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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.

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Adiabatic soliton spectral compression in a dispersion-increasing fiber is demonstrated both numerically and experimentally. We show a positively-chirped pulse provides better spectral compression in a dispersion-increasing fiber with 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 m. A 30 nm wavelength tuning ability is experimentally achieved.Coherent optical sources with high spectral brightness and wide wavelength tuning range are highly desirable in spectroscopic applications, nonlinear microscopy, as well as wavelength-swept optical coherence tomography. The spectral brightness of a wideband optical source can be effectively enhanced through the redistribution of the source energy into a narrower spectral range. A solution is to perform spectral compression. The spectral narrowing effect was first explained for a negatively-chirped optical pulse propagating in optical fibers in the normal dispersive regime [1,2]. It was demonstrated later, chirped optical pulses within standard single-mode fiber [3,4] and photonic crystal fiber [5,6] with anomalous dispersions were also capable of achieving spectral compression. Such spectral narrowing effects have also been observed in normal dispersive gain fiber [7] and photonic crystal fiber [8]. Recently, a comb-profile fiber was used to demonstrate adiabatic soliton spectral compression with a compression ratio up to 26 [9]. However, extreme care in the design and fusion splicing among nineteen concatenations of standard single-mode and dispersion shifted fibers were required.While successfully observed in the above works, only a few works demonstrated spectral compressions with wide wavelength tuning abilities. In Ref.[9], wavelength tuning was achieved using different input pulse wavelengths rather than during the spectral compression process. In Ref.[10], soliton self-frequency shift was utilized to realize wide (~300 nm) wavelength tunable spectral compression in a highly nonlinear photonic crystal fiber, with spectral compression ratio of 6.5.Dispersion-decreasing fiber, in which a single fiber segment with gradual dispersion ramp is realized during fiber drawing process, has been widely adopted to achieve adiabatic soliton temporal compression [11] and finds many applications in coherent communications [12] and optical arbitrary waveform generations [13]. Implementing the dispersion-decreasing fiber reversely, a dispersion-increasing fiber (DIF) can be obtained and should enable a straightforward means in accomplishing adiabatic soliton spectral compression. However, such simple approach has not been realized to our best knowledge.In this Letter, the feasibility of adiabatic soliton spectral compression in a DIF is first assessed numerically. We demonstrate the first (to the best knowledge) experimental spectral compression in a 1-km dispersion flattened DIF. We show a positively-chirped pulse can obtain a larger spectral compression ratio in a DIF with ...

Based on the frequency-to-time mapping approach, we generate frequency-modulated millimeter-wave (MMW) pulses with central frequencies up to the W-band by a shaped optical pulse excitation of an MMW photonic transmitter with an ultrawide band photodiode as its key component. A coherent detection is achieved via a terahertz time-domain spectroscopic setup. Two different kinds of chirped MMW waveforms are generated; one is a linearly chirped sinusoidal pulse and the other is produced by a frequency-stepped modulation. Through appropriate optical spectral design, the frequency-chirped MMW pulses with instantaneous frequencies sweeping from 120 to 60 GHz, and a time-bandwidth product of ∼25 is experimentally demonstrated.Index Terms-Millimeter wave (MMW), photonic transmitter (PT), pulse shaping, terahertz (THz).