The principle of a Mamyshev oscillator depends on alternating spectral filtering between sections of spectral broadening by self-phase modulation. In the 2 µm wavelength range, this concept faces the difficulty that standard fibers are anomalous dispersive which limits the possible pulse energy to the pJ-regime without proper dispersion management. We applied ultra-high numerical aperture fibers with normal dispersion in order to achieve up-chirped pulses in an anomalous dispersive Thulium-doped gain fiber. With that design, we achieved mode-locked pulses with energies of 6.4 nJ and a compressed autocorrelation duration of 195 fs at a repetition rate of 16 MHz.
Recently, Mamyshev oscillators (MO) have attained a lot of attention, due to their generation of mode-locked pulses with outstanding output parameters in terms of output energy, spectral bandwidth and pulse duration. We present a MO with output pulse energies in the range of 0.5µJ, an optical spectrum ranging from 1010nm to 1060nm and an externally compressed autocorrelation duration of less than 100fs. This MO completely consists of commercially available standard step-index fibers. In order to handle the high pulse energies, we apply a few-mode gain fiber with a core-diameter of 20µm in the second arm of the oscillator.
We present the characteristics of a high-energy ultrafast Yb-fiber laser system, based on a Mamyshev oscillator and a subsequently arranged fiber amplifier stage. The Mamyshev oscillator emits pulses at a repetition rate of 11 MHz and pulse energies of 31 nJ. These pulses are spectrally filtered and amplified in a Yb-doped fiber up to 1 μJ pulse energy which could be temporally dechirped to less than 50 fs autocorrelation duration. We discuss the scaling as well as limiting options related to pulse energies and duration.
We present the application of the dispersion scan (d-scan) technique in order to fully characterize intensity and phase of ultrafast pulses compressed by a grating-prism (grism) compressor.
Ultrafast pulses are generated in an Yb-doped fiber oscillator, mode-locked by non-linear polarization evolution (NPE) and operating at a central wavelength of 1030 nm with a repetition rate of 50 MHz. These output pulses are stretched in a 150 m long fiber to roughly 50 ps and then amplified in an Yb-doped fiber to an average power of 150 mW. A grating-prism combination is used to compensate the second and third order dispersion that was applied to the pulse by the fiber material.
For the optimal compression of the pulse, information on its spectral and temporal phase is required. Therefore, the dispersion scan is applied. In this technique, second harmonic spectra of the pulse are generated and recorded for different amounts of dispersion compensation applied to the pulse by the grism compressor. Depending on the chirp of the pulse, the maximum of the generated second harmonic spectra shifts, leading to a characteristic trace.
The amount of dispersion is changed by varying the separation of the prisms within the compressor, while the relation of second and third order dispersion is kept almost constant. The separation is changed by a stepper motor in order to enable a fully automated recording of the spectra.
The spectral and temporal course and phase of the pulse are then retrieved from the d-scan trace by a genetic computer algorithm.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.