High-repetition-rate ultrafast fiber lasers

Abstract

Multi-gigahertz fundamental repetition rate, tunable repetition rate and wavelength, ultrafast fiber lasers at wavelengths of 1.0, 1.5, and 2.0 µm are experimentally demonstrated and summarized. At the wavelength of 1.0 µm, the laser wavelength is tuned in the range of 1040.1-1042.9 nm and the repetition rate is shifted by 226 kHz in a 3-cm-long all-fiber laser by controlling the temperature of the resonator. Compared with a previous work where the maximum average power was 0.8 mW, the power in this study is significantly improved to 57 mW under a launched pump power of 213 mW, thus achieving an optical-to-optical efficiency of 27%. For comparison, a similar temperature-tuning technique is implemented in a Tm-doped ultrafast oscillator but, as expected, it results in a broader tunable range of 14.1 nm (1974.1-1988.2 nm) in wavelength as compared with the value of 1.8 nm for the wavelength of 1.0 µm. The repetition rate in the process is shifted by 294 kHz. For the high-frequency range from 100 kHz to 10 MHz, the value of integrated timing jitter gradually increases with an increase in temperature. Finally, to the best of our knowledge, for the first time, a new method for tuning wavelength and repetition rate is proposed and demonstrated for a femtosecond fiber laser at the wavelength of 1.5 µm. Through fine rotation of the alignment angle between the Er/Yb:glass fiber and a semiconductor saturable absorption mirror, the peak wavelength can be tuned in the range of 1591.4-1586.1 nm and the repetition rate is shifted by 60 kHz.

Robust 700 MHz mode-locked Yb:fiber laser with a biased nonlinear amplifying loop mirror

“…In addition, in the frequency range from 100 kHz to 10 MHz, the phase noise from both ports is −150 dBc/Hz, which is lower than the fiber laser reported in [10].The integrated timing jitter is 21 fs for both outputs, which is also lower than 90 fs of the 750 MHz NPE fiber laser .…”

“…4. The relative intensity fluctuation, indicated by the square root of the integral of the power spectral density (PSD) from 10 MHz to 10 Hz, is approximately 0.015% at PBS1 and 0.016% at PBS2, which is lower than the one of the laser in linear cavity based on SESAM mode locking [10]. We measured relative intensity noise of the 750 MHz fiber laser [20] based on NPE mode locking with the same detector.…”

“…Once the mode locking stops, the realignment and restarting may not recover the previous pulse status, which limits their suitability for industrial applications. On the other hand, linear cavity fiber laser by all polarization maintaining (PM) can achieve the gigahertz level fundamental repetition rate, because of the external fiber-tailed wavelength division multiplexer (WDM) [9,10]. However they must use saturable absorber to start mode locking which limits the pulse width and the output power.…”

Ultrafast Fiber Lasers: An Expanding Versatile Toolbox

“…Especially as the repetition rate exceeds 1 GHz, the cavity fiber is less than 10 cm in length and therefore the active fiber must be highly doped to provide enough gain. Table 1 lists representative ultrafast Yb-doped and Erdoped fiber oscillators fundamentally mode-locked with the repetition rate beyond 150 MHz (Byun et al, 2010;Chen et al, 2007Chen et al, , 2012bCheng et al, 2017Cheng et al, , 2018Du et al, 2017;Huang et al, 2017;Ilday et al, 2005;Li et al, 2013Li et al, , 2014aLi et al, , 2014bLi et al, , 2015Liu et al, 2018;Ma et al, 2010;Martinez andYamashita, 2011, 2012;Song et al, 2019aSong et al, , 2019bWang et al, 2011Wang et al, , 2019Wu et al, 2015a;Xing et al, 2015;Yang et al, 2012;Zhang et al, 2016).…”

“…Such a compact Yb-fiber oscillator produces 3-GHz pulses with the pulse duration as short as 206 fs (Chen et al, 2012b). Recently, Yb-fiber oscillators with >5-GHz repetition rate are demonstrated (Cheng et al, 2017(Cheng et al, , 2018Liu et al, 2018;Wang et al, 2019); without dispersion compensation, these oscillators emit picosecond pulses. In contrast, highly doped Er-fibers have negative GVD and the resulting oscillators can operate at soliton mode-locking regime without requirement of dispersion compensation.…”