Wavelength-tunable spectral compression in a dispersion-increasing fiber

Abstract

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 ...

Soliton control by a weak dispersive pulse

“…As a consequence the soliton experiences a different value of dispersion and so has to adjust its duration following the conditions required for soliton-like propagation. The scenario is similar to the one occurring in a dispersion-varying fiber, be it a dispersion-decreasing fiber [11] or a dispersion-increasing fiber [12]. In such fibers indeed the soliton-like pulse undergoes a change of its width following the change of the value of dispersion.…”

Modeling Frequency Comb Sources

“…Nonlinear spectral compression adopted in the cavity to reduce the filtering loss and enhance the power efficiency was proposed theoretically in [113] and experimentally demonstrated in [27]. Spectrum compression in fibers has been discussed for more than two decades [114][115][116]. The spectrum can be greatly compressed in passive fiber, especially with dispersion increasing fiber to support self-similar spectral compression, which is the inversion of self-similar pulse compression [116][117][118].…”

“…Spectrum compression in fibers has been discussed for more than two decades [114][115][116]. The spectrum can be greatly compressed in passive fiber, especially with dispersion increasing fiber to support self-similar spectral compression, which is the inversion of self-similar pulse compression [116][117][118]. But the fiber length required for large compression ratio is too long for a laser cavity.…”

All-fiber spectral compression and pedestal suppression in a two-stage structure employing a high nonlinear fiber interconnected with a high nonlinear fiber-nonlinear optical loop mirror

“…To the best of our knowledge, only a few works to date have focused on spectral pedestal elimination. 10,11 In Ref. 11, a comb-like dispersion profiled fiber composed of 19 concatenations of standard single-mode fibers (SMF) and dispersion shifting fibers is applied to keep adiabatic soliton propagation during its spectral compression, so that the spectral pedestal is largely suppressed.…”