Harmonic Beamsplitters with Low Group Delay Dispersion


  • Harmonic Separators for Ultrafast Ti:Sapphire or Yb Lasers
  • Separate Second Harmonic from Fundamental
  • High Suppression Ratio of Reflected Fundamental
  • Designed for 56° AOI

Our harmonic beamsplitters separate the fundamental and second harmonic of Ti:Sapphire or Yb lasers (not to scale).

UBS24

Ø1", Reflects 500 - 550 nm,
Transmits 1000 - 1100 nm

UBS21

25 mm Elliptical,
Reflects 360 - 440 nm,
Transmits 700 - 900 nm

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Fixed Polaris Beamsplitter Mount
Click to Enlarge
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Item #QtyDescription
POLARIS-B1S1Polaris Ø1" Flexure-Clamp Fixed Mount, Optimized for Beamsplitters
UBS201Ø1" Low-GDD Beamsplitter for Second Harmonic of Ultrafast Ti:Sapphire Lasers
POLARIS-CA11Flexure Clamping Arm for Ø1" Posts, Non-Bridging, Stainless Steel, 1.30" Counterbored Slot, 1/4"-20 Clamping Screw
PLS-P11Ø1" Post for Polaris Mirror Mounts, One 8-32 Mounting Hole, L = 1.00"
View Metric Product List
Item #QtyDescription
POLARIS-B1S1Polaris Ø1" Flexure-Clamp Fixed Mount, Optimized for Beamsplitters
UBS201Ø1" Low-GDD Beamsplitter for Second Harmonic of Ultrafast Ti:Sapphire Lasers
PLS-P246/M1Ø25.0 mm Post for Polaris Mirror Mounts, One M4 Mounting Hole, L = 24.6 mm
POLARIS-CA25/M1Flexure Clamping Arm for Ø25 mm Posts, Non-Bridging, Stainless Steel, 33.0 mm Counterbored Slot, M6 Clamping Screw
UBS20 Round Beamsplitter in a
POLARIS-B1S Flexure-Clamp Mount
Ultrafast Dichroic Brewster's Window
Click to Enlarge

UBS21 Elliptical Beamsplitter in a
BW25M Brewster's Angle Mount

Features

  • Harmonic Beamsplitters for Ultrafast Lasers:
    • Reflect Ti:Sapphire 2nd Harmonic (360 - 440 nm), Transmit Fundamental (700 - 900 nm)
    • Reflect Ytterbium Laser 2nd Harmonic (500 - 550 nm), Transmit Fundamental (1000 - 1100 nm)
  • Low Group Delay Dispersion (GDD): < 20 fs2 Over Reflected Wavelength Range
  • Round Format or Elliptical Format for Circular Aperture at 56° AOI

Thorlabs' ultrafast harmonic beamsplitters, also known as harmonic separators, are designed to separate the fundamental and second harmonic of light from an ultrafast Ti:Sapphire or ytterbium laser. Each optic features a coating designed for high reflectance of s-polarized light in the second harmonic wavelength range and low reflectance of p-polarized light in the fundamental wavelength range. The coatings are designed for use at a 56° angle of incidence (AOI) to minimize the reflectance of the fundamental component, though they may also be used at 45° with diminished performance. These beamsplitters are ideal for femtosecond pulsed lasers where pulse broadening is a concern by offering less than 20 fs2 absolute GDD.

The beamsplitter coating is applied to one surface of the substrate, while the other surface is uncoated. The edge of each round substrate (item #s UBS20 and UBS24) is engraved with the item # and an arrow indicating the coated side of the beamsplitter. The coated side of the elliptical UBS21 beamsplitter may be determined through visual inspection.

These beamsplitters are offered in round or elliptical variants. The elliptical substrate offers a larger clear aperture than the round substrate when mounted at 56° AOI. We recommend mounting Ø1" round beamsplitters in our POLARIS-B1G or POLARIS-B1S Polaris Mounts. For mounting 25 mm elliptical beamsplitters, we offer the BW25M Brewster's Angle Mount. Please refer to the photos above.

Thorlabs also offers a wide selection of ultrafast mirrors and beamsplitters. Additionally, we offer harmonic beamsplitters for Nd:YAG applications.

Specificationsa
Item # UBS20 UBS21 UBS24
Reflected Harmonic Second Harmonic of Ti:Sapphire Lasers Second Harmonic of Ytterbium Lasers
Optic Shape Round Elliptical Round
Diameter 1" (25.4 mm) Minor: 25.0 mm (0.98")
Major: 44.2 mm (1.74")
1" (25.4 mm)
Reflection Band
(Click for Plot)
360 - 440 nm, Rs > 98.5% 500 - 550 nm, Rs > 99%
Transmission Band
(Click for Plot)
700 - 900 nm, Rp < 0.3% 1000 - 1100 nm, Rp < 0.5%
Group Delay Dispersion
(Click for Plot)
|GDD| < 20 fs² (360 - 440 nm) |GDD| < 20 fs² (500 - 550 nm)
Angle of Incidence (AOI) 56°
Clear Aperture >80% of Diameter
Diameter Tolerance +0.00/-0.20 mm Minor: +0.00/-0.10 mm
Major: N/A
+0.0/-0.2 mm
Thickness 4.0 mm 2.0 mm 4.0 mm
Thickness Tolerance ±0.4 mm ±0.10 mm ±0.4 mm
Surface Quality 20-10 Scratch-Dig
Surface Flatnessb λ/10 @ 632 nm 2λ @ 632 nm <λ/10 @ 633 nm
Parallelism ≤5 arcmin ≤5 arcsec ≤5 arcmin
Substrate UV Fused Silicac IR Fused Silica
Mass 6 g 4 g 4 g
  • All Specifications @ 56° AOI
  • Specified Over Clear Aperture
  • Click Link for Detailed Specifications on the Substrate

Click here for measured data.
This measured data applies to our UBS20 and UBS21 beamsplitters, which were designed for use at a 56° angle of incidence.
Values are typical and will vary from lot to lot. The blue shaded regions denote the wavelength ranges over which the reflectance and GDD are specified.

 

Click here for theoretical data.
This theoretical data applies to our UBS24 beamsplitter, which was designed for use at a 56° angle of incidence.
Values are typical and will vary from lot to lot. The blue shaded regions denote the wavelength ranges over which the reflectance and GDD are specified.


Posted Comments:
Tom Dzelzainis  (posted 2021-07-19 12:41:47.573)
Hi, The graphs provided are for 56 deg angle of incidence. I was just wondering if you had any data available for 45 degree angle of incidence performance? Many thanks, Tom.
YLohia  (posted 2021-07-26 11:40:11.0)
Hello, thank you for contacting Thorlabs. The plot will redshift, and the performance will degrade, but unfortunately, we don't have enough test data to accurately estimate how much of an impact there will be across multiple production lots since the coating is not designed for a 45 deg AOI.
user  (posted 2021-06-11 11:34:54.547)
The perfectly inverse color coding on these plots compared to the actual wavelength of light is incredibly confusing. I know that they are labelled.
tcampbell  (posted 2021-06-15 09:38:44.0)
Hello, thank you for contacting Thorlabs. We understand the confusion from this. We have swapped the colors so that the red curves represent the red and infrared regions, while the blue curves represent the ultraviolet, blue, and green regions.
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Harmonic Beamsplitters for Ti:Sapphire Lasers

Key Specsa
Item # Reflected Harmonic Optic Size Reflection Band
(Click for Plot)
Transmission Band
(Click for Plot)
Group Delay Dispersion Thickness
UBS20 Second Harmonic of
Ti:Sapphire Lasers
Ø1" 360 - 440 nm, Rs > 98.5% 700 - 900 nm, Rp < 0.3% |GDD| < 20 fs² (360 - 440 nm) 4.0 mm
UBS21 25 mm Ellipticalb 2.0 mm
  • All specifications @ 56° AOI; see the Specs tab for complete specifications.
  • Ø25 mm @ 56° AOI; Minor Diameter: 25.0 mm, Major Diameter: 44.2 mm.
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
UBS20 Support Documentation
UBS20Customer Inspired! Ø1" Low-GDD Beamsplitter for Second Harmonic of Ultrafast Ti:Sapphire Lasers
$266.68
Today
UBS21 Support Documentation
UBS2125 mm Elliptical Low-GDD Beamsplitter for Second Harmonic of Ultrafast Ti:Sapphire Lasers
$350.22
Today
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Harmonic Beamsplitter for Yb Lasers

Key Specsa
Item # Reflected Harmonic Optic Size Reflection Band
(Click for Plot)
Transmission Band
(Click for Plot)
Group Delay Dispersion
(Click for Plot)
Thickness
UBS24 Second Harmonic of
Ytterbium Lasers
Ø1" 500 - 550 nm, Rs > 99% 1000 - 1100 nm, Rp < 0.5% |GDD| < 20 fs² (500 - 550 nm) 4.0 mm
  • All specifications @ 56° AOI; see the Specs tab for complete specifications.
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
UBS24 Support Documentation
UBS24Ø1" Low-GDD Beamsplitter for Second Harmonic of Ultrafast Yb Lasers
$267.75
Today