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Mode-locked Lasers|7 Article(s)
Effect of spatial hole burning on a dual-wavelength mode-locked laser based on compactly combined dual gain media
Y. J. Huang, Y. S. Tzeng, H. H. Cho, and and Y. F. Chen
The effect of spatial hole burning (SHB) on dual-wavelength self-mode-locked lasers based on physically combined Nd:YVO4∕Nd:LuVO4 and Nd:YVO4∕Nd:KGW composite active medium is comparatively investigated. The length of the first Nd:YVO4 crystal is optimized to realize a highly compact and efficient TEM00-mode picosecond laser at 1.06 μm with optical conversion efficiency greater than 20%. When the SHB effect is enhanced by decreasing the separation between the input end mirror and the composite gain medium, it is experimentally found that not only the pulse duration monotonically decreases, but also the temporal behavior gradually displays a narrow-peak-on-a-pedestal shape for the Nd:YVO4∕Nd:LuVO4 scheme, while the multipulse operation can be obtained for the Nd:YVO4∕Nd:KGW configuration. These phenomena are further explored by numerically simulating mode-locked pulses from the experimentally measured optical spectra. The effect of spatial hole burning (SHB) on dual-wavelength self-mode-locked lasers based on physically combined Nd:YVO4∕Nd:LuVO4 and Nd:YVO4∕Nd:KGW composite active medium is comparatively investigated. The length of the first Nd:YVO4 crystal is optimized to realize a highly compact and efficient TEM00-mode picosecond laser at 1.06 μm with optical conversion efficiency greater than 20%. When the SHB effect is enhanced by decreasing the separation between the input end mirror and the composite gain medium, it is experimentally found that not only the pulse duration monotonically decreases, but also the temporal behavior gradually displays a narrow-peak-on-a-pedestal shape for the Nd:YVO4∕Nd:LuVO4 scheme, while the multipulse operation can be obtained for the Nd:YVO4∕Nd:KGW configuration. These phenomena are further explored by numerically simulating mode-locked pulses from the experimentally measured optical spectra.
Photonics Research
- Publication Date: Nov. 15, 2014
- Vol. 2, Issue 6, 06000161 (2014)
Bursts with shape-alterable pulses in a compact Tm-doped fiber laser with simultaneous active intracavity phase and intensity modulations
Xiong Wang, Pu Zhou, Xiaolin Wang, Hu Xiao, and and Zejin Liu
We present a compact Tm-doped fiber laser (TDFL) to generate pulse bursts at 1.92 μm based on phase and intensity modulations. A phase modulator (PM) and an intensity modulator (IM) were included in the linear TDFL cavity to perform the simultaneous active intracavity phase and intensity modulation. Stable pulse bursts have been achieved with tunable repetition rate in the range of 36–44 kHz (modulated by the PM) and duration of about 9.6 μs. The repetition rate of the individual pulse in a burst is about 9 MHz (modulated by the IM), and the pulse width is about 6 ns. By changing the IM signal’s repetition rate and duty cycle, different individual pulse shapes are obtained with pulse durations between 6 and 34 ns. We present a compact Tm-doped fiber laser (TDFL) to generate pulse bursts at 1.92 μm based on phase and intensity modulations. A phase modulator (PM) and an intensity modulator (IM) were included in the linear TDFL cavity to perform the simultaneous active intracavity phase and intensity modulation. Stable pulse bursts have been achieved with tunable repetition rate in the range of 36–44 kHz (modulated by the PM) and duration of about 9.6 μs. The repetition rate of the individual pulse in a burst is about 9 MHz (modulated by the IM), and the pulse width is about 6 ns. By changing the IM signal’s repetition rate and duty cycle, different individual pulse shapes are obtained with pulse durations between 6 and 34 ns.
Photonics Research
- Publication Date: Nov. 15, 2014
- Vol. 2, Issue 6, 06000172 (2014)
Soliton mode-locked fiber laser based on topological insulator Bi2Te3 nanosheets at 2 μm
Ke Yin, Bin Zhang, Lei Li, Tian Jiang, Xuanfeng Zhou, and Jing Hou
We reported diverse soliton operations in a thulium/holmium-doped fiber laser by taking advantage of a tapered fiber-based topological insulator (TI) Bi2Te3 saturable absorber (SA). The SA had a nonsaturable loss of ～53.5% and a modulation depth of 9.8%. Stable fundamentally mode-locked solitons at 1909.5 nm with distinct Kelly sidebands on the output spectrum, a pulse repetition rate of 21.5 MHz, and a measured pulse width of 1.26 ps were observed in the work. By increasing the pump power, both bunched solitons with soliton number up to 15 and harmonically mode-locked solitons with harmonic order up to 10 were obtained. To our knowledge, this is the first report of both bunched solitons and harmonically mode-locked solitons in a fiber laser at 2 μm region incorporated with TIs. We reported diverse soliton operations in a thulium/holmium-doped fiber laser by taking advantage of a tapered fiber-based topological insulator (TI) Bi2Te3 saturable absorber (SA). The SA had a nonsaturable loss of ～53.5% and a modulation depth of 9.8%. Stable fundamentally mode-locked solitons at 1909.5 nm with distinct Kelly sidebands on the output spectrum, a pulse repetition rate of 21.5 MHz, and a measured pulse width of 1.26 ps were observed in the work. By increasing the pump power, both bunched solitons with soliton number up to 15 and harmonically mode-locked solitons with harmonic order up to 10 were obtained. To our knowledge, this is the first report of both bunched solitons and harmonically mode-locked solitons in a fiber laser at 2 μm region incorporated with TIs.
Photonics Research
- Publication Date: Apr. 09, 2015
- Vol. 3, Issue 3, 03000072 (2015)
On-chip mode-locked laser diode structure using multimode interference reflectors
C.Gordon, R.Guzman, X.Leijtens, and G.Carpintero
We report, for the first time to our knowledge, an on-chip mode-locked laser diode (OCMLLD) that employs multimode interference reflectors to eliminate the need of facet mirrors to form the cavity. The result is an OCMLLD that does not require cleaved facets to operate, enabling us to locate this OCMLLD at any location within the photonic chip. This OCMLLD provides a simple source of optical pulses that can be inserted within a photonic integrated circuit chip for subsequent photonic signal processing operations within the chip (modulation, optical filtering, pulse rate multiplication, and so on). The device was designed using standardized building blocks of a generic active/passive InP technology platform, fabricated in a multi-project wafer run, and achieved mode-locking operation at its fundamental frequency, given the uncertainty at the design step of the optical length of these mirrors, critical to achieve colliding pulse mode-locked operation. We report, for the first time to our knowledge, an on-chip mode-locked laser diode (OCMLLD) that employs multimode interference reflectors to eliminate the need of facet mirrors to form the cavity. The result is an OCMLLD that does not require cleaved facets to operate, enabling us to locate this OCMLLD at any location within the photonic chip. This OCMLLD provides a simple source of optical pulses that can be inserted within a photonic integrated circuit chip for subsequent photonic signal processing operations within the chip (modulation, optical filtering, pulse rate multiplication, and so on). The device was designed using standardized building blocks of a generic active/passive InP technology platform, fabricated in a multi-project wafer run, and achieved mode-locking operation at its fundamental frequency, given the uncertainty at the design step of the optical length of these mirrors, critical to achieve colliding pulse mode-locked operation.
Photonics Research
- Publication Date: Jan. 15, 2015
- Vol. 3, Issue 1, 01000015 (2015)
Dual-wavelength rectangular pulse erbium-doped fiber laser based on topological insulator saturable absorber
Bo Guo, Yong Yao, Yan-Fu Yang, Yi-Jun Yuan, Lei Jin, Bo Yan, and Jian-Yu Zhang
We reported on the generation of the dual-wavelength rectangular pulse in an erbium-doped fiber laser (EDFL) with a topological insulator saturable absorber. The rectangular pulse could be stably initiated with pulse width from 13.62 to 25.16 ns and fundamental repetition rate of 3.54 MHz by properly adjusting the pump power and the polarization state. In addition, we verified that the pulse shape of the dual-wavelength rectangular pulse can be affected by the total net cavity dispersion in the fiber laser. Furthermore, by properly rotating the polarization controllers, the harmonic mode-locking operation of the dual-wavelength rectangular pulse was also obtained. The dual-wavelength rectangular pulse EDFL would benefit some potential applications, such as spectroscopy, biomedicine, and sensing research. We reported on the generation of the dual-wavelength rectangular pulse in an erbium-doped fiber laser (EDFL) with a topological insulator saturable absorber. The rectangular pulse could be stably initiated with pulse width from 13.62 to 25.16 ns and fundamental repetition rate of 3.54 MHz by properly adjusting the pump power and the polarization state. In addition, we verified that the pulse shape of the dual-wavelength rectangular pulse can be affected by the total net cavity dispersion in the fiber laser. Furthermore, by properly rotating the polarization controllers, the harmonic mode-locking operation of the dual-wavelength rectangular pulse was also obtained. The dual-wavelength rectangular pulse EDFL would benefit some potential applications, such as spectroscopy, biomedicine, and sensing research.
Photonics Research
- Publication Date: Apr. 17, 2015
- Vol. 3, Issue 3, 03000094 (2015)
Passive mode-locking in semiconductor lasers with saturable absorbers bandgap shifted through quantum well intermixing
Vincenzo Pusino, Michael J. Strain, and Marc Sorel
Passive mode-locking in semiconductor lasers in a Fabry–Perot configuration with a bandgap blueshift applied to the saturable absorber (SA) section has been experimentally characterized. For the first time a fully post-growth technique, quantum well intermixing, was adopted to modify the material bandgap in the SA section. The measurements showed not only an expected narrowing of the pulse width but also a significant expansion of the range of bias conditions generating a stable train of optical pulses. Moreover, the pulses from lasers with bandgap shifted absorbers presented reduced chirp and increased peak power with respect to the nonshifted case. Passive mode-locking in semiconductor lasers in a Fabry–Perot configuration with a bandgap blueshift applied to the saturable absorber (SA) section has been experimentally characterized. For the first time a fully post-growth technique, quantum well intermixing, was adopted to modify the material bandgap in the SA section. The measurements showed not only an expected narrowing of the pulse width but also a significant expansion of the range of bias conditions generating a stable train of optical pulses. Moreover, the pulses from lasers with bandgap shifted absorbers presented reduced chirp and increased peak power with respect to the nonshifted case.
Photonics Research
- Publication Date: Nov. 15, 2014
- Vol. 2, Issue 6, 06000186 (2014)
Generation of sub-100 fs pulses tunable from 1700 to 2100 nm from a compact frequency-shifted Er-fiber laser
Grzegorz Soboń, Tadeusz Martynkien, Karol Tarnowski, Paweł Mergo, and Jarosław Sotor
We report generation of sub-100 fs pulses tunable from 1700 to 2100 nm via Raman soliton self-frequency shift. The nonlinear shift occurs in a highly nonlinear fiber, which is pumped by an Er-doped fiber laser. The whole system is fully fiberized, without the use of any free-space optics. Thanks to its exceptional simplicity, the setup can be considered as an alternative to mode-locked Tm- and Ho-doped fiber lasers. We report generation of sub-100 fs pulses tunable from 1700 to 2100 nm via Raman soliton self-frequency shift. The nonlinear shift occurs in a highly nonlinear fiber, which is pumped by an Er-doped fiber laser. The whole system is fully fiberized, without the use of any free-space optics. Thanks to its exceptional simplicity, the setup can be considered as an alternative to mode-locked Tm- and Ho-doped fiber lasers.
Photonics Research
- Publication Date: Apr. 10, 2017
- Vol. 5, Issue 3, 03000151 (2017)
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