All-fiber Chirped Pulse Amplification Research Articles

High-Power GHz Burst-Mode All-Fiber Laser System with Sub 300 fs Pulse Duration

An all-fiber low-repetition-rate SESAM mode-locked fiber oscillator combined with a dispersion-managed active fiber loop produces a flexible GHz burst-mode laser source. The high-power output is then produced by amplifying the GHz burst-mode laser source using an all-fiber chirped-pulse amplification system. Then, the laser is compressed using a grating pair compressor; a maximum amplified power of 97 W is obtained. This results in a compressed high power of 82.07 W with a power stability RMS of 0.09% and beam quality better than 1.2. Accurate dispersion control allows for the production of a high-quality pulse duration of 265 fs.

A Wide Spectrum Yb-Doped All-Fiber-Integrated Chirped Pulse Amplification System Based on Parabolic Shaping

Nonlinear effect in an ultrafast fiber laser has always been a major obstacle in realization of laser with narrow pulse width and high energy. To achieve higher peak power, we herein introduce pre-chirping management and pre-amplification before the chirped pulse amplification (CPA) system. The self-phase modulation effect is used to effectively stretch the spectrum when the pulse reaches a high peak power, and then the parabolic pulse and spectrum are obtained in a fiber amplifier. This parabolic pulse effectively reduces the impact of nonlinear effect in subsequent fiber amplifier and realizes the amplification of chirped pulse with a higher peak power compared with conventional CPA system. We finally achieved a mode-locked pulse with 143 fs pulse duration, 8.57 W average power, 85.7 μJ single pulse energy, M2 < 1.10 beam quality, and without obvious pulse degeneration. The reported pulse energy is the highest among all-fiber CPA systems based on nonlinear amplification technology.

All-polarization-maintaining mode-locked thulium-doped femtosecond laser at 1.7 µm

We demonstrate a 1.7 µm femtosecond Tm-doped fiber laser system featuring an all-polarization-maintaining architecture. The seed oscillator is mode-locked by carbon nanotubes and delivers stable pulse centered at 1787.6 nm. With two backward pumped amplifiers, the average power of the laser is amplified to ∼458 mW. Employing proper dispersion management in an all-fiber chirped pulse amplification scheme and the soliton compression effect, we obtained a femtosecond pulse of 206 fs with a pulse energy of 8.8 nJ at a repetition rate of ∼52 MHz. To the best of our knowledge, this is the first demonstration of 1.7 µm femtosecond laser based on a thulium-doped oscillator with all-polarization-maintaining architecture.

A large dispersion-managed monolithic all-fiber chirped pulse amplification system for high-energy femtosecond laser generation

A high energy monolithic all fiber chirped pulse amplification (CPA) system composed of fiber-silicate glass fiber is demonstrated in this work. In this compact system, the optical stretcher consists of two large dispersion chirped fiber Bragg gratings that offer a high stretch ratio to lower the nonlinearity that accumulates in the fiber amplifier. By employing high gain silicate glass fiber with a length of 20 cm as the main amplifier, an optimal balance of pulse energy and the B-integral is achieved. An amplified power of 42.6 W, corresponding to a pulse energy of 213 µJ, is obtained with an injection power of 100 mW. After compression, the laser pulses are compressed by a novel polarization-controlled double-pass configuration of a chirped volume Bragg grating (CVBG) to match the dispersion of the fiber stretcher. A total compression efficiency of 79.8% is obtained. The dispersion between the stretcher and the compressor is matched with the self-made temperature tuning device of the fiber grating. An optimized pulse width of 781 fs and a pulse energy of 170 µJ are obtained with the single-mode beam profile. To the best of our knowledge, this is the highest energy ever obtained with a single-mode beam profile for a spliced monolithic all-fiber CPA system. This compact high-energy fiber system will be useful in scientific research and industrial applications.

W-type normal dispersion thulium-doped fiber-based high-energy all-fiber femtosecond laser at 1.7 µm.

We propose a parabolic W-type thulium-doped fiber for the 1.7 µm high-energy femtosecond pulsed laser. Despite its attractive normal dispersion, the fiber offers high gain in 1.7 µm region thanks to its distributed short-pass filtering effect. With a proper dispersion management in an all-fiber chirped pulse amplification (CPA) scheme, we demonstrate so far the highest pulse energy of 128.0 nJ in a stable pulse of 174 fs in the 1.7-1.8 µm region, which marks above an order of magnitude improvement in pulse energy while exhibiting the shortest pulse duration among fiber-based CPA works at 1.7 µm. Hence, we provide a pathway to an energy scalable and efficient femtosecond laser at 1.7 µm via a compact and elegant all-fiber solution.

Polarization-dependent dissipative soliton intensity modulation enabled repetition-rate-switchable CPA system

We report a watt-level, repetition-rate-switchable all-fiber chirped pulse amplification (CPA) system by using polarization-dependent dissipative soliton intensity modulation effect. The intensity modulation for pulse repetition rate tuning is realized by combination of the polarization discrimination device (i.e., polarizer) and the polarization-rotating vector soliton (PRVS). Up to ~100% intensity modulation depth with a period of two cavity roundtrips for the PRVS seed was obtained by adjusting the dissipative soliton polarization state that was injected into the polarizer. Relying on this mechanism, the repetition rate of the output pulse from the CPA system can be dynamically switched between 1.37 MHz and 2.74 MHz. The pulse energy of ~2.0 μJ and ~2.2 μJ were achieved for the repetition rates of 1.37 MHz and 2.74 MHz, corresponding to 1.12 ps and 970 fs pulse duration, respectively. These findings would provide an alternative method for dynamic tuning of pulse repetition rate in high power laser systems, which also underpins the significance of fundamental research of vector dissipative solitons in practical applications such as flexible high-energy pulse laser systems.

Sub-picosecond all-fiber chirped-pulse amplification system based on photonic crystal fibers’ spectral broadening and chirped-volume Bragg grating compression

In this paper, a 38.7 W amplified (24.8 W compressed) picosecond ytteribium-fiber chirped-pulse amplification system at 1030.3 nm is demonstrated using chirped-volume Bragg grating for the compressor and photonic crystal fiber for the spectral stretcher. For optimizing compressed pulse duration, the spectral width is fine-tuned by controlling the length, dispersion and the parameters of the nonlinear of the photonic crystal fiber, which is an additional dispersion compensation method to eliminate the residual dispersion in the chirped-pulse amplification system. As a result, the chirped pulse width of 330 ps is amplified in ytteribium-doped fiber amplifier and subsequently, re-compressed to 1.1 ps duration corresponding to the peak power of 1.1 MW.

50 μJ Femtosecond Laser System Based on Strictly All-Fiber CPA Structure

We demonstrate a strictly all-polarization maintaining, all-fiber chirped pulse amplification of ultrashort pulses. Pulses with the duration of 933 fs and energy as high as 50 μJ are achieved at 200 kHz repetition rate in a compact size. The variations of the spectra and pulse widths as functions of the amplified output power have also been presented. To our best knowledge, this is the highest energy extracted from the strictly all-fiber chirped pulse amplification system. The environmentally stable femtosecond laser source will find various applications in practice.

高功率全光纤啁啾脉冲放大激光系统

高功率全光纤啁啾脉冲放大激光系统

Dispersion compensation technologies for femtosecond fiber system

Developed highly chirped broadband fiber Bragg gratings and suspended-core fibers are shown to offer flexible dispersion management and allow for femtosecond oscillators with transform-limited pulse quality. Such dispersion compensators could have potential, particularly for all-fiber chirped-pulse amplification systems.

Polarization-maintaining fiber pulse compressor by birefringent hollow-core photonic bandgap fiber

Structural birefringent properties of a hollow-core photonic-bandgap fiber were carefully investigated and applied to all-fiber chirped-pulse amplification as a compressor. The group birefringence of as high as 6.9x10(-4) and the dispersion splitting by as large as 149 ps/nm/km between the two principal polarization modes were observed at 1557 nm. By launching the amplifier output to one of the polarization modes a 17-dB polarization extinction ratio was obtained without any pulse degradation originating from polarization-mode dispersion. A hybrid fiber stretcher effectively compensates the peculiar dispersion of the photonic-bandgap fiber and pedestal-free 440-fs pulses with a 1-W average power and 21-nJ pulse energy were obtained. Polarization-maintaining fiber-pigtail output of high-power femtosecond pulses is useful for various applications.

High-Peak-Power Ultrashort Pulse Generation Using All-Fiber Chirped Pulse Amplification System with Small Core Multimode Fiber

We present an all-fiber chirped pulse amplification system based on a normally dispersive single mode Er-doped fiber and a multimode fiber of 25 µm core diameter. The 260 fs sech2 transform-limited pulses generated in a passively mode-locked Er-doped fiber laser are stretched to 1 ps and amplified in an Er-doped fiber amplifier. Then the subsequent multimode fiber in which the pulses propagate only in the fundamental mode compresses the pulses to 80 fs. The pulse compression using the conventional multimode fiber as a large-core single-mode fiber is demonstrated for the first time. The peak power of the output pulses is increased to 44 kW.

Chirped pulse Raman amplification with compression in air-core photonic bandgap fiber

An all-fiber chirped pulse amplification scheme based on Raman amplifiers and compression in air-core photonic bandgap fiber is demonstrated for the first time. Pulse chirping was achieved through nonlinear propagation in the amplifiers and a net compression factor of 53 was achieved. Output pulses presented sub-picosecond durations. Output peak powers approached 1 kW, being 3 orders of magnitude higher than those obtainable with Raman amplifiers without the chirped pulse amplification setup. The demonstrated scheme may instigate the use of fiber Raman amplifiers outside optical communications, as it is simple, robust, and may be built to operate at virtually any optical wavelength.

Slicing the supercontinuum radiation generated in photonic crystal fiber using an all-fiber chirped-pulse amplification system

We report on an experimental study of supercontinuum broadening in photonic crystal fiber performed by measuring the temporal behavior of spectrally-sliced radiation in different propagation regimes. The study confirms the soliton fission theory by observing the red-shifted fundamental solitons and blue-shifted nonsolitonic radiation.

An optimized Er gain band all-fiber chirped pulse amplification system

We demonstrate an all-fiber Er chirped pulse amplification (CPA) system based on compression in photonic band gap fiber (PBGF) that produces 570 fs pulses with 312 nJ pulse energy. The dispersion of the PBGF is measured precisely and used to design a dispersion-matched nonlinearly-chirped fiber Bragg grating stretcher. We analyze the trade-offs of such all-fiber CPA system design and compare different PBGFs in terms of the derived figure of merit. Such system architecture should be scalable to few micro-Joule level pulse energies close to the compressor nonlinearity limit when PBGFs with improved figure of merit become available.

All-fiber chirped pulse amplification using highly-dispersive air-core photonic bandgap fiber

We show, for the first time to our knowledge, all-fiber chirped pulse amplification using an air-core photonic bandgap fiber. Pulses from a wavelength- and duration-tunable femtosecond/picosecond source at 10 GHz were dispersed in 100 m of dispersion compensating fiber before being amplified in an erbium-doped fiber amplifier and subsequently recompressed in 10 m of the anomalously dispersive photonic bandgap fiber. Pulses as short as 1.1 ps were obtained. As air-core fibers present negligible nonlinearity, the presented configuration can potentially be used to obtain ultra-high pulse peak powers. A study of the air-core fiber dispersion and dispersion slope is also presented.

Femtosecond pulse amplification in cladding-pumped fibers

Femtosecond pulse amplification in a cladding-pumped fiber amplifier is demonstrated for the first time to our knowledge. Using a cladding-pumped erbium-doped fiber power amplifier and a passively mode-locked fiber seed oscillator in conjunction with an all-fiber chirped-pulse amplification system, we obtain 380-fs near-bandwidth-limited pulses with an average power of 260 mW. The pulse repetition rate is varied between 5 and 50 MHz, and pulse energies as high as 20 nJ are generated.