Abstract
We investigated both experimentally and numerically self-phase modulation-induced spectrum compression dynamics of negatively chirped picosecond Gaussian pulses in the low-loss dispersion-shifted telecom fiber near its zero dispersion wavelength (ZDW). It was experimentally observed linearly interpolated monotonous increase in spectrum compression ratio (SCR) with negative chirp growth of the incident pulse in the range from −5.9 to −91.9. According to numerical simulations, despite its small values in the vicinity of ZDW, fiber dispersion limits both SCR growth and spectrum compression quality expressed in terms of time-bandwidth product value and energy confinement ratio at larger chirp values (|C| > 100), in a combined action with self-phase modulation (SPM). Having optimized fiber length and pulse energy, we achieved record 49.2-fold spectrum compression of 38.3-ps, 2.08 nJ negatively chirped Gaussian pulses with compressed spectrum FWHM of 0.23 nm and a50% energy confinement at 1560 nm wavelength, leading to a13.3-times spectral brightness magnification. We believe that results obtained can be promising for ultra-short pulse laser systems development with enhanced spectral brightness.
Highlights
Ultra-short pulse (USP) laser sources become indispensable tools for various applications in science, medicine and industry [1], [2]
We investigated both experimentally and numerically self-phase modulationinduced spectrum compression dynamics of negatively chirped picosecond Gaussian pulses in the low-loss dispersion-shifted telecom fiber near its zero dispersion wavelength (ZDW)
Compressed peaks were fitted with suitable Gaussian functions to retrieve their 3-dB widths ( λ) and further calculate energy confinement ratio (η) and time-bandwidth product (TBP) values
Summary
Ultra-short pulse (USP) laser sources become indispensable tools for various applications in science, medicine and industry [1], [2]. One possible approach to the problem of transform-limited narrow-bandwidth flexibly tunable pulse generation relies on a self-phase modulation (SPM) governed spectrum compression of seed femtosecond pulse (with hyperbolic secant or Gaussian envelopes) negatively pre-chirped either with external phase modulation [15] or in the dispersive element such as optical fiber [16], [17], prism [18], [19] or diffraction grating pair [20], [21] with simultaneous stretching up to picosecond durations, followed by their propagation through a fiber in the strongly nonlinear regime This approach allows to take advantage of outstanding performance inherent to well-elaborated femtosecond fiber oscillators, and to retrieve nearly transform-limited picosecond pulses with continuously tunable durations directly at the fiber out, which is quite beneficial in comparison with solid-state mode-locked USP sources (e.g., YAG family lasers) routinely generating narrowband picosecond pulses with fixed spectral widths. The issue of coherent narrowband spectrum applications is much wider than a problem of transform-limited picosecond pulse generation that can be realized in a mode-locked fiber laser [25] as well as with a narrow-bandwidth filter and the subsequent amplifier implementation
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
