Highly efficient femtosecond pulse stretching by tailoring cavity dispersion in erbium fiber lasers with an intracavity short-pass edge filter.

We demonstrate highly efficient pulse stretching in Er(3+)-doped femtosecond mode-locked fiber lasers by tailoring cavity dispersion using an intracavity short-pass edge filter. The cavity dispersion is preset at around zero to obtain the shortest pulsewidth. When the cutoff wavelength of the short-pass edge filter is thermo-optically tuned to overlap the constituting spectral components of mode-locked pulses, large negative waveguide dispersion is introduced by the steep cutoff slope and the total cavity dispersion is moved to normal dispersion regime to broaden the pulsewidth. The time-bandwidth product of the mode-locked pulse increases with the decreasing temperature at the optical liquid surrounding the short-pass edge filter. Pulse stretch ratio of 3.53 (623.8 fs/176.8 fs) can be efficiently achieved under a temperature variation of 4 °C.

Wavelength-tunable spectral compression in a dispersion-increasing fiber.

We demonstrate, both numerically and experimentally, adiabatic soliton spectral compression in a dispersion-increasing fiber (DIF). We show that a positively chirped pulse provides better spectral compression in a DIF with a large anomalous dispersion ramp. An experimental spectral compression ratio of 15.5 is obtained using 350 fs positively chirped input pulse centered at 1.5 µm. A 30 nm wavelength tuning ability is experimentally achieved.

Forty-photon-per-pulse spectral phase retrieval by shaper-assisted modified interferometric field autocorrelation.

We retrieve the spectral phase of 400 fs pulses at 1560 nm with 5.2 aJ coupled pulse energy (40 photons) by the modified interferometric field autocorrelation method, using a pulse shaper and a 5 cm long periodically poled lithium niobate waveguide. The carrier-envelope phase control of the shaper can reduce the fringe density of the interferometric trace and permits longer lock-in time constants, achieving a sensitivity of 2.7×10(-9) mW(2) (40 times better than the previous record for self-referenced nonlinear pulse measurement). The high stability of the pulse shaper allows for accurate and reproducible measurements of complicated spectral phases.

Generation and delivery of 1-ps optical pulses with ultrahigh repetition-rates over 25-km single mode fiber by a spectral line-by-line pulse shaper.

A spectral line-by-line pulse shaper is used to experimentally generate and deliver ~1 ps optical pulses of 31~124 GHz repetition-rates over 25.33 km single-mode fiber without dispersion-compensating fiber. The correlation of such delivery capability to temporal Talbot effect is experimentally demonstrated. Incorporating shaper periodic phase control, the repetition-rates of these~1 ps optical pulses are further multiplied up to 496 GHz and delivered over 25.33 km single-mode fiber.