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Questions and Answers
What is the repetition rate achieved by the laser in the study?
What is the repetition rate achieved by the laser in the study?
What is the duration of the optical pulses at the highest repetition rate?
What is the duration of the optical pulses at the highest repetition rate?
3.6 ps
Standard active fibers exhibit high amplification.
Standard active fibers exhibit high amplification.
False
The cavity of the Er-Yb all-fiber laser consisted of a composite active fiber and a hybrid isolator-coupler-_______.
The cavity of the Er-Yb all-fiber laser consisted of a composite active fiber and a hybrid isolator-coupler-_______.
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What material was placed in the cavity to realize the mode-locking regime?
What material was placed in the cavity to realize the mode-locking regime?
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What application areas are mentioned for ultrashort pulse lasers?
What application areas are mentioned for ultrashort pulse lasers?
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Heavily doped phosphate fibers have poor splicing characteristics with standard optical components.
Heavily doped phosphate fibers have poor splicing characteristics with standard optical components.
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Lasers with a short length are typically created with a _____ cavity.
Lasers with a short length are typically created with a _____ cavity.
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What is the pulse repetition rate achieved in the Er-Yb all-fiber laser demonstration?
What is the pulse repetition rate achieved in the Er-Yb all-fiber laser demonstration?
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What material was used in the fiber laser cavity to realize the mode-locking regime?
What material was used in the fiber laser cavity to realize the mode-locking regime?
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What was the average output power of the optical pulses at the highest repetition rate?
What was the average output power of the optical pulses at the highest repetition rate?
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The length optimization of the laser cavity involved increasing the pulse repetition rate from 100 to _____ MHz.
The length optimization of the laser cavity involved increasing the pulse repetition rate from 100 to _____ MHz.
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Standard active fibers can achieve ultrashort pulses with a repetition rate higher than 250 MHz.
Standard active fibers can achieve ultrashort pulses with a repetition rate higher than 250 MHz.
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What is a significant disadvantage of heavily doped phosphate fibers?
What is a significant disadvantage of heavily doped phosphate fibers?
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What applications are in demand for lasers with sub-GHz and GHz ultrashort pulse repetition rates?
What applications are in demand for lasers with sub-GHz and GHz ultrashort pulse repetition rates?
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Study Notes
Er-Yb all-fiber laser with a repetition rate for ultrashort pulses of 300 MHz
- A short cavity passively mode-locked erbium-ytterbium fiber laser was optimized
- The cavity used a composite active fiber and a hybrid isolator-coupler-multiplexer
- Aerosol-synthesized single-walled carbon nanotubes were placed in the cavity to achieve mode-locking
- Pulse repetition rate increased from 100 to 298 MHz during length optimization
- At the highest repetition rate, pulses were 3.6 ps and average output power was 1.6 mW
Fiber Lasers for Research
- Fiber lasers are reliable tools in medicine, biology, and materials research
- Passive mode-locked (ML) fiber lasers are widely used for ultrashort pulse sources (USPs) in optical ADCs, materials processing, and supercontinuum generation
- Several passive ML strategies exist, including nonlinear polarization rotation, nonlinear loop mirrors, saturable absorbers (graphene, topological insulators, carbon nanotubes, SESAMs)
- Compact fiber lasers with sub-GHz and GHz USP repetition rates are in demand for applications in terahertz radiation sources, broadband telecommunication, high-resolution microscopy, and more
- High repetition rates can be achieved by reducing cavity length or using harmonic mode-locking
Short Cavity Fiber Lasers
- Short cavity lasers use Fabry-Perot (FP) cavities, which can be challenging with standard active fibers due to their low amplification
- Heavily doped phosphate fibers offer higher gain and thus shorter cavity lengths, enabling higher repetition rates
- However, these are susceptible to air degradation and require specialized splicing
- Ring cavities are an alternative to FP cavities, offering better all-fiber design stability, reduced losses, and better connectivity with standard optical components
Composite Erbium-Ytterbium-Doped Fiber (EYDF)
- Employ a phosphate glass core with a high concentration of Er/Yb ions and a silica glass cladding
- The "rod-in-tube" fabrication technique is used
- Improved thermomechanical properties and moisture stability compared to silicate glasses.
- Low content of residual OH-groups
Mode-Locking using SWCNTs
- Polymer-free thin films of aerosol-synthesized single-walled carbon nanotubes (SWCNTs) were used as a saturable absorber
- This avoids the degradation issues of CNTs in polymer matrices
- The composite fiber, hybrid element, and unique SWCNTs were successfully used to achieve a pulse repetition rate exceeding 250 MHz in an all-fiber ring cavity
Experimental Setup and Results
- Laser cavity length reduction from 1.93 m to 0.67 m enabled higher repetition rates
- At 298.5 MHz repetition rate, pulse duration of 2.3 ps, output power 1.64 mW, and a very high signal-to-noise ratio of 70 dB were achieved
- Harmonic mode-locking regimes were observed (e.g., doubled and tripled) but weren't stably measurable
- Different wavelengths (e.g. 1535nm, 1542 nm) were obtained
- The results show a strong potential for compact high-pulse repetition rate ultrashort pulse sources, using these composite fibers along with appropriate components, like the hybrid component, and SWCNTs.
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Description
This quiz explores the advancements in erbium-ytterbium fiber lasers, particularly focusing on their optimization for ultrashort pulse generation at high repetition rates. It discusses the technologies used, including mode-locking strategies and materials like carbon nanotubes that enhance laser performance. Suitable for students in optics and laser technology.
