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Dissolution-and-reduction CVD synthesis of few-layer graphene on ultra-thin nickel film lifted off for mode-locking fiber lasers.

Peng KJ, Lin YH, Wu CL, Lin SF, Yang CY, Lin SM, Tsai DP, Lin GR - Sci Rep (2015)

Bottom Line: In contrast, the reflection-type SA only compresses the pulsewidth from 875 to 796 fs with corresponding spectral linewidth broadened from 2.2 to 3.3 nm.The reflection-type graphene mode-locker increases twice of its equivalent layer number to cause more insertion loss than the transmission-type one.Nevertheless, the reflection-type based saturable absorber system can generate stabilized soliton-like pulse easier than that of transmission-type system, because the nonlinearity induced self-amplitude modulation depth is simultaneously enlarged when passing through the graphene twice under the retro-reflector design.

View Article: PubMed Central - PubMed

Affiliation: Graduate Institute of Photonics and Optoelectronics, Department of Electrical Engineering, National Taiwan University (NTU), No.1, Sec. 4, Roosevelt Road, Taipei 106, Taiwan, Republic of China.

ABSTRACT
The in-situ dissolution-and-reduction CVD synthesized few-layer graphene on ultra-thin nickel catalyst film is demonstrated at temperature as low as 550 °C, which can be employed to form transmission-type or reflection-type saturable absorber (SA) for mode-locking the erbium-doped fiber lasers (EDFLs). With transmission-type graphene SA, the EDFL shortens its pulsewidth from 483 to 441 fs and broadens its spectral linewidth from 4.2 to 6.1 nm with enlarging the pumping current from 200 to 900 mA. In contrast, the reflection-type SA only compresses the pulsewidth from 875 to 796 fs with corresponding spectral linewidth broadened from 2.2 to 3.3 nm. The reflection-type graphene mode-locker increases twice of its equivalent layer number to cause more insertion loss than the transmission-type one. Nevertheless, the reflection-type based saturable absorber system can generate stabilized soliton-like pulse easier than that of transmission-type system, because the nonlinearity induced self-amplitude modulation depth is simultaneously enlarged when passing through the graphene twice under the retro-reflector design.

No MeSH data available.


Passively mode-locked EDFL performances by transmission-type graphene saturable absorber.(a) The photograph of patchcord end-face with and without hydrogen-free and low temperature synthesized graphene on the surface. (b) The oscilloscope trace of passively mode-locked EDFL. (c) and (d) The optical spectra and autocorrelation traces of transmission-type passively mode-locked EDFL system under different pumping current. (e) The varied pulsewidth and FWHM of transmission-type passively mode-locked EDFL system under different pumping current. (f) The time-bandwidth products of the transmission-type passively mode-locked EDFL system under different pumping current.
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f2: Passively mode-locked EDFL performances by transmission-type graphene saturable absorber.(a) The photograph of patchcord end-face with and without hydrogen-free and low temperature synthesized graphene on the surface. (b) The oscilloscope trace of passively mode-locked EDFL. (c) and (d) The optical spectra and autocorrelation traces of transmission-type passively mode-locked EDFL system under different pumping current. (e) The varied pulsewidth and FWHM of transmission-type passively mode-locked EDFL system under different pumping current. (f) The time-bandwidth products of the transmission-type passively mode-locked EDFL system under different pumping current.

Mentions: Figure 2a compares the photographs of an SMF connector without and with the few-layer graphene adhered on its end-face, which clearly show the adhered few-layer graphene observed from microscopic images of core and cladding surfaces on the connector end-face. The core area of the connector is remarked by using red-dash circle and the other area at the end-face is the cladding region. According to the photographs, the core area was not covered by any contaminates or residues. To prevent unnecessary scattering and insertion loss caused by those contaminates or residues, each patchcord end-face is checked before experiments so as to minimize the unexpected loss. Although some non-negligible contaminates or residues may attach on the cladding area, the EDFL performances will not be affected accordingly. Under mode-locking with the transmission-type few-layer graphene saturable absorber, the pulse-train depicted in Fig. 2b for the EDFL with a cavity length of 7.43 m reveals the round-trip time and repetition frequency of 35 ns and 28.57 MHz, respectively. The optical spectra of the transmission-type graphene mode-locked EDFL with its central wavelength located around 1572 ± 0.5 nm at different pumping conditions are shown in Fig. 2c. That indicates the pumping power does not affect the location of central wavelength too much in transmission type passively mode-locked EDFL system. The spectral linewidth broadens from 4.2 to 6.1 nm with enlarging the pumping currents from 200 to 900 mA, and the soliton is formed with significant Kelly sidebands at pumping current larger than 400 mA. The higher pumping level is required for obtaining the soliton from the few-layer graphene saturable absorber mode-locked EDFL, which is mainly attributed to the larger linear loss of the 6–7 layer graphene added into the EDFL cavity so as to put off the soliton mode-locking threshold.


Dissolution-and-reduction CVD synthesis of few-layer graphene on ultra-thin nickel film lifted off for mode-locking fiber lasers.

Peng KJ, Lin YH, Wu CL, Lin SF, Yang CY, Lin SM, Tsai DP, Lin GR - Sci Rep (2015)

Passively mode-locked EDFL performances by transmission-type graphene saturable absorber.(a) The photograph of patchcord end-face with and without hydrogen-free and low temperature synthesized graphene on the surface. (b) The oscilloscope trace of passively mode-locked EDFL. (c) and (d) The optical spectra and autocorrelation traces of transmission-type passively mode-locked EDFL system under different pumping current. (e) The varied pulsewidth and FWHM of transmission-type passively mode-locked EDFL system under different pumping current. (f) The time-bandwidth products of the transmission-type passively mode-locked EDFL system under different pumping current.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4556966&req=5

f2: Passively mode-locked EDFL performances by transmission-type graphene saturable absorber.(a) The photograph of patchcord end-face with and without hydrogen-free and low temperature synthesized graphene on the surface. (b) The oscilloscope trace of passively mode-locked EDFL. (c) and (d) The optical spectra and autocorrelation traces of transmission-type passively mode-locked EDFL system under different pumping current. (e) The varied pulsewidth and FWHM of transmission-type passively mode-locked EDFL system under different pumping current. (f) The time-bandwidth products of the transmission-type passively mode-locked EDFL system under different pumping current.
Mentions: Figure 2a compares the photographs of an SMF connector without and with the few-layer graphene adhered on its end-face, which clearly show the adhered few-layer graphene observed from microscopic images of core and cladding surfaces on the connector end-face. The core area of the connector is remarked by using red-dash circle and the other area at the end-face is the cladding region. According to the photographs, the core area was not covered by any contaminates or residues. To prevent unnecessary scattering and insertion loss caused by those contaminates or residues, each patchcord end-face is checked before experiments so as to minimize the unexpected loss. Although some non-negligible contaminates or residues may attach on the cladding area, the EDFL performances will not be affected accordingly. Under mode-locking with the transmission-type few-layer graphene saturable absorber, the pulse-train depicted in Fig. 2b for the EDFL with a cavity length of 7.43 m reveals the round-trip time and repetition frequency of 35 ns and 28.57 MHz, respectively. The optical spectra of the transmission-type graphene mode-locked EDFL with its central wavelength located around 1572 ± 0.5 nm at different pumping conditions are shown in Fig. 2c. That indicates the pumping power does not affect the location of central wavelength too much in transmission type passively mode-locked EDFL system. The spectral linewidth broadens from 4.2 to 6.1 nm with enlarging the pumping currents from 200 to 900 mA, and the soliton is formed with significant Kelly sidebands at pumping current larger than 400 mA. The higher pumping level is required for obtaining the soliton from the few-layer graphene saturable absorber mode-locked EDFL, which is mainly attributed to the larger linear loss of the 6–7 layer graphene added into the EDFL cavity so as to put off the soliton mode-locking threshold.

Bottom Line: In contrast, the reflection-type SA only compresses the pulsewidth from 875 to 796 fs with corresponding spectral linewidth broadened from 2.2 to 3.3 nm.The reflection-type graphene mode-locker increases twice of its equivalent layer number to cause more insertion loss than the transmission-type one.Nevertheless, the reflection-type based saturable absorber system can generate stabilized soliton-like pulse easier than that of transmission-type system, because the nonlinearity induced self-amplitude modulation depth is simultaneously enlarged when passing through the graphene twice under the retro-reflector design.

View Article: PubMed Central - PubMed

Affiliation: Graduate Institute of Photonics and Optoelectronics, Department of Electrical Engineering, National Taiwan University (NTU), No.1, Sec. 4, Roosevelt Road, Taipei 106, Taiwan, Republic of China.

ABSTRACT
The in-situ dissolution-and-reduction CVD synthesized few-layer graphene on ultra-thin nickel catalyst film is demonstrated at temperature as low as 550 °C, which can be employed to form transmission-type or reflection-type saturable absorber (SA) for mode-locking the erbium-doped fiber lasers (EDFLs). With transmission-type graphene SA, the EDFL shortens its pulsewidth from 483 to 441 fs and broadens its spectral linewidth from 4.2 to 6.1 nm with enlarging the pumping current from 200 to 900 mA. In contrast, the reflection-type SA only compresses the pulsewidth from 875 to 796 fs with corresponding spectral linewidth broadened from 2.2 to 3.3 nm. The reflection-type graphene mode-locker increases twice of its equivalent layer number to cause more insertion loss than the transmission-type one. Nevertheless, the reflection-type based saturable absorber system can generate stabilized soliton-like pulse easier than that of transmission-type system, because the nonlinearity induced self-amplitude modulation depth is simultaneously enlarged when passing through the graphene twice under the retro-reflector design.

No MeSH data available.