Breathing solitons, i.e., dynamic dissipative solitons with oscillating pulse shape and energy caused by different mechanisms of spatiotemporal instabilities, have received considerable interest from the aspects of nonlinear science and potential applications. However, by far, the study of breathing solitons is still limited within the time scale of hundreds of cavity round trips, which ignores the slow dynamics. To fill this lacuna, we theoretically investigate a new type of vector dissipative soliton breathing regime and experimentally demonstrate this concept using mode-locked fiber lasers, which arise from the desynchronization of orthogonal states of polarization (SOPs) in the form of complex oscillations of the phase difference between the states. The dynamic evolution of polarization states of the vector breathings solitons takes the form of a trajectory connecting two quasi-equilibrium orthogonal SOPs on the surface of the Poincaré sphere. The dwelling time near each state is on the scale of a tenth of a thousand cavity round trip times that equals the breathing period, which is up to 2 orders of magnitude longer than that for common breathers. The obtained results can reveal concepts in nonlinear science and may unlock approaches to the flexible manipulation of laser waveforms toward various applications in spectroscopy and metrology.
This paper focuses on the quarter-wave plate design based on subwavelength high-index-contrast grating (HCG). The relationship among the equivalent refractive index of the HCG, the duty cycle of grating and the incident wavelength was obtained with the theory of effective medium and rigorous coupled wave analysis. By selecting the parameters and using the iterative algorithm proposed in this paper, quarter-wave plates with excellent performance can be obtained.
A miniature vibration sensor based on a compact microfiber probe is proposed and experimentally demonstrated. The microfiber probe is simply fabricated by snapping a multimode biconical microfiber in the fused tapering process. Vibration causes periodic bending and axial extension of microfiber probe, resulting in the change of phase difference between fundamental mode and high-order modes. The vibration signal can be obtained by demodulated the reflected light signal with fast Fourier transform. The experimental result shows that the vibration sensor not only can exactly measure the frequency of the applied sinusoidal vibration signal, but also has a wide frequency measurement range of 20 Hz-2 kHz. The advantages of compact size and high accuracy make the vibration sensor have great application prospects.
Ultrafast fiber laser has been widely used for spreading the extensive industrial applications and exploring the optics nonlinear dynamics. Here, we report a bidirectional fiber laser passively mode-locked by nonlinear polarization rotation (NPR) technique, supporting the emission of multi-state solitons. For the first time to the best of our knowledge, a Φ-shape auxiliary cavity based on chirped fiber Bragg grating (CFBG) is proposed to simultaneously introduce large anomalous and normal dispersion into the lasing oscillator. As a result, different dispersion distributions are achieved intra-cavity, respectively corresponding to counter propagating directions. Thus, conventional soliton (CS) and dissipative soliton (DS) are respectively generated in clockwise and counter-clockwise propagating directions. The results could benefit multifunctional ultrafast fiber laser system, which is potentially set for many practical applications as well as the study of soliton dynamics.
We demonstrated Erbium-doped mode-locked fiber lasers by using a chirped fiber Bragg grating (CFBG) as a dispersion managing element. Both conventional soliton and M-shape soliton pulses were achieved when the laser operates in the large anomalous and normal regime by controlling the direction of the CFBG, respectively.
In this paper, we have theoretically analyzed and experimentally demonstrated the spatial distribution of the radiation mode of 45° tilted fiber grating (TFG). The simulation results have shown the intensity distribution of the radiation mode along the fiber axis exhibited an exponential reduction. In experiment, we have observed the radiation mode pattern of a 5-mm long 45°TFG. The captured profiles along the radial direction and axial direction were in good agreement with the simulated results of the model.
A distributed vibration sensing technique using double-optical-pulse based on phase-sensitive optical time-domain reflectometry (ϕ-OTDR) and an ultraweak fiber Bragg grating (UWFBG) array is proposed for the first time. The single-mode sensing fiber is integrated with the UWFBG array that has uniform spatial interval and ultraweak reflectivity. The relatively high reflectivity of the UWFBG, compared with the Rayleigh scattering, gains a high signal-to-noise ratio for the signal, which can make the system achieve the maximum detectable frequency limited by the round-trip time of the probe pulse in fiber. A corresponding experimental ϕ-OTDR system with a 4.5 km sensing fiber integrated with the UWFBG array was setup for the evaluation of the system performance. Distributed vibration sensing is successfully realized with spatial resolution of 50 m. The sensing range of the vibration frequency can cover from 3 Hz to 9 kHz.
We demonstrate a high accuracy demodulation platform with a tunable Fabry-Perot filter (TFF) for twin-grating based fiber optic sensing network with hybrid TDM/FDM. The hybrid TDM/FDM scheme can improve the spatial resolution to centimeter but increases the requirement of high spectrum resolution. To realize the demodulation of the complex twin-grating spectrum, we adopt the TFF demodulation method and compensate the environmental temperature change and nonlinear effect through calibration FBGs. The performance of the demodulation module is tested by a temperature experiment. Spectrum resolution of 1pm is realized with precision of 2.5pm while the environmental temperature of TFF changes 9.3°C.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.