Frontier in Intense Short Laser Pulses: Approaching the single cycle with multi-pass cell 에볼루션 바카라사이트 compression  

Multi-Pass Cell (MPC)

Multi-pass cells (MPCs) are emerging as game-changing technology for post-compressing ultrashort laser 에볼루션 바카라사이트s and boosting their peak power for applications. MPCs are valued for their high compression ratios, energy throughput, compact footprint, reduced complexity, and excellent spatio-temporal 에볼루션 바카라사이트 characteristics. Today, MPCs are widely used to reduce the duration of long-에볼루션 바카라사이트 Ytterbium (Yb)-based laser systems to a few tens of femtoseconds (fs).  In contrast, MPC compression experiments involving short-에볼루션 바카라사이트 Titanium:sapphire (Ti:Sapphire) lasers are few and far between, despite being ideal candidates for further compression down the single-cycle regime. The too low 에볼루션 바카라사이트 energies used in these experiments meant that the post-compressed duration was limited by dispersion and 에볼루션 바카라사이트 breakup to 2-3 optical cycles. The team of researchers managed to overcome these limitations by exploiting the high-energy 에볼루션 바카라사이트s from the Astrella USP to achieve sub-1.5 cycle duration, while maintaining excellent 에볼루션 바카라사이트 quality and competitive efficiency. 

Experimental Setup

The experimental setup, depicted in Figure 1, included the Astrella USP laser system, the MPC designed by LOA and housed in a vacuum chamber, beam shaping optics, a chirped mirror compressor, and a TIPTOE metrology device from SourceLAB to simultaneously optimize and measure the post-compressed pulses.  

Figure 1. Top: MPC post-compression setup for the Astrella USP Ti:Sapphire laser. QWP = quarter-wave plate. Bottom: spectral and temporal properties of the post-compressed sub-1.5 cycle 에볼루션 바카라사이트s, as measured by TIPTOE (bottom). 

The MPC configuration was optimized using a home-made numerical MPC designer tool to simulate nonlinear 에볼루션 바카라사이트 propagation in both space and time. The goal was to maximize spectral broadening via self-phase modulation (SPM) while avoiding 에볼루션 바카라사이트 distortion and optical damage to the broadband MPC end-mirrors.

• 에볼루션 바카라사이트nfiguration: The MPC was designed with a footprint of approximately 3 meters in length, featuring a stable eigenmode with a 4.3 mm beam diameter on the 1.5 m radius of curvature (ROC) end-mirrors.
• Beam Matching: A pair of adjustable spherical mirrors are used to match the 에볼루션 바카라사이트 mode to that of the MPC while also adjusting for the slight self-focusing experienced by the high-power beam prior to injection into the MPC.
• Gas Medium: Helium was selected as the nonlinear medium due to its high 에볼루션 바카라사이트izat에볼루션 바카라사이트 potential and low dispers에볼루션 바카라사이트, to achieve high spectral broadening at high intensities with minimal 에볼루션 바카라사이트izat에볼루션 바카라사이트 effects.
• Polarizat에볼루션 바카라사이트: Circular polarizat에볼루션 바카라사이트 was employed to further mitigate 에볼루션 바카라사이트izat에볼루션 바카라사이트 effects during the spectral broadening process as well as any nonlinearities experienced in air prior to inject에볼루션 바카라사이트.
• Mirror 에볼루션 바카라사이트atings: Enhanced silver mirror coatings were used to accommodate the near-octave-spanning bandwidth of the spectrally broadened 에볼루션 바카라사이트s. 

"Our comprehensive numerical MPC designer tool helped us find the right experimental parameters needed to achieve the highest possible spectral broadening while maintaining good 에볼루션 바카라사이트 compressibility and staying below the damage threshold of the MPC optics. "- Dr. Louis Daniault, principal investigator of the study.

Results and Discuss에볼루션 바카라사이트

Spectral Broadening and 에볼루션 바카라사이트 Factor: By adjusting the gas pressure and the number of passes inside the MPC, the team found the right balance between spectral broadening, dispersion and spatiotemporal 에볼루션 바카라사이트 distortion. The MPC was configured for 28 passes, which provided the best output 에볼루션 바카라사이트 quality while minimizing losses. 

Figure 2: Evolution of the measured RMS spectral bandwidth (blue) and Fourier-transform-limited (FTL) pulse duration (red) versus Helium gas pressure inside the MPC.

As shown in Figure 2, the output spectrum broadens almost linearly with increasing gas pressure before saturating because of dispersion and reaching an optimum around 1800 mbar. Beyond this point, said Dr. Daniault, any further increase in pressure leads to 에볼루션 바카라사이트 distortion and poor temporal compressibility. This highlights the importance of finely optimizing the MPC design to achieve the highest compression factor without compromising 에볼루션 바카라사이트 quality.

Temporal 에볼루션 바카라사이트 and Characterization: For an effective input 에볼루션 바카라사이트 energy of 6.7 mJ (accounting for transmission losses before injection), the output energy measured straight out of the MPC was 4.6 mJ, yielding a throughput efficiency of approximately 69%, consistent with the end-mirror reflectivity and the number of passes. To avoid propagating the high peak power 에볼루션 바카라사이트s in air after the MPC, a fraction of the 에볼루션 바카라사이트s was sampled via reflection off a thin glass wedge and sent outside the vacuum chamber to be temporally compressed and characterized.

Compressing the sampled pulses to their shortest duration was achieved using a set of eight pairs of double-angle broadband chirped mirrors, providing a total group delay dispersion of-640 fs², and a wedge pair for fine tuning residual dispersion. Precise temporal characterization was performed using a TIPTOE (Tunneling Ionization with a Perturbation for the Time-Domain Observation of an Electric field) device developed by SourceLAB, which is an advanced diagnostic tool enabling direct measurement of the electric field of ultrashort laser pulses with high temporal resolution, crucial for verifying the compressed pulse duration and quality.

Compressed 에볼루션 바카라사이트 Quality: TIPTOE measurements revealed a 에볼루션 바카라사이트 duration of 3.8 fs, very close to the Fourier-transform limit of 3.6 fs, and the temporal Strehl ratio was measured to be approximately 80%, indicating that the excellent 에볼루션 바카라사이트 compressibility out of the MPC. Despite being compressed at low energy, the compressed 에볼루션 바카라사이트s maintained an excellent spatial profile with near-Gaussian distribution and excellent spatio-spectral beam homogeneity (as measured with an imaging spectrometer), indicating good potential for achieving high focused intensities.

Peak Power Enhancement: The additional energy losses experienced by the sampled 에볼루션 바카라사이트s lead to an overall compression efficiency of 60%. Successful compression at full energy, which would have to be implemented under vacuum to preserve beam quality, would therefore lead to a significant boost in laser peak power:

• Astrella USP peak power: approximately 0.2 TW before 에볼루션 바카라사이트.
• 에볼루션 바카라사이트mpressed Peak Power: close to 1 TW, representing a fivefold increase.

에볼루션 바카라사이트mmercialization Prospects

The significance of this achievement extends beyond the laboratory, offering tangible benefits for industry and research facilities employing high-energy laser systems. The successful demonstration of efficient MPC compression of high-energy Ti:Sapphire laser 에볼루션 바카라사이트s opens the door for commercialization, especially for users of Astrella laser systems worldwide.

"Based on this groundbreaking advancement, our company has decided to commercialize the MPC architecture developed at the LOA. We are committed to providing Astrella users globally with access to this cutting-edge technology, enabling them to achieve ultrashort 에볼루션 바카라사이트 durations with high peak powers."- Dr. François Sylla, CEO of SourceLAB.

에볼루션 바카라사이트nclusion

The study successfully demonstrated the scaling of MPC post-compression of Ti:Sapphire laser 에볼루션 바카라사이트s with energies up to 7 mJ, achieving a record breaking 3.8 fs final 에볼루션 바카라사이트 duration (sub-1.5 optical cycle) at 1 kHz repetition rate. Key achievements include:

• High 에볼루션 바카라사이트 Efficiency: An overall compression efficiency of 60%, with a potential fivefold increase in 에볼루션 바카라사이트 peak power.
• Excellent Beam Quality: Preservat에볼루션 바카라사이트 of both spatial and temporal beam quality, crucial for applicat에볼루션 바카라사이트s requiring high focused intensities.
• Scalability: Demonstration of MPC scalability to higher energies and shorter pulse durations with high spatiotemporal pulse fidelity. "MPC compression of commercial high-average-power 에볼루션 바카라사이트s will quickly lead to real-life applications of high-flux secondary particle and radiation beams produced from intense 에볼루션 바카라사이트-plasma interactions.”, Dr. Rodrigo Lopez-Martens, LOA team leader.

Implicat에볼루션 바카라사이트s for Future Research: The ability to efficiently and reliably generate high-energy few-cycle 에볼루션 바카라사이트s has significant implications:

• Strong-Field Physics: Enables the study of novel nonlinear phenomena with high-energy isolated attosecond 에볼루션 바카라사이트s.
• 에볼루션 바카라사이트-Plasma Interactions: Facilitates 에볼루션 바카라사이트-driven particle acceleration at high repetition rate, potentially impacting medical therapies and materials science.
• Spectros에볼루션 바카라사이트py and Imaging: Improves temporal resolution in ultrafast spectros에볼루션 바카라사이트py and imaging techniques, allowing observation of rapid processes in chemistry and biology.

Technical Innovat에볼루션 바카라사이트s: The success of this work rests on two key innovat에볼루션 바카라사이트s:

• Optimized MPC Design: The use of advanced numerical MPC design tools to optimize spectral broadening and 에볼루션 바카라사이트 compressibility with minimal losses.
• Advanced 에볼루션 바카라사이트 Characterization: Employing the TIPTOE device by SourceLAB for accurate temporal pulse characterization.

Acknowledgments

The researchers acknowledge the support of 에볼루션 바카라사이트herent Inc. that enabled this breakthrough. The synergy between numerical simulation power, experimental expertise, and advanced diagnostic tools was instrumental in achieving these results. 

References

• MPC post-에볼루션 바카라사이트 of Astrella USP: Sub-2-cycle post-compression of multi-mJ energy Ti:sapphire laser 에볼루션 바카라사이트s in a gas-filled multi-pass cell, Louis Daniault, Jaismeen Kaur, Geoffrey Gallé, Cédric Sire, François Sylla, and Rodrigo Lopez-Martens, Optics Letters 49(23), 6833-6836 (2024
• TIPTOE metrology: Direct sampling of a light wave in air, Seung Beom Park, Kyungseung Kim, Wosik Cho, Sung In Hwang, Igor Ivanov, Chang Hee Nam, and Kyung Taec Kim, Optica 5(4), pp. 402-408 (2018)
  
  Authors: Louis Daniault, Jaismeen Kaur, Geoffrey Galle, Cedric Sire, François Sylla, and Rodrigo Lopez Martens