Tailoring the properties of the driving laser to the need of applications often requires compromises among laser stability,high peak and average power levels,pulse duration,and spectral bandwidth.For instance,spectros...Tailoring the properties of the driving laser to the need of applications often requires compromises among laser stability,high peak and average power levels,pulse duration,and spectral bandwidth.For instance,spectroscopy with optical frequency combs in the extreme/visible ultraviolet spectral region requires a high peak power of the near-IR driving laser,and therefore high average power,pulse duration of a few tens of fs,and maximal available spectral bandwidth.Contrarily,the parametric conversion efficiency is higher for pulses with a duration in the 100-fs range due to temporal walk-off and coating limitations.Here we suggest an approach to adjust the spectral characteristics of high-power chirped-pulse amplification(CPA)to the requirements of different nonlinear frequency converters while preserving the low-phase-noise(PN)properties of the system.To achieve spectral tunability,we installed a mechanical spectral shaper in a free-space section of the stretcher of an in-house-developed ytterbium-fiber-based CPA system.The CPA system delivers 100 W of average power at a repetition rate of 132.4 MHz.While gaining control over the spectral properties,we preserve the relative-intensity-noise and PN properties of the system.The high-power CPA can easily be adjusted to deliver either a spectrum ideal for mid-IR light generation(full width at half maximum of∼11 nm,compressed pulse duration of 230 fs)or a spectrum ideal for highly nonlinear processes such as high-harmonic generation(−10 dB level of>50 nm,transform-limited pulse duration of∼65 fs).展开更多
As ultrafast laser technology advances towards ever higher peak and average powers,generating sub-50 fs pulses from laser architectures that exhibit best power-scaling capabilities remains a major challenge.Here,we pr...As ultrafast laser technology advances towards ever higher peak and average powers,generating sub-50 fs pulses from laser architectures that exhibit best power-scaling capabilities remains a major challenge.Here,we present a very compact and highly robust method to compress 1.24 ps pulses to 39fs by means of only a single spectral broadening stage which neither requires vacuum parts nor custom-made optics.Our approach is based on the hybridization of the multiplate continuum and.the multipass cell spectral broadening techniques.Their combination leads to significantly higher spectral broadening factors in bulk material than what has been reported from either method alone.Moreover,our approach efficiently suppresses adverse features of single-pass bulk spectral broadening.We use a burst-mode Yb:YAG laser emitting pulses with 80 MW peak power that are enhanced to more than 1 GW after postcompression.With only 0.19%rms pulse-to-pulse energy fluctuations,the technique exhibits excellent stability.Furthermore,we have measured state-of-the-art spectral-spatial homogeneity and good beam quality of M^(2)=1.2 up to a spectral broadening factor of 30.Due to the method's simplicity,compactness,and scalability,it is highly attractive for turning a picosecond laser into an ultrafast light source that generates pulses of only a few tens of femtoseconds duration.展开更多
文摘Tailoring the properties of the driving laser to the need of applications often requires compromises among laser stability,high peak and average power levels,pulse duration,and spectral bandwidth.For instance,spectroscopy with optical frequency combs in the extreme/visible ultraviolet spectral region requires a high peak power of the near-IR driving laser,and therefore high average power,pulse duration of a few tens of fs,and maximal available spectral bandwidth.Contrarily,the parametric conversion efficiency is higher for pulses with a duration in the 100-fs range due to temporal walk-off and coating limitations.Here we suggest an approach to adjust the spectral characteristics of high-power chirped-pulse amplification(CPA)to the requirements of different nonlinear frequency converters while preserving the low-phase-noise(PN)properties of the system.To achieve spectral tunability,we installed a mechanical spectral shaper in a free-space section of the stretcher of an in-house-developed ytterbium-fiber-based CPA system.The CPA system delivers 100 W of average power at a repetition rate of 132.4 MHz.While gaining control over the spectral properties,we preserve the relative-intensity-noise and PN properties of the system.The high-power CPA can easily be adjusted to deliver either a spectrum ideal for mid-IR light generation(full width at half maximum of∼11 nm,compressed pulse duration of 230 fs)or a spectrum ideal for highly nonlinear processes such as high-harmonic generation(−10 dB level of>50 nm,transform-limited pulse duration of∼65 fs).
文摘As ultrafast laser technology advances towards ever higher peak and average powers,generating sub-50 fs pulses from laser architectures that exhibit best power-scaling capabilities remains a major challenge.Here,we present a very compact and highly robust method to compress 1.24 ps pulses to 39fs by means of only a single spectral broadening stage which neither requires vacuum parts nor custom-made optics.Our approach is based on the hybridization of the multiplate continuum and.the multipass cell spectral broadening techniques.Their combination leads to significantly higher spectral broadening factors in bulk material than what has been reported from either method alone.Moreover,our approach efficiently suppresses adverse features of single-pass bulk spectral broadening.We use a burst-mode Yb:YAG laser emitting pulses with 80 MW peak power that are enhanced to more than 1 GW after postcompression.With only 0.19%rms pulse-to-pulse energy fluctuations,the technique exhibits excellent stability.Furthermore,we have measured state-of-the-art spectral-spatial homogeneity and good beam quality of M^(2)=1.2 up to a spectral broadening factor of 30.Due to the method's simplicity,compactness,and scalability,it is highly attractive for turning a picosecond laser into an ultrafast light source that generates pulses of only a few tens of femtoseconds duration.
