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Advanced Beam Laboratory

Advanced Laser for Extreme Photonics (ALEPH)

  • Colorado State University
  • Petawatt-Class Laser
  • Laser Type: ultra-short pulse Ti:sapphire laser system

Colorado is the #2 state for Technology & Science and the #4 state in concentration of STEM professionals—making it an ideal location for research across a wide range of industries. Based in the scenic foothills of Colorado State University, the ABL combines expertise in accelerator science and technology and advanced high-intensity solid state lasers.

Capabilities

Jorge Rocca

Jorge Rocca

Office: C101E Engineering Building

Phone: 970-491-8371

Email: jorge.rocca@colostate.edu

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Overview

Colorado State University Petawatt-Class Laser is an ultra-short pulse Ti:sapphire laser system that produces ultrahigh-contrast λ = 400 nm femtosecond pulses of up to 10 J, obtained by frequency doubling 800 nm pulses of 45 fs duration. An intensity of 6.5x1021 W/cm2 is obtained focusing the beam with an f/2 parabola. Up to a maximum of 26 J are available at the fundamental wavelength with degraded contrast. A new long focal length f/25 beamline was commissioned in August 2020 and is available to users. Both beamlines can be operated with high contrast = 400nm or with the fundamental. The beam/pulse parameters presently offered by the laser are summarized in the Laser Modes table.

Target Areas

The facility includes a target chamber 1.2m in diameter shown in Figure 2. There are NW 200 and NW 100 located on the equator. A motorized target holder system designed to hold numerous targets and an accurate target positioning system are available. A Solid Works™ generated parasolid model of the target chamber can be downloaded here.

A suite of plasma diagnostics instrumentation is available.
These include:

Plasma Diagnostics instrumentation

A suite of plasma diagnostics instrumentation is available. These include:

  • X-ray detection
    • Von Hamos crystal spectrometer operating with a 4cm radius of curvature mica crystal covering the 7 keV to 13 keV spectral region
    • Filtered silicon photodiode array; filters are available with cut-off between 1 keV and 15 keV
    • Step wedge spectrometer
  • Ion detection
    • Thomson parabola spectrometer with MCP/CCD detector
  • Neutron detection
    • Array of four scintillator/photomultiplier neutron detectors
    • Bubble detectors

 

A schematic diagram of the laser is shown in Figure 1. It consists of a conventional Ti:Sa front end that delivers λ=800 nm pulses into a chain of three high power Ti:Sa amplification stages pumped by Nd:YAG slab amplifiers. The 250 mJ output of this laser front end is further amplified in three multi-pass Ti:Sa amplifiers pumped by the frequency doubled output of eight compact flash lamp-pumped high energy Nd:glass slab amplifiers, developed at CSU. The slab geometry has long been recognized as a way to significantly reduce the limitations in repetition rate inherent to the more commonly used rod geometry. These pump laser allows Ti:sapphire system operation at a repetition rate of up to 3.3 Hz in burst mode. The beam propagates in a zig-zag path in the gain medium aided by total internal reflection in the polished wall of the slabs eliminating first-order thermal and stress-induced focusing, and also reducing stress-induced birefringence.

Figure 1: Schematic Diagram of 3.3 Hz, 0.85 PW CPA Ti:Sa Laser System. Top: Ti:Sa  laser, frequency doubling set up and target chamber. Bottom:  Pump laser based on Nd:glass slab amplifiers designed to operate at 5 Hz repetition rate. VT: Vacuum Tube; SA: Serrated Aperture; SF: Spatial Filter; AT: Anamorphic Telescope; WP: Wave Plate. 

 

 

 

Each slab amplifier generates pulses with ~18 J energy and 15 ns duration at 1053 nm. The rms pulse energy fluctuation for 1053nm slab pump laser is ~1%. The amplified beams are frequency doubled by LBO crystals to generate 11 J pulses at 527 nm. The eight slab amplifier arms produce a total 527 nm pump energy of 88 J, with a uniform nearly flat-top beam profile this is used to pump the three main Ti:Sa amplifiers. The amplifier chain generates 800 nm pulses of up to 37 J energy before compression. A gold grating compressor compresses these pulses into pulses of up to 26 J energy with duration as shot as 30 fs. These pulses are frequency doubled to generate the ultrahigh contrast 400 nm pulses that constitute the normal mode of operation.

Figure 2: Image of the 1.2 m diameter target chamber

ALEPH 400 nm

Parameter Value Unit Additional Information
Center Wavelength 400 nm  
Pulse duration (I FWHM) 45 fs  
Max energy on target 10 J  
Shot energy stability 10 % r.m.s.
Focal spot at target      
F/number f/2    
intensity FWHM 1.2 μm  
Strehl ratio      
Energy containment 65 % within 1/e   radius
F/number f/25          
focal spot FWHM 20 μm        
Strehl ratio            
Energy containment 70 % within 1/e   radius
Pointing Stability 2 μrad  
Pre-pulse contrast      
ps scale 10-12   @ >25 ps
Repetition Rate 3.3    

ALEPH 800 nm

Parameter Value Unit Additional Information
Center Wavelength 800 nm  
Pulse duration (I FWHM) 30 fs  
Max energy on target 26 J  
Shot energy stability 1.7 % r.m.s.      
Focal spot at target      
F/number f/2    
intensity FWHM 2.4 µm  
Strehl ratio      
Energy containment 65 % within   µm radius
F/number f/25          
focal spot FWHM 40 µm        
Strehl ratio            
Energy containment 70 % within   1/e radius
Pointing Stability 2 µrad  
Pre-pulse contrast      
ps scale 5x10-6   @ > 25 ps
Repetition Rate 3.3 Hz   burst mode

Contacts

Have a question or need assistance with your research?

Please address
inquiries to:

Email: advancedbeamlab@colostate.edu

News, Events & Publications

Oct 27, 2020    News

LaserNetUS High-Power Laser Consortium, Including Berkeley Lab, Receives $18M From the U.S. DOE

WASHINGTON, D.C. – Today, the U.S. Department of Energy (DOE) announced $18 million to fund operations and user...

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Jan 16, 2020    News

HEDLP Funding Opportunity Announcement DE-FOA-0002233

Letter of Intent due Jan 30, 2020. Proposals due March 16, 2020.

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