We demonstrate a Q-switched Raman fiber laser using molybdenum disulfide （MoS2） as a saturable absorber （SA）. The SA is assembled by depositing a mechanically exfoliated MoS2 onto a fiber ferrule facet before it i...We demonstrate a Q-switched Raman fiber laser using molybdenum disulfide （MoS2） as a saturable absorber （SA）. The SA is assembled by depositing a mechanically exfoliated MoS2 onto a fiber ferrule facet before it is matched with another clean ferrule via a connector. It is inserted in a Raman fiber laser cavity with a total cavity length of about 8kin to generate a Q-switching pulse train operating at 1560.2nm. A 7.7-kin-long dispersion compensating fiber with 584 ps.nm-i km-1 of dispersion is used as a nonlinear gain medium. As the pump power is increased from 395 m W to 422 m W, the repetition rate of the Q-switching pulses can be increased from 132.7 to 137.4 kHz while the pulse width is concurrently decreased from 3.35μs to 3.03μs. The maximum pulse energy of 54.3 nJ is obtained at the maximum pump power of 422 roW. These results show that the mechanically exfoliated MoS2 SA has a great potential to be used for pulse generation in Raman fiber laser systems.展开更多
We report an efficient power tapping device working in near infra-red (800 nm) wavelength region based on UV-in- scribed 45° tilted fiber grating (45°-TFG) structure. Five 45°-TFGs were UV-inscribed in ...We report an efficient power tapping device working in near infra-red (800 nm) wavelength region based on UV-in- scribed 45° tilted fiber grating (45°-TFG) structure. Five 45°-TFGs were UV-inscribed in hydrogenated PS750 fiber using a custom-designed phase mask with different grating lengths of 3 mm, 5 mm, 9 mm, 12 mm and 15 mm, showing polarization dependent losses (PDLs) of 1 dB, 3 dB, 7 dB, 10 dB and 13 dB, respectively. The power side-tapping efficiency is clearly depending on the grating strength. It has been identified that the power tapping efficiency increases with the grating strength and deceases along the grating length. The side-tapped power profile has also been examined in azimuthal direction, showing a near-Gaussian distribution. These experimental results clearly demonstrated that 45°- TFGs may be used as in-fiber power tapping devices for applications requiring in-line signal monitoring.展开更多
We propose a transfer-learning multi-input multi-output(TL-MIMO)scheme to significantly reduce the required training complexity for converging the equalizers in mode-division multiplexing(MDM)systems.Based on a built ...We propose a transfer-learning multi-input multi-output(TL-MIMO)scheme to significantly reduce the required training complexity for converging the equalizers in mode-division multiplexing(MDM)systems.Based on a built three-mode(LP01,LP11a,and LP11b)multiplexed experimental system,we thoughtfully investigate the TL-MIMO performances on the three-typed data,collecting from different sampling times,launching optical powers,and inputting optical signal-to-noise ratios(OSNRs).A dramatic reduction of approximately 40%–83.33%in the required training complexity is achieved in all three scenarios.Furthermore,the good stability of TL-MIMO in both the launched powers and OSNR test bands has also been proved.展开更多
Bidirectional ultrafast fiber lasers present an attractive solution,enabling the generation of two mutually coherent ultrashort pulse trains in a simple and turnkey system.Still,the lack of a comprehensive numerical m...Bidirectional ultrafast fiber lasers present an attractive solution,enabling the generation of two mutually coherent ultrashort pulse trains in a simple and turnkey system.Still,the lack of a comprehensive numerical model describing steady-state bidirectional generation,and even less ultrafast soliton breakdowns and collisions,is obstructing the achievement of the performance compared with unidirectional lasers.In this paper,we have experimentally investigated real-time build-up dynamics of counter-propagating solitons in an ultrafast ring Er-doped fiber laser via the dispersive Fourier transform methodology.We parade that counter-propagating pulses experience independent build-up dynamics from modulation instability,undergoing breathing dynamics and diverging subordinate pulse structure formation and annihilation to a stable bidirectional pulse train.Yet,the interaction of pulses in the cavity presents the key underlying phenomenon driving formation evolution distinct from unidirectional pulse build-up.Our findings will provide physical foundations for bidirectional ultrafast fiber laser design to carry forward their application.展开更多
The singlemode-multimode-singlemode(SMS)fiber structure for a heart rate monitoring is proposed and developed.An artificial electrocardiogram(ECG)signal is used to simulate the heart pulse at different rates ranging f...The singlemode-multimode-singlemode(SMS)fiber structure for a heart rate monitoring is proposed and developed.An artificial electrocardiogram(ECG)signal is used to simulate the heart pulse at different rates ranging from 50 beats per minute(bpm)to 200 bpm.The SMS fiber structure is placed at the center of a loudspeaker and it senses the vibration of the pulse.The vibration of the pulse signal applied to the SMS fiber structure changes the intensity of the optical output power.The proposed sensor shows a linear frequency of the heart rate sensing range that matches well with the relevant heart rate from the artificial ECG.This work shows the capability of the SMS fiber structure monitoring the heart rate frequencies for a long term,high stability realization,and reproducibility,and being suitable for the observation in hospitals as well as in other environments.展开更多
文摘We demonstrate a Q-switched Raman fiber laser using molybdenum disulfide （MoS2） as a saturable absorber （SA）. The SA is assembled by depositing a mechanically exfoliated MoS2 onto a fiber ferrule facet before it is matched with another clean ferrule via a connector. It is inserted in a Raman fiber laser cavity with a total cavity length of about 8kin to generate a Q-switching pulse train operating at 1560.2nm. A 7.7-kin-long dispersion compensating fiber with 584 ps.nm-i km-1 of dispersion is used as a nonlinear gain medium. As the pump power is increased from 395 m W to 422 m W, the repetition rate of the Q-switching pulses can be increased from 132.7 to 137.4 kHz while the pulse width is concurrently decreased from 3.35μs to 3.03μs. The maximum pulse energy of 54.3 nJ is obtained at the maximum pump power of 422 roW. These results show that the mechanically exfoliated MoS2 SA has a great potential to be used for pulse generation in Raman fiber laser systems.
文摘We report an efficient power tapping device working in near infra-red (800 nm) wavelength region based on UV-in- scribed 45° tilted fiber grating (45°-TFG) structure. Five 45°-TFGs were UV-inscribed in hydrogenated PS750 fiber using a custom-designed phase mask with different grating lengths of 3 mm, 5 mm, 9 mm, 12 mm and 15 mm, showing polarization dependent losses (PDLs) of 1 dB, 3 dB, 7 dB, 10 dB and 13 dB, respectively. The power side-tapping efficiency is clearly depending on the grating strength. It has been identified that the power tapping efficiency increases with the grating strength and deceases along the grating length. The side-tapped power profile has also been examined in azimuthal direction, showing a near-Gaussian distribution. These experimental results clearly demonstrated that 45°- TFGs may be used as in-fiber power tapping devices for applications requiring in-line signal monitoring.
基金supported by the National Key R&D Program of China(No.2018YFB1801001)the Royal Society International Exchange Grant(No.IEC\NSFC\211244).
文摘We propose a transfer-learning multi-input multi-output(TL-MIMO)scheme to significantly reduce the required training complexity for converging the equalizers in mode-division multiplexing(MDM)systems.Based on a built three-mode(LP01,LP11a,and LP11b)multiplexed experimental system,we thoughtfully investigate the TL-MIMO performances on the three-typed data,collecting from different sampling times,launching optical powers,and inputting optical signal-to-noise ratios(OSNRs).A dramatic reduction of approximately 40%–83.33%in the required training complexity is achieved in all three scenarios.Furthermore,the good stability of TL-MIMO in both the launched powers and OSNR test bands has also been proved.
基金Royal Academy of Engineering and Global Challenges Research FundH2020 Marie Sklodowska-Curie Actions(COFUND-MULTIPLY).
文摘Bidirectional ultrafast fiber lasers present an attractive solution,enabling the generation of two mutually coherent ultrashort pulse trains in a simple and turnkey system.Still,the lack of a comprehensive numerical model describing steady-state bidirectional generation,and even less ultrafast soliton breakdowns and collisions,is obstructing the achievement of the performance compared with unidirectional lasers.In this paper,we have experimentally investigated real-time build-up dynamics of counter-propagating solitons in an ultrafast ring Er-doped fiber laser via the dispersive Fourier transform methodology.We parade that counter-propagating pulses experience independent build-up dynamics from modulation instability,undergoing breathing dynamics and diverging subordinate pulse structure formation and annihilation to a stable bidirectional pulse train.Yet,the interaction of pulses in the cavity presents the key underlying phenomenon driving formation evolution distinct from unidirectional pulse build-up.Our findings will provide physical foundations for bidirectional ultrafast fiber laser design to carry forward their application.
基金supported by the Directorate of Research and Community Service-Ministry of ResearchTechnology and Higher Education,Republic of Indonesia(Grant Nos.6/E/KPT/2019 and 954/PKS/ITS/2019).
文摘The singlemode-multimode-singlemode(SMS)fiber structure for a heart rate monitoring is proposed and developed.An artificial electrocardiogram(ECG)signal is used to simulate the heart pulse at different rates ranging from 50 beats per minute(bpm)to 200 bpm.The SMS fiber structure is placed at the center of a loudspeaker and it senses the vibration of the pulse.The vibration of the pulse signal applied to the SMS fiber structure changes the intensity of the optical output power.The proposed sensor shows a linear frequency of the heart rate sensing range that matches well with the relevant heart rate from the artificial ECG.This work shows the capability of the SMS fiber structure monitoring the heart rate frequencies for a long term,high stability realization,and reproducibility,and being suitable for the observation in hospitals as well as in other environments.
