We demonstrate a hundred micro-Joules level femtosecond laser system based on a compact and simple two-stage Yb:YAG single crystal fiber chirped pulse amplification system which delivers compressed power of 15.57 W, pulse width of 715 fs. The different amplification performance with different input seed power is experimentally studied. A maximum direct amplified power output of 44 W at 100 kHz is obtained for an input seed power of 12 W. To the best of our knowledge, this is the highest average power of femtosecond laser based on single crystal fiber at hundred micro-Joules energy level.

Based on the time-independent rate equations and nonlinear Schrödinger equation, we simulate a 200 MHz all-polarization-maintaining (PM) mode-locked Yb-doped fiber laser. The cavity round trip evolution toward stable mode locking is present. Additionally, the gain coefficients along the gain fiber as well as the pulses, chirp, and spectra at different locations in the cavity are examined. The effects of chirped fiber Bragg grating parameters on the pulse shape and spectrum profile are also investigated. According to the calculations, we experimentally realize a 200 MHz femtosecond fiber laser with 115 mW output power. The timing jitter and integrated relative intensity noise are measured as 158 fs (1 kHz to 10 MHz) and 0.0513% (1 Hz to 300 kHz), respectively. Eventually, an amplified average power of 610 mW and 79 fs compressed pulses with a peak power of approximately 28 kW are obtained. The exhibited all-PM femtosecond fiber laser system can be adopted as the foundation for an optical frequency comb.

We present a dual fiber laser system that comprises two compact all-polarization-maintaining fiber lasers. The main feature of this laser system is that, facilitated by self-made fiber actuators, the repetition rates of the sub lasers can be tuned across wide ranges and phase-locked with high stability and low phase noise. The fiber actuator consists of a PZT coupled with an annular displacement amplifier. Through an optimized design of the displacement amplifier’s structure, we achieve not only large tuning ranges of 42 kHz (laser 1) and 49 kHz (laser 2) at a repetition rate of around 100 MHz but also a response bandwidth exceeding 1 kHz when the repetition rates are phase locked. Moreover, the self-made actuator demonstrates a lower insertion loss (0.37 dB) compared to commonly used delay lines (1.5 dB). After locking, the relative instability of the repetition rates remains superior to 2.28 × 10⁻¹² (1s gate time) even under an external temperature variation of up to 20°C. In the presence of environmental disturbances, including temperature fluctuations, humidity, and vibrations, the repetition rate stability of both lasers is kept within 5.1 × 10⁻¹². Furthermore, due to an effective suppression of phase noise at offset frequencies below 1 kHz, the integrated timing jitters are both smaller than 217 fs [1 Hz-1 MHz]. As a performance proof, the ability to eliminate the dead zone based on our dual fiber laser system is verified through an absolute distance measurement experiment. Additionally, long optical fiber spools with nominal lengths of 8 m, 50 m, 100 m, and 235 m were precisely measured, achieving standard deviations of less than 166 μm, which improved to 15.1 μm after averaging every 200 data points. This result validates the system's capability for long-distance measurements.

The large volume and weak environmental adaptability of fiber optical frequency combs (OFCs) have become the main obstacles for their applications in various fields. To address these issues, in this study, we present a compact, low-cost f-to-2f interferometer and fiber actuator with a large tuning range and a high control bandwidth for a 200-MHz OFC that is based on a 1.5-m all-polarization-maintaining fiber mode-locked laser. By employing customized fiber-coupled gradient index lenses, our f-to-2f interferometer is encapsulated in a miniature tube with a diameter of only 4 mm and a length of 40 mm, which substantially reduces the optical section size of the frequency comb as compared to conventional devices. The carrier envelope offset beat with a signal-to-noise ratio of 40 dB is detected in a resolution bandwidth of 360 kHz. In addition, a laboratory-made piezoelectric transducer-driven mechanical actuator for repetition rate regulation exhibited a large tuning range of 106 kHz (corresponding to an effective temperature drift of 53) and a high control bandwidth of approximately 1 kHz. This resulted in a robust repetition rate locking with an Allan deviation of 330 Hz at a gate time of 1 s and a residual integrated timing jitter of 418 fs [3 Hz to 1 MHz] when referenced to a hydrogen maser. Along with reducing the size and improving the environmental adaptability of the OFC, our design can also decrease the power consumption of the system significantly. Our findings provide a new direction to the development of OFCs for various applications.