The dynamics of three-dimensional (3D) dissipative solitons originated from spatiotemporal interactions share many common characteristics with other multi-dimensional phenomena. Unveiling the dynamics of 3D solitons thus permits new routes for tackling multidisciplinary nonlinear problems and exploiting their instabilities. However, this remains an open challenge, as they are multi-dimensional, stochastic and non-repeatable. Here, we report the real-time speckle-resolved spectral-temporal dynamics of a 3D soliton laser using a single-shot multispeckle spectral-temporal technology that leverages optical time division multiplexing and photonic time stretch. This technology enables the simultaneous observation on multiple speckle grains to provide long-lasting evolutionary dynamics on the planes of cavity time (t) – roundtrip and spectrum (λ) – roundtrip. Various non-repeatable speckly-diverse spectral-temporal dynamics are discovered in both the early and established stages of the 3D soliton formation.

An experiment for studying laser self-guiding has been carried out for the high power ultrashort pulse laser interaction with an underdense plasma slab. Formation of an extremely long plasma channel and its bending are observed when the laser pulse power is much higher than the critical power for relativistic self-focusing. The long self-guiding channel formation is accompanied by electron acceleration with a low transverse emittance and high electric current. Particle-in-cell simulations show that laser bending occurs when the accelerated electrons overtake the laser pulse and modify the refractive index in the region in front of the laser pulse.

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.