We experimentally demonstrate a cascaded generation of a conventional dissipative soliton (DS) at 1020 nm and Raman dissipative solitons (RDS) of the first (1065 nm) and second (1115 nm) orders inside a common fiber laser cavity. The generated high-energy pulses are shown to be linearly-chirped and compressible to 200-300 fs durations for all wavelengths. Moreover, the pulses are mutually coherent that has been confirmed by efficient coherent combining exhibiting ~75 fs and <40 fs interference fringes within the combined pulse envelope of a DS with the first-order RDS and the second-order RDS respectively. The numerical simulation was performed with sinusoidal (soft) and step-like (hard) spectral filters and took into account the discreetness of the laser elements. Shown that even higher degree of coherence and shorter pulses could be achieved with hard spectral filtering. This approach opens the door towards cascaded generation of multiple coherent dissipative solitons in a broad spectral range (so-called dissipative soliton comb). The demonstrated source of coherent dissipative solitons can improve numerous areas such as frequency comb generation, pulse synthesis, biomedical imaging and the generation of coherent mid-infrared supercontinuum.
A structural health monitoring system based on optical sensors has been developed and installed on the indoor soccer arena "Zarya" in Novosibirsk. The system integrates 119 fiber optic sensors: 85 strain, 32 temperature and 2 displacement sensors. In addition, total station is used for measuring displacement in 45 control points. All of the constituents of the supporting structure are subjects for monitoring: long-span frames with under floor ties, connections, purlins and foundation.
We report on the experimental realization of a highly-chirped dissipative soliton (DS) oscillator with all-fiber cavity consisting of a short single-mode fiber part (for mode locking via nonlinear polarization evolution) and a long PM fiber part (for generation of highly-chirped DS) that enabled to increase cavity length to <i>L</i> ~ 90 m. Stable DS pulses dechirped to ~ 200 fs are generated with maximum energy of ~ 20 nJ. The energy limit is shown to be defined by the onset of Raman conversion of the DS spectrum. The Stokes pulse reaching comparable energy inside the cavity and does not break the soliton stability. Higher DS energy is possible by means of a core enlargement, corresponding experiments are also performed.