micro machining. One of the major issues is the influence of the burst pulse number and frequency on ablation efficiency and quality. A recent publication reported of a significant increase in ablation efficiency when processing with ≥ 25 burst pulses at ≥ 100 MHz burst frequencies. This raises the question of whether processing with such high pulse densities can be attributed to non-thermal ablation, or whether a quasi-nanosecond laser ablation behavior is achieved. To answer this question, we determined ablation efficiencies as function of fluence for silicon, stainless steel, and copper and compared the ablation quality at the optimal fluence using the following laser systems: femtosecond laser operated in single-pulse mode, fs laser operated in 28-pulse-burst mode with a burst pulse frequency of 148 MHz, and a nanosecond laser with a pulse duration of 175 ns, which is identical with the temporal length of the burst pulse train. The comparison showed that the burst mode used produces similar surface morphologies and melt burrs as the nanosecond laser, but at about 2/3 of its efficiency.
关键词： burst mode,ablation efficiency,silicon,laser ablation,copper,steel
更新于2025-09-12 10:27:22
-
Heat accumulation effects in laser processing of diamond-like nanocomposite films with bursts of femtosecond pulses
摘要： In this paper, we have investigated the burst mode (BM) ablation and surface structuring of diamondlike nanocomposite (DLN) a-C:H:Si:O films with femtosecond laser pulses (wavelength λ = 515 nm, pulse duration τ = 320 fs, and pulse repetition rate f = 100 kHz) under different scanning conditions (single spots and linear structures). The pulse separation in the bursts is 25 ns (intraburst frequency f = 40 MHz), and the pulse number is varied from 1 to 8. The ablation depth and specific ablation rates (μm3/μJ) are found to be higher for the burst mode compared to single-pulse irradiation, increasing with the pulse number in the burst. The obtained experimental data of the higher ablation efficiency are shown to correlate with computer simulations of the BM ablation. In correlation with the ablation findings, Raman spectra of single spots and microgrooves have evidenced a growing graphitization of the amorphous film structure with the pulse number in the bursts (at an equal energy deposited into the films). Contact-mode atomic force microscopy (AFM) is applied to reveal an influence of the BM processing on the surface properties (nanoscale relief, friction) of laser-structured films. Based on the ablation and Raman data analysis, AFM examination of ablated/redeposited layers, and computer simulations of the burst mode ablation, the heat accumulation is identified as the main factor responsible for the enhanced ablation efficiency during the BM processing of DLN films. In addition, results of the high precision surface microstructuring of DLN films in the burst mode are presented.
关键词： heat accumulation,diamondlike nanocomposite films,surface structuring,femtosecond laser pulses,burst mode ablation
更新于2025-09-12 10:27:22
-
[Laser Institute of America ICALEO? 2016: 35th International Congress on Applications of Lasers & Electro-Optics - San Diego, California, USA (October 16–20, 2016)] International Congress on Applications of Lasers & Electro-Optics - High power UV laser processing of CFRP with various ns pulses
摘要： While achieving high cutting speed, minimizing thermal damage is one of the important issues in the laser processing of Carbon Fiber-Reinforced Plastic (CFRP). Among the various parameters in the laser processing, we focused on pulse waveforms to investigate Heat Affected Zone (HAZ) occurrence and cutting speed using a high power (up to 60 W) 355-nm UV Quasar? laser from Spectra-Physics. Pulse width was varied from 2 ns to 10 ns and pulse splitting and burst mode technology using TimeShift? capability of laser was tested to cut 250 μm thick CFRP sheets. It was found that shorter pulse widths and pulse splitting were both effective at reducing HAZ and increasing cutting speed for PAN-based CFRP.
关键词： burst mode,pulse width,UV laser,CFRP,HAZ,cutting speed,pulse splitting
更新于2025-09-11 14:15:04
-
Highly-efficient laser ablation of copper by bursts of ultrashort tuneable (fs-ps) pulses
摘要： Ultrashort pulse laser, capable of varying pulse duration between 210 fs and 10 ps and producing a burst of pulses with an intra-burst pulse repetition rate of 64.5 MHz (time distance between pulses 15.5 ns), was used to investigate the ablation efficiency of the copper. The study on ablation efficiency was done for various numbers of pulses per burst between 1 and 40. The increase in the ablation efficiency by 20% for 3 pulses per burst compared to a non-burst regime was observed. The comparison was made between the beam-size optimised regimes. Therefore, the real advantage of the burst regime was demonstrated. To the best of our knowledge, we report the highest laser milling ablation efficiency of copper of 4.84 μm3/μJ by ultrashort pulses at ~1 μm optical wavelength.
关键词： ultrashort pulse laser,laser milling,ablation efficiency,copper ablation,burst mode
更新于2025-09-11 14:15:04