Progress of industrial femtosecond machining
A rich 20-year history  

Micromachining with femtosecond lasers (also known as ultrafast or ultra-short pulse lasers) is gaining popularity due to several advantageous properties, including the nearly athermal, or "cold," ablation process. For industries demanding smaller and more precise parts, this technology offers several benefits, including higher yields, tighter tolerances, little to no collateral damage, and no post processing.

While femtosecond lasers have begun gaining significant attention in recent years, they were originally showcased 20 years ago at the Laser World of Photonics in Munich, Germany by Clark-MXR, a company founded in 1992 in Dexter, MI. With the help of few other collaborators, Clark-MXR presented the first live demonstration of industrial femtosecond laser micromachining during an exposition or conference.

The image above depicts a glass slide machined with femtosecond laser pulses from a CPA-Series laser from Clark-MXR. These proof-of-principal parts were machined in real time during the show in Munich and given to attendees for them to take home.

Since this pioneering feat at the 1997 Laser World of Photonics, Clark-MXR has remained a key player in femtosecond laser micromachining, continuing to develop innovative processes and equipment, as well as providing femtosecond laser-based micromachining services to numerous industries.

Please join Clark-MXR at Laser World of Photonics in Munich, booth B2-207, to celebrate the success and the 20th anniversary of commercial femtosecond laser-based micromachining.

Catching molecules in the act 

Chemical reactions are characterized by the motion of atoms; transformation of chemical compounds, reactants, and raw materials is therefore governed by molecular vibrations. While the motion of the atoms is easily seen at the beginning and end of a chemical reaction, the molecular changes occur too rapidly in the middle of the process, making them impossible for humans to observe.

With novel techniques that employ the use of ultrafast lasers, however, we can essentially freeze the chemical reaction. This allows us to thoroughly observe the intermediate steps of the chemical reaction that were previously incomprehensible, even permitting control of these reactions. Surface Enhanced Femtosecond stimulated Raman Spectroscopy (SE-FSRS) is one such technique: with SE-FSRS, we are able to study chemical bond-breaking and formation at the femtosecond timescale. (Some perspective: one femtosecond is one millionth of one billionth of a second.)

The research group of Professor Richard Van Duyne at Northwestern University utilized and improved upon the SE-FSRS technique in this study of chemical reaction dynamics. In this research, the experiments were performed at 1 MHz repetition rate using the IMPULSE laser from Clark-MXR, Inc., the first time that the SE-FSRS technique has been used with a laser source running at this repetition rate. The researchers found that the 1 MHz system resulted in several advantages when compared to previous implementations that used lower repetition rate lasers: the 1 MHz system allowed for a lower pulse energy and a minimized sample exposure time, leading to less sample degradation and increased signal to noise. The success of this research has established SE-FSRS as a robust tool for studying molecular dynamics, opening the door to several other potential applications of the technology. 

In their next endeavor, the researchers at Northwestern University are planning to perform time-dependent studies, which will allow them to effectively catch the molecules in their act. 

More information: The original article: Surface-Enhanced Femtosecond Stimulated Raman Spectroscopy at 1 MHz Repetition Rates. Lauren E. Buchanan, Natalie L. Gruenke, Michael O. McAnally, Bogdan Negru, Hannah E. Mayhew, Vartkess A. Apkarian, George C. Schatz and Richard P. Van Duyne.  Appers in J. Phys. Chem. Lett. 2016, 7, 4629−4634 (DOI: 10.1021/acs.jpclett.6b02175)

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Synchronization of a 25 MHz Magellan Yb-doped Fiber Oscillator with a Streak Camera from Optronis       Clark-MXR, Inc. is pleased to announce the first demonstration of a Yb-doped femtosecond fiber oscillator running at 25 MHz successfully synchronized with a Streak camera. This is a result from a collaboration with the companies Optronis GmbH (Dr. Patrick Summ, summ@optronis.com) and Horiba Scientific GmbH (Dr. Hans-Erik Swoboda hans-erik.swoboda@horiba.com) from Europe. The Magellan is a telecom-qualified single emitter diode-pumped Yb-doped femtosecond fiber oscillator. A Streak camera from Optronis, Optoscope SC10, with Synchroscan sweep unit was triggered by the Magellan oscillator and different triggering set-ups were tested for best synchronization conditions and temporal resolutions.   This will open up a whole new research area that was unavailable until now to synchronize Yb-doped fiber oscillators with streak cameras at lower repetition rates. Experiments such as direct fluorescence lifetime measurements with high temporal resolution can now be implemented.

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Clark-MXR is Laser Institute of America's Featured Member in July

 

An industry leader in Ultrashort Pulse laser based micromachining and the production of ultrafast lasers and laser-based solutions for scientific research and industrial applications, Clark-MXR, Inc. is known for offering unparalleled contract manufacturing services and easy-to-use laser products at a low cost of ownership.

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Recent publication from KAUST with Model IMPULSE:

Mapping Carrier Dynamics on Material Surfaces in Space and Time using Scanning Ultrafast Electron Microscopy

Jingya Sun, Aniruddha Adhikari, Basamat S. Shaheen, Haoze Yang, and Omar F. Mohammed*
Solar and Photovoltaics Engineering Research Center, Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia

DOI: 10.1021/acs.jpclett.5b02908

ABSTRACT: 

Selectively capturing the ultrafast dynamics of charge carriers on materials surfaces and at interfaces is crucial to the design of solar cells and optoelectronic devices. Despite extensive research efforts over the past few decades, information and understanding about surface-dynamical processes, including carrier trapping and recombination remains extremely limited. A key challenge is to selectively map such dynamic processes, a capability that is hitherto impractical by time-resolved laser techniques, which are limited by the laser’s relatively large penetration depth and consequently these techniques record mainly bulk information. Such surface dynamics can only be mapped in real space and time by applying four-dimensional (4D) scanning ultrafast electron microscopy (S-UEM), which records snapshots of materials surfaces with nanometer spatial and subpicosecond temporal resolutions. In this method, the secondary electron (SE) signal emitted from the sample’s surface is extremely sensitive to the surface dynamics and is detected in real time. In several unique applications, we spatially and temporally visualize the SE energy gain and loss, the charge carrier dynamics on the surface of InGaN nanowires and CdSe single crystal and its powder film. We also discuss the mechanisms for the observed dynamics, which will be the foundation for future potential applications of S-UEM to a wide range of studies on material surfaces and device interfaces.

Recent publication with Model IMPULSE from Clark-MXR

Time-resolved photoemission study of the electronic structure and dynamics of chemisorbed alkali atoms on Ru(0001)

Shengmin Zhang, Cong Wang, Xuefeng Cui, Yanan Wang, Adam Argondizzo, Jin Zhao, and Hrvoje Petek
Department of Physics and Astronomy and Pittsburgh Quantum Institute, University of Pittsburgh, & Department of Physics and ICQD/Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei,  China.

DOI: 10.1103/PhysRevB.93.045401

Abstract

We investigate the electronic structure and photoexcitation dynamics of alkali atoms (Rb and Cs) chemisorbed on transition-metal Ru(0001) single-crystal surface by angle- and time-resolved multiphoton photoemission. Three- and four-photon photoemission (3PP and 4PP) spectroscopic features due to the σ and π resonances arising from the ns and np states of free alkali atoms are observed from ∼2 eV below the vacuum level in the zero-coverage limit. As the alkali coverage is increased to a maximum of 0.02 monolayers, the resonances are stabilized by formation of a surface dipole layer, but in contrast to alkali chemisorption on noble metals, both resonances form dispersive bands with nearly free-electron mass. Density functional theory calculations attribute the band formation to substrate-mediated interaction involving hybridization with the unoccupied d bands of the substrate. Time-resolved measurements quantify the phase and population relaxation times in the three-photon photoemission (3PP) process via the σ and π resonances. Differences between alkali-atom chemisorption on noble and transition metals are discussed.