An 80 W 350-2400 nm monolithic supercontinuum (SC) source is reported. The high-power SC is generated in a uniform multi-core photonic crystal fiber (PCF) pumped by a 1016 nm pulsed fiber laser. The specially designed PCF has seven 4.5 μm diameter cores, a 0.85 air-filling fraction, and a zero dispersion wavelength (ZDW) of 991 nm. The 1016 nm pulsed laser delivers up to 114 W average power, which is believed to be the highest currently reported for picosecond fiber lasers working below 1020 nm. In order to ensure a robust and compact all-fiber structure, the pump laser is fusion spliced to the PCF using a selective air-hole collapse technique, achieving an ultra-low splicing loss of 0.2 dB despite the severe mode field mismatch. The proximity of the pump wavelength to the ZDW of PCF leads to enhanced visible generation. The output SC has a high spectral density of up to 108 mW/nm (at 580 nm) and over 50 mW/nm across the entire visible waveband. The achieved short-wavelength edge and high-spectral-power density in the visible region, to the best of our knowledge, are the best results reported for high-power visible SC sources.

We experimentally demonstrate an all-fiber, ultraviolet-enhanced, supercontinuum generation in a specifically designed seven-core photonic crystal fiber pumped by a picosecond Yb-doped master oscillator power amplifier (MOPA). The MOPA source is seeded by a giant-chirped Yb-doped mode-locked fiber laser operating in the dissipative-soliton-resonance (DSR) region. The DSR is achieved by using a nonlinear optical loop mirror (NOLM) with a fundamental repetition rate of 4.5 MHz and a central wavelength of 1035 nm. An extremely wide optical spectrum spanning from 350 nm to 2400 nm is obtained with a total output power of 6.86 W.

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LIST OF TABLES A Comparison of the F irs t Ten Exact Poles and Estimated Zeros in the s-doma1n (Upper Left Half Plane) fo r the Simulated Model 1n Equation (3 .2) A Comparison of the F irs t Six Exact Poles and Estimated Zeros in the s-domain (Upper Left Half Plane) for the Conducting Thin Straight Wire A Comparison of the F irs t Ten Exact Poles and Estimated Zeros 1n the s-domain (Upper Left Half Plane) for the Conducting Thin C ircular Loop A Comparison of the F irs t Ten Exact Poles and Estimated Zeros in the s-doma1n (Upper Left Half Plane) for the Conducting Sphere A Comparison of the Estimated F irs t Ten Poles in the s-domain (Upper Left Half Plane) for the Conducting C ircular Disk Radian Frequency Difference Between Consecutive Poles Summary of Radian Frequency Differences and Its Corresponding Time A Comparison of the Zeros Obtained Using Two K-pulses with D ifferen t Durations (The Target 1s a Straight Wire) A Comparison of the Zeros Obtained Using Two K-pulses with D ifferen t Durations (The Target is a C ircular Loop) A Comparison of the Zeros Obtained Using Two K-pulses with D ifferen t Durations (The Simulated Model 1s in Equation (3 .2)) A Comparison of the Zeros Obtained Using Two K-pulses with D ifferen t Durations (The Target 1s a Conducting Sphere) A Comparison of the Zeros Obtained Using Two K-pulses with D ifferen t Durations (The Target 1s a C ircular Disk) vi

Purpose The purpose of this paper is to identify the energy losses factors during the hydro-mechanical conversion process at high pressure via a novel reduced order dynamic model. Design/methodology/approach A novel reduced order dynamic model of the axial piston motor was proposed, which provides an explicit insight to the compression flow losses and the Coulomb friction losses. A fully coupled dynamic model of the piston motor was obtained based on the array bond graph method. And then, a reduced order model was obtained by the composition analysis of flow and torque of the axial piston motor. After that, the energy losses estimation model was presented to predict the energy loss of the piston motor under a wide range of working conditions. The model was verified by comparing the experimental and simulation results. Findings The simulation result indicates that the flow loss caused by oil compression accounts for 59 per cent of the total flow loss, and the Coulomb friction torque accounts for 40 per cent of the total torque loss under a specific working condition. The compression flow loss and Coulomb friction torque are the major factors that lead to the aggravation of energy loss under extreme working conditions of the piston motor. Originality/value At high-pressure condition, the compression flow losses due to fluid compressibility cannot be neglected, and the hydro-mechanical losses in varies friction pairs should involve Coulomb friction losses. Flow and torque loss analytical expression in the model involve the design and control parameters of the piston equipment, which can realize the parameter optimization of the piston equipment for the purpose of energy-saving.