|
Lasers
-
Products
| Gratings: This
web page has a complete listing of high performance
gratings we make along links to graphs of S & P diffraction efficiencies, dispersion, Bragg Angle
sensitivity, and PDL where applicable
|
| |
|
| |
|
|
Optics Letters / Volume 30, No 5 / March 1, 2005
"Multimillijoule chirped parametric amplification of few-cycle pulses": Andrius Baltuska et al
|
|
|
|
Laser
Pulse Compression & Stretching
Description
Highly effective compression and stretching of
picosecond and femtosecond laser pulses can be accomplished by using matched
pairs of Volume Phase Holographic Gratings (VPHGs) in transmission geometry. As shown in the figure below, compression
and stretching is proportional to the distance between the parallel gratings. A mirror can be inserted to double the
dispersion and/or two identical lenses can be placed two focal lengths
apart for compression purposes.
Benefits
Diffraction efficiencies >90%, combined with angles up to 70 degrees for S (TE) polarization, produce high throughput, compact devices.
Example Graph Below of 1213 lpmm grating (70.1 degrees) for 1550nm
Energy Density Information
We are collecting energy density data from various pulsed laser companies. Energy density failure is a mostly a function of the glue/gelatin/glass assembly with the glue usually failing first by softening. Below is information typical of a successful medical pulsed laser application. Continuous wave (CW) energy densities of up to ~10 watts/cm^2 are fine; up to ~100 10 watts/cm^2 is possible with suitable epoxies..
|
Energy Density Measurements (approximate) from Customers
- 2 Piece Glass Construction: Grating Diagrams
- BK7 (2mm substrate + 2mm cover glass) and water white (1mm substrate + 1mm cover glass
- NOA 61 or NOA 63 Epoxy: thickness ~25-50 microns
- DCG Films: thicknesses vary from ~3-10 microns
|
Description |
Application #1 |
Application #2 |
Application #3 |
Pulsed Laser Type |
1054nm, S polarized |
800nm, P polarized |
530nm, P polarized |
Grating Size |
>25mm |
>10mm |
>10mm |
Beam Diameter |
5mm |
3mm |
1.5mm |
Pulse Duration |
500 fs |
130 fs |
<200 fs |
Energy/pulse |
30 microjoules |
360 microjoules |
7 microjoules |
Repetition Rate |
>10 KHz |
1 KHz |
1 KHz |
Average Power
(Energy/pulse X Repetition Rate ) |
>300 mW |
>300 mW |
>7 mW |
Average Power Density
(Average Power / Beam Area) |
>1.5 Watts/cm2 |
>5 Watts/cm2 |
0.5 Watts/cm2 |
Peak Power
((Energy/pulse) / Pulse Duration) |
6x10^7 Watts |
3x10^9 Watts |
>3x10^7 Watts |
Peak Power Density
(Peak Power / Beam Area) |
3x10^8 Watts/cm2 |
4x10^10 Watts/cm2 |
2x10^9 Watts/cm2 |
Test Duration |
In commercial use |
1.5 hours with no failure |
Preliminary |
|
External Cavity Laser Tuning
Description
External cavity diode and dye lasers can be spectrally tuned and made to
operate in a single-mode. Light exiting from the laser cavity
diverges, passes through a collimator, and is imaged on a grating. In
Littrow and Littman configurations, the grating is positioned so that light
of the correct wavelength is redirected back through the collimator and
focused into the laser cavity. Gratings for single or dual polarizations can be produced.
Littman System Using VPH Transmission Gratings, S (TE) Maximized
Grating Enhanced External Cavity Laser Diode (GEECLD): Graphs & diagrams courtesy of Andreas Wicht, University of Dusseldorf
|
|
|
Benefits
- Tunable Diffraction Efficiency (>90%): High diffraction efficiencies are helpful to detune the laser far away from gain maximum. Alternatively, to circumvent the gain maximum, especially at high currents, lower diffraction efficiencies are preferred.
- Higher Spatial Frequencies (=> More Compact): In all Littman diode setups, transmission gratings allow the application of line densities which are about twice as large as for reflection gratings. This is because the first order is diffracted back into the laser diode, and not at ~90 degrees with respect to the incident beam.
- Maximum Diffraction Efficiency: Higher efficiency than commercial reflection gratings.
- Continuous Tuning Over A Wide Band
|
|
Stock: Dual Polarization VPH Transmission Gratings: AOI=AOD |
Description |
Spatial Frequency |
Center Wavelength |
AOI/AOD at CWL |
S & P Efficiencies |
Dickson® Grating |
940 lpmm |
1550nm |
46.8o |
>90% |
Dickson® Grating |
1145 lpmm |
1310nm |
48.6o |
>90% |
|
Custom VPH Transmission Gratings: >90% Efficiencies
- Polarizations Maximized: Single or dual polarization gratings (including Dickson® Gratings)
- Symmetric or Non-Symmetric: Angle of Incidence (AOI) = Angle of Diffraction (AOD) or AOI ¹ AOD
- Frequencies: 400-4000 l/mm · Wavelength Ranges: 350nm-2500nm · Sizes: <5mm to >100mm
- Environmentally Rugged · Substrates: BK7, Fused Silica · Wavefront: <1/4 wave available
- Energy Density: Continuous Wave is 100 watts/cm2 with appropriate epoxy selection.
|
These VPHGs can be
customized for almost any wavelength or spatial frequency, are
environmentally rugged, and scratch resistant. Process
Instruments uses of our volume phase holographic gratings for their
diode laser systems.
We provide a high level
of customer service. Additionally, we offer consulting, design,
prototype, product integration, and quantity production at competitive
prices. For sales info contact 435-752-4301, email us, or send us a
completed Customer
Grating Worksheet.
|
·