Sub two-cycle soliton-effect pulse compression at 800 nm in Photonic Crystal Fibers

The possibility of soliton self-compression of ultrashort laser pulses down to the few-cycle regime in photonic crystal fibers is numerically investigated. We show that efficient sub-two-cycle temporal compression of nanojoule-level 800 nm pulses can be achieved by employing short (typically 5-mm-long) commercially available photonic crystal fibers and pulse durations of around 100 fs, regardless of initial linear chirp, and without the need of additional dispersion compensation techniques. We envisage applications in a new generation of compact and efficient sub-two cycle laser pulse sources.Comment: 16 pages, 6 figure

Noise and stability of actively modelocked fiber lasers

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.Includes bibliographical references (leaves 162-174).The timing jitter of a modelocked laser is fundamentally limited by the amplified spontaneous emission in the laser cavity. While one cannot, even in principle, remove this source of noise, one does have control over the pulse timing by using filtering and modulation. In this thesis, we report on the advances made in developing the understanding of timing jitter and stability in actively modelocked soliton fiber lasers. The main achievements reported here are: the development of a theory for quantum-limited timing jitter for the cases of amplitude and phase modulation (AM and PM, respectively); identification of a set of characteristic coefficients governing the physics of pulse retiming that depend on the laser parameters; construction of an apparatus-including the development of harmonically modelocked soliton fiber lasers in both a ring and a sigma configuration-to measure the predicted coefficients; and residual phase-noise measurements of the quantum-limited timing jitter using homodyne detection. The measurements of the characteristic coefficients and the timing jitter were found to be in good agreement with the theory. In addition, a theory for the case of harmonic modelocking was developed, and it is shown that the supermodes reveal pulse-to-pulse correlation statistics and must be included in measurements and calculations of the timing jitter. For the case of uncorrelated timing jitter between different pulses in the laser cavity, the supermodes are predicted to have the same timing jitter spectrum as the baseband mode, and this is confirmed by measurements.(cont.) A scheme for reducing the timing jitter of a pulse train outside of the laser cavity using group-velocity dispersion and phase modulation is described, and it is shown theoretically that a reduction in the timing jitter is possible, but only at the expense of the carrier-frequency fluctuations. It is also shown that two-photon absorption in a semiconductor mirror structure prevented pulse dropouts in a short harmonically modelocked soliton fiber laser producing picosecond pulses at 2 GHz.by Matthew Edward Grein.Ph.D

Roadmap on ultrafast optics

Contains fulltext : 166150.pdf (publisher's version ) (Closed access

Noise-related polarization dynamics for femto and picosecond pulses in normal dispersion fibers

We report how the complex intra-pulse polarization dynamics of coherent optical wavebreaking and incoherent Raman amplification processes in all-normal dispersion (ANDi) fibers vary for femto and picosecond pump pulses. Using high temporal resolution vector supercontinuum simulations, we identify deterministic polarization dynamics caused by wavebreaking and self-phase modulation for femtosecond pulses and quasi-chaotic polarization evolution driven by Raman amplification of quantum noise for picosecond pulses. In contrast to cross-phase modulation instability, the Raman-based polarization noise has no power threshold and is reduced by aligning the higher energy polarization component with the lower index axis of the fiber. The degree of polarization stability is quantified using new time domain parameters that build on the spectrally averaged degree of coherence used in supercontinuum research to quantify the output spectral stability. We show that the spectral coherence is intrinsically linked to polarization noise, and that the noise will occur in both polarization maintaining (PM) and non-PM fibers, spanning a broad range of pulse energies, durations, and fiber birefringence values. This analysis provides an in-depth understanding of the nonlinear polarization dynamics associated with coherent and incoherent propagation in ANDi fibers

Fiber Optic Devices Pumped with Semiconductor Disk Lasers

The aim of this thesis is to investigate the advantages of pumping fiber optic oscillators utilizing a special type of lasers – semiconductor disk lasers. Relatively novel semiconductor disk laser technology offers low relative intensity noise levels combined with scalable output power, stable operation and nearly diffraction-limited beam quality valuable for an efficient fiber coupling (70- 90%). This pumping technique was applied for optical pumping of fiber lasers. Low-noise fiber Raman amplifier in co-propagation configuration for pump and signal was developed in the 1.3 μm spectral range. A hybrid Raman-bismuth-doped fiber amplifier scheme for an efficient pump light conversion was proposed and demonstrated. Semiconductor disk lasers operating at 1.29 μm and 1.48 μm were used as the pump sources for picosecond Raman fiber lasers at 1.38 and 1.6 μm. The 1.38 μm passively modelocked Raman fiber laser produced 1.97 ps pulses with a ring cavity configuration. The 1.6 μm linear cavity fiber laser with the integrated SESAM produced 2.7 ps output. A picosecond semiconductor disk laser followed by the ytterbium-erbium fiber amplifier offered supercontinuum generation spanning from 1.35 μm to 2 μm with an average power of 3.5 W. By utilizing a 1.15 μm semiconductor disk laser, a pulsed Ho3+-doped fiber lasers for a 2 μm spectral band were demonstrated. 118 nJ pulses at the repetition rate of 170 kHz and central wavelength of 2097 nm were produced by a holmium fiber laser Q-switched by a carbon nanotube saturable absorber. Sub-picosecond holmium-doped fiber laser modelocked with a broadband carbon nanotube saturable absorber and a SESAM were developed. Using the former saturable absorber, ultrashort pulse operation with the duration of ~ 890 fs in the 2030-2100 nm wavelength range was obtained. The results in the presented dissertation demonstrate the potential of the semiconductor disk laser technology for pumping fiber amplifiers and ultrafast lasers