Low-Energy Laser Pulse Generates Relativistic Electron Beams

photonics | Posted: 24 Aug 2017, 10:11

Relativistic electrons driven by low-energy, ultrashort mid-infrared (MIR) laser pulses have been demonstrated for the first time, according to researchers. Many applications could use a lower energy and higher repetition rate accelerated beam, such as rapid-scan imaging for medical, scientific and security purposes. 
 
“We’re trying to develop laser-driven accelerators that are extremely compact and have a high repetition rate,” said professor Howard Milchberg, a professor of physics and electrical engineering at the University of Maryland. “That means using as low a laser pulse energy as possible to generate relativistic electrons.” 
 
Compared to prior experiments, the long-driver-wavelength low-energy femtosecond laser pulses used in this project resulted in easy access to what is called the “critical density” regime. Because the critical density varies inversely as the square of the laser wavelength, gas targets used for MIR laser pulses can be up to 100 times less dense than those used in the visible and NIR, making them far less difficult to engineer. 
 
“When a few-millijoule femtosecond mid-IR laser pulses are focused by a curved mirror into a hydrogen gas jet — a stream of hydrogen puffing out of a nozzle — a collimated pulse of relativistic electrons beams out the other side of the jet,” said Milchberg. “However, this can't happen unless the laser achieves an extremely high intensity — much higher than achievable by focusing with the curved mirror alone. It does so by relativistic self-focusing in the ionized hydrogen gas so that it collapses to a size much smaller than its focal spot.” 
 
The value of being in the critical density regime, according to Milchberg, is that it promotes relativistic self-focusing even for low energy laser pulses. This boosted high-intensity interaction generates plasma waves that accelerate some of the electrons from the ionized hydrogen into a forward-directed relativistic beam. 
 
Experiments demonstrated that electron beams were present for powers such that the characteristic self-focusing length in the plasma was shorter than the gas jet width, showing that electron acceleration cannot occur without relativistic self-focusing. 
 
Relativistic self-focusing is an extreme example of the process of self-focusing in nonlinear optics, but with 
the added bonus of accelerated relativistic particles generated from the nonlinear medium. Even with only 
20 mJ of MIR laser energy, the laser in these experiments could significantly exceed the threshold for relativistic self-focusing, giving rise to relativistic multifilamentation. The team observed multiple relativistic electron beamlets associated with these filaments. 
 
The team's findings represent early steps toward the development and application of high repetition rate laser driven accelerators. 
 
“In particular, long wavelength femtosecond lasers are especially promising, as they can access the relativistic nonlinear regime of free electrons surprisingly easily,” said Milchberg. 
 
The presentation entitled Laser wakefield acceleration with mid-IR laser pulses will take place at Frontiers in Optics + Laser Science APS/DLS (FIO + LS), an Optical Society event to be held September 17-21, 2017 at the Washington Hilton in Washington, DC.

Laser

NASA's ICESat-2 preps for laser tests

NASA's ICESat-2 preps for laser tests

Lasers that will fly on NASA's Ice, Cloud and land Elevation Satellite-2, or ICESat-2, are about to be put to the test at the agency's Goddard Space Flight Center in Greenbelt, Maryland.

Newly upgraded laser peers further into the extreme universe at SLAC's LCLS

Newly upgraded laser peers further into the extreme universe at SLAC's LCLS

Scientists at the Department of Energy's SLAC National Accelerator Laboratory recently upgraded a powerful optical laser system used to create shockwaves that generate high-pressure conditions like those found within planetary interiors.

Breakthrough ink discovery could transform the production of new laser and optoelectronic devices

Breakthrough ink discovery could transform the production of new laser and optoelectronic devices

A breakthrough 'recipe' for inkjet printing, which could enable high-volume manufacturing of next-generation laser and optoelectronic technologies, has been uncovered by Cambridge researchers.

Anapole Lasers Generate Ultrafast Pulses for Managing Nanoscale Optics

Anapole Lasers Generate Ultrafast Pulses for Managing Nanoscale Optics

Anapole lasers made from semiconductors shaped into energy-storing nanodisks could be useful as an energy source for nanoscale optics in silicon-compatible platforms.

Sparkle Optics successfully delivers illuminator laser to AFRL

Sparkle Optics successfully delivers illuminator laser to AFRL

Sparkle Optics received a Phase III Small Business Innovation Research (SBIR) award from the High Energy Laboratory Joint Technology Office (HEL-JTO) in 2012 to develop, optimize, and test illuminator lasers based on Sparkle Optics Rotary Disk Laser (RDL) technology.

New research initiative turns laser focus on high-energy-density physics

New research initiative turns laser focus on high-energy-density physics

New research initiative turns laser focus on high-energy-density physics.

IPG Photonics Q2 2017 revenue increases 46%--another record

IPG Photonics Q2 2017 revenue increases 46%--another record

For its second quarter ended June 30, 2017, IPG Photonics (Oxford, MA) reported revenue and earnings per diluted share at record levels, increasing 46% and 53%, respectively.

TRUMPF's sales increase by almost 11% in 2016/2017

TRUMPF's sales increase by almost 11% in 2016/2017

TRUMPF generated a significant 10.8% increase in sales in the 2016/2017 fiscal year ending June 30, 2017.

Riddell Joins NKT Photonics as COO

Riddell Joins NKT Photonics as COO

Fiber provider NKT Photonics AS has appointed Don Riddell as COO, taking responsibility for the company’s three manufacturing sites.

BLM Group USA opens new headquarters and tech center

BLM Group USA opens new headquarters and tech center

Laser tube cutting equipment supplier BLM Group USA (Novi, MI) has opened its new 75,000-sq-ft. headquarters.

TRUMPF demonstrates 4kW high-brilliance direct-diode laser

TRUMPF demonstrates 4kW high-brilliance direct-diode laser

Laser and laser system manufacturer TRUMPF unveiled its TruDiode 4001.5 technology demonstrator at the LASER World of PHOTONICS 2017 trade fair.

Laser cutting provider Prescient relocates headquarters to North Carolina

Laser cutting provider Prescient relocates headquarters to North Carolina

Prescient, whose manufacturing solutions include laser cutting for the construction industry, is moving the company's headquarters from Arvada, CO, to Durham, NC, as well as opening a second manufacturing facility in nearby Mebane, NC.

Integrated-photonics laser has record-narrow chip-based linewidth of 290 Hz

Integrated-photonics laser has record-narrow chip-based linewidth of 290 Hz

Researchers from the University of Twente's MESA+ Institute for Nanotechnology and chipmaking company LioniX International have developed the world's most-narrowband laser diode on a chip.

Strengthening material processing business, NKT Photonics to acquire Onefive

Strengthening material processing business, NKT Photonics to acquire Onefive

NKT Photonics, which supplies fiber lasers and photonic-crystal fibers, has entered into an agreement to acquire ultrafast laser maker Onefive.

VI Systems offers 56-Gbps NRZ laser driver and transimpedance amplifier for CEI-56G applications

VI Systems offers 56-Gbps NRZ laser driver and transimpedance amplifier for CEI-56G applications

VI Systems GmbH says its sampling a vertical cavity surface emitting laser (VCSEL) driver and limiting transimpedance amplifier (TIA) for 56-Gbps non-return-to-zero (NRZ) modulation.

Nonlinear optical crystal changes the color of laser light on the femtosecond time scale

Nonlinear optical crystal changes the color of laser light on the femtosecond time scale

Nonlinear optical crystal changes the color of laser light on the femtosecond time scale.

Diamond lenses make materials-processing laser optics lighter

Diamond lenses make materials-processing laser optics lighter

Diamond lenses make materials-processing laser optics lighter.

IPG Photonics to acquire Innovative Laser Technologies

IPG Photonics to acquire Innovative Laser Technologies

Laser systems maker IPG Photonics has signed an agreement to acquire Innovative Laser Technologies (ILT) for $40 million in cash.

Clemson Receives Funding from DoD for Laser Weaponry Research

Clemson Receives Funding from DoD for Laser Weaponry Research

Two researchers at Clemson University are taking different but complementary approaches to creating a high-energy laser that could be used as a weapon. The engineers are receiving a combined $3.2 million from the U.S. Department of Defense (DoD) to help fund the research.

Power-scalable semiconductor laser is focus of UTA research grant

Power-scalable semiconductor laser is focus of UTA research grant

Conventional high-power lasers are bulky and require equipment that makes them difficult to use in portable platforms, but a University of Texas at Arlington engineer is working to develop a semiconductor laser that addresses these issues.

IPG Photonics acquires volume Bragg gratings maker OptiGrate

IPG Photonics acquires volume Bragg gratings maker OptiGrate

IPG Photonics has acquired OptiGrate, whose volume Bragg grating (VBG)-based components improve performance, miniaturization, and cost reduction of ultrafast lasers for micromachining, medical, and other applications.

Graphene may serve as fast saturable absorber

Graphene may serve as fast saturable absorber

Graphene may serve as fast saturable absorber.

XFEL Generates First Laser Light

XFEL Generates First Laser Light

The European X-ray Free-Electron Laser (XFEL), the largest x-ray laser in the world, has generated its first laser light, reaching the last major milestone before its official opening in September.

Focuslight completes acquisition of micro-optics maker LIMO

Focuslight completes acquisition of micro-optics maker LIMO

High-power laser diode maker Focuslight Technologies has completed its acquisition of LIMO Lissotschenko Mikrooptik (Dortmund, Germany), a supplier of micro-optics and beam shaping systems. The transaction was funded by issuing shares of stock to investors.

University of Strathclyde acquires 350 TW laser from Thales

University of Strathclyde acquires 350 TW laser from Thales

One of the world's most powerful lasers--capable of bursts of light equivalent to twenty times all the power consumed on Earth, captured in fraction of a second--has been acquired by the University of Strathclyde.

LaserBond ships first laser cladding system to China

LaserBond ships first laser cladding system to China

LaserBond has shipped its first customized laser cladding system to China in a AU$1.4 million (US$1.03 million) deal.

Researchers develop automated laser process for cutting sheet piling underwater

Researchers develop automated laser process for cutting sheet piling underwater

Researchers at Laser Zentrum Hannover (LZH), in collaboration with the Institute of Materials Science at the Leibniz University of Hannover (both in Hannover, Germany), is developing a laser-based, automated process for cutting sheet piling underwater.

MicroVision Signs Laser Beam Scanning System Contract

MicroVision Signs Laser Beam Scanning System Contract

Display and sensor developer MicroVision Inc. has signed a contract with a major technology company to develop a laser beam scanning (LBS) display system and produce specific components.

LightFab to introduce selective laser etching to US market

LightFab to introduce selective laser etching to US market

PhotoMachining and LightFab have begun a collaborative effort to promote selective laser etching (SLE) using femtosecond lasers in the US market.

Research team develops visible light-activatable drug to treat pain

Research team develops visible light-activatable drug to treat pain

A team of researchers at the Institute of Neurosciences of the University of Barcelona (Spain) and colleagues has developed a light-activated drug for pain treatment.

Fixed Focal Length Lenses

Fixed Focal Length Lenses

The TECHSPEC Compact Ruggedized (Cr) series of fixed focal length lenses from Edmund Optics Inc. includes stability...

Sapphire and Ruby Balls

Sapphire and Ruby Balls

A line of sapphire and ruby balls from Meller Optics is designed for use as ball check valves, stylus tips, fiber optic lens...

UV Lamp

UV Lamp

The Model 629 hollow cathode UV lamp from McPherson Inc. is a flow-controlled, windowless broad-spectrum source that emits...

UV and Green Lasers

UV and Green Lasers

Coherent Inc. has added the 355-55 UV and 532-80 green models to its AVIA line of industrial lasers.