Create an Account  |   Log In

View All »Matching Part Numbers


Your Shopping Cart is Empty
         

Ultrafast Broadband Beamsplitters with Controlled Dispersion


  • Deterministic GDD for Femtosecond Laser Pulses
  • Designed for P-Polarized Light at 45° AOI
  • Infrasil® Windows Available to Balance GDD

UFBS2080

20:80 Ultrafast Beamsplitter
(600-1500 nm)

UFBS8020

80:20 Ultrafast Beamsplitter
(600 - 1500 nm)

Application Idea

UFBS5050 50:50 Ultrafast Beamsplitter in a POLARIS-K1T1 Kinematic Mount

UFBS9010

90:10 Ultrafast Beamsplitter
(600 - 1500 nm)

UFBS50502

50:50 Ultrafast Beamsplitter
(1000 - 2000 nm)

Related Items


Please Wait
Optic Cleaning Tutorial

Features

  • Deterministic Group Delay Dispersion (GDD) in Reflection and Transmission
  • Designed for P-Polarized Light Incident at 45°
  • Split Ratios:
    • 20:80, 50:50, 80:20, or 90:10 (R:T) for 600 - 1500 nm
    • 50:50 for 1000 - 2000 nm
  • Optimized for Femtosecond Ti:Sapphire and Yb Lasers
  • Infrasil® Windows to Balance GDD when Used with UFBS5050 Beamsplitter

Thorlabs' Ultrafast Broadband Beamsplitters offer a 20:80, 50:50, 80:20, or 90:10 (R:T) beamsplitting ratio over the 600 - 1500 nm wavelength range, or a 50:50 (R:T) beamsplitting ratio over the 1000 - 2000 nm wavelength range. They are designed to be used with p-polarized light incident at 45° and are not intended to be used for s-polarized light. For s-polarized or circularly polarized light applications, please see our full selection of plate beamsplitters. As shown by the images at the top of the page, each ultrafast beamsplitter is marked with an arrow that points toward the beamsplitting coating; light being split should be incident on this surface to obtain the intended performance. The wide usable wavelength range of these beamsplitters makes them compatible with femtosecond pulsed Ti:Sapphire, Yb, and Er fiber lasers. The beamsplitters have an AR coating on the back surface that provides <0.5% absolute reflectance over the same wavelength range as the beamsplitter coating. The Infrasil substrate is a type of optical quartz that has nearly identical dispersion to fused silica but higher internal transmission around 1380 nm.

Mounting Options
Our ultrafast beamsplitters and Infrasil windows are too thin for standard setscrew-based mounts. Hence, we recommend mounting them in retaining-ring-based mounts, such as our Polaris® SM1-threaded mounts or fixed optic mounts. Retaining rings apply less mechanical stress to the optic than setscrews, helping to prevent bending of the optical surfaces, which compromises performance. The 4.0 mm thick beamsplitters can also be mounted in our Polaris Low-Distortion Optic Mounts. Alternatively, the beamsplitters can be installed in a POLARIS-K1C4 glue-in kinematic mirror mount or a POLARIS-B1G glue-in fixed mount. The POLARIS-B1G features two cut-outs to maximize the transmissive clear aperture at 45° AOI, making it an ideal mount for a plate beamsplitter.

Balancing GDD in the Transmitted and Reflected Beam
When using the UFBS5050 ultrafast beamsplitter with pulses shorter than 50 fs, we recommend inserting one of our Infrasil windows into the reflected beam at a 0° angle of incidence in order to balance the GDD. We offer Infrasil windows in Ø1/2" (Item # UDP05) and Ø1" (Item # UDP10) sizes. The uncoated windows are 1.0 mm thick and have flat transmission from 300 nm to 3 µm, as shown in the table below. Using one of these windows reduces the GDD difference between the transmitted and reflected arms to <20 fs2 at 800 nm. Longer pulses have a narrow spectral bandwidth that negates the need for additional dispersion compensation. See the Group Delay tab for additional details. When using a 20:80 or an 80:20 ultrafast beamsplitter, our Infrasil windows are not thick enough to balance the dispersion exactly, but they will still improve dispersion matching between the beams. For thicker windows that can be used to compensate for dispersion in the 20:80 or 80:20 beamsplitters, see our selection of uncoated fused silica windows

Thorlabs' selection of ultrafast optics also includes low-GDD mirrors for 700 - 930 nm, 950 - 1170 nm, 1400 - 1700 nm, and 1760 - 2250 nm. For our full selection, please see the Ultrafast Optics tab.

Recommended Beam Geometry
Recommended Configuration for Balanced Dispersion in Transmitted and Reflected Beams of 50:50 Ultrafast Beamsplitter (Only Necessary for Sub-50 fs Pulses)

Balanced Group Delay for 50:50 Ultrafast Beamsplitter

The UFBS5050 Ultrafast Beamsplitter provides a 50:50 beamsplitting ratio for femtosecond laser pulses with well-defined, nearly equal group delay dispersion in the transmitted and reflected beams. For the shortest pulses (<50 fs), additional dispersion compensation is recommended, as detailed in the text below. Please note for the following discussion that Infrasil® and fused silica have nearly identical dispersion.

Transmitted Beam
When the UFBS5050 beamsplitter is oriented at a 45° incident angle, the transmitted pulse will be dispersed by traveling 1.7 mm through the Infrasil substrate (assuming the substrate is 1.5 mm thick). The plot below on the left compares the measured group delay through the UFBS5050 beamsplitter to the calculated group delay through 1.7 mm of Infrasil.

Reflected Beam
The beamsplitting coating is designed to impart on the reflected pulse the same amount of dispersion as traveling through 0.7 mm of fused silica. The plot below on the right shows that the measured group delay of the reflected beam is similar to the calculated group delay through 0.7 mm of fused silica, as expected. The measurement stops at 1100 nm due to limitations of the white light interferometer used for this test.

In order to balance the dispersion of the reflected beam with that of the transmitted beam, either of our Infrasil windows, which are 1.0 mm thick, can be inserted into the reflected beam at a 0° incident angle. This geometry is shown in the figure to the right. The window allows the net dispersion of the reflected beam to be the same as traveling through 1.7 mm of Infrasil. For pulses with narrow spectral bandwidth (i.e., pulses longer than 50 fs), the group delay dispersion varies slowly enough that this additional window is not necessary.

Measured Group Delay in Transmitted Beam
Click to Enlarge

Group Delay in Transmission
Measured Group Delay in Reflected Beam
Click to Enlarge

Group Delay in Reflection

Thorlabs offers a wide selection of optics optimized for use with femtosecond and picosecond laser pulses. Please see below for more information.


Posted Comments:
Kurtis Borne  (posted 2019-10-25 15:28:11.503)
I am very interested in purchasing the 90:10 ultrafast beamsplitter. It would be used with a 800 nm, 25 fs beam with a 2 mJ pulse energy (@ 10 kHz). All the specs seem appropriate, but obviously with these short wavelengths I'm very susceptible to GDD, and I am confused what it means in the provided plot for "reflected GDD." I don't understand the meaning of reporting a GDD for the reflected part of the beam and not the transmitted, and I am worried that the transmitted GDD would be much larger than the acceptable ~25fs^-2 that is reported . Please let me know if you have any information
YLohia  (posted 2019-10-28 03:23:03.0)
Thank you for contacting Thorlabs. The transmitted GDD of coatings is usually very small (i.e. < 10 fs^2), which is the case with the UFBS9010. So, the total transmitted GDD is just the material (Infrasil) dispersion.
ikb2  (posted 2017-07-12 11:18:10.77)
Considering using the beamsplitter/infrasil window combination in an interferometric setup. It seems that if the beams are retroreflected and recombined within the beamsplitter, then the two arms pick up different amounts of dispersion. The reflected beam reflects, passes twice through the infrasil window, then transmits, accumulating 4.4 mm worth of dispersion. The transmitted beam transmits through the beam splitter twice, reflects, and then transmits again, accumulating 5.8 mm worth of dispersion. Do you have a recommendation for working with this setup in the sub-100 fs regime?
tfrisch  (posted 2017-09-05 10:45:13.0)
Hello, thank you for contacting Thorlabs. It sounds like you are describing a Michelson configuration in which the arm which is reflected, then transmitted, has a different delay than the arm that is transmitted, then reflected. With the compensator plate, the R-R arm and T-T arm can be matched in delay, assuming the retroreflector displaces the beam by more than the beam diameter. A simpler solution might be to use a Mach-Zender configuration. I will reach out to you about this directly.
tug13936  (posted 2017-06-13 12:38:56.19)
Can you explain why this kind of beam splitter can not work for s-polarization? Can you send me any data for the testing with s-polarization?
tfrisch  (posted 2017-06-30 02:56:00.0)
Hello, thank you for contacting Thorlabs. The S-state has much worse performance because this was optimized for the P-state. I will reach out to you directly with some typical data.
elharel  (posted 2016-12-18 16:51:16.62)
Would it be possible to get a 80:20 version?
tfrisch  (posted 2016-12-20 02:49:15.0)
Hello, thank you for contacting Thorlabs. I will reach out to you directly with details on our custom coating capabilities.
m.c.ashby  (posted 2015-12-04 18:17:39.387)
Can this beamsplitter be used in reverse to combine two Ultrafast Ti:Sph beams? What is the dependence on polarization?
besembeson  (posted 2015-12-07 10:47:21.0)
Response from Bweh at Thorlabs USA: Yes you can use this in reverse direction, provided you are familiar with the issues related to phase-sensitivity when coherently combining two beams. If you are hoping to combine one S- and one P-polarized beam (and if the S-reflectivity is acceptable), then I'd suggest using the S-polarized beam in transmission because the dispersion is better behaved. Our UK division will share the S-polarized reflectivity example data with you.
sunryu  (posted 2015-06-17 01:55:25.563)
It would fit my application. What is the damage threshold? Is this safe for 4 W Ti:Sapphire oscillator output (140 fs, 80 MHz)?
jlow  (posted 2015-07-07 10:40:16.0)
Response from Jeremy at Thorlabs: We are going to be testing these in the near future and we will post the data to the web when the test is finished.
mastron  (posted 2015-05-18 20:09:34.93)
It would be nice if the "Low-GDD Ultrafast Beamsplitter for 600 - 1500 nm" and matched Infrasil windows came in Ø2" sizes. Also I'm not sure if I'm missing it somewhere but what is the power damage threshold for these optics?
jlow  (posted 2015-07-07 10:35:54.0)
Response from Jeremy at Thorlabs: We do not currently have a Ø2" version for these mirrors. The coating would severely bend the substrate and one could expect bad surface flatness so this may not be feasible for some applications. With regard to the damage threshold, we are going to be testing them in the near future and we will post the data to the web when the test is finished.

Controlled-GDD Ultrafast Beamsplitters, 600 - 1500 nm

Item # UFBS2080 UFBS5050 UFBS8020 UFBS9010
Overall Performance
Rabs = 20 ± 2%
Tabs = 80 ± 2%
Rabs = 50 ± 5%
Tabs = 50 ± 5%
Rabs = 80 ± 5%
Tabs = 20 ± 5%
Rabs = 90 ± 2%
Tabs = 10 ± 2%
Wavelength Range 600 - 1500 nm
AR Coating Rabs < 0.5% over 600 - 1500 nm
Diameter 1" (25.4 mm)
Diameter Tolerance +0.00/-0.10 mm
Thickness 1.5 mm 4.0 mm
Thickness Tolerance ±0.10 mm
Clear Aperture >80% of Diameter
Angle of Incidence (AOI) 45°
Laser-Induced
Damage Thresholda
0.18 J/cm2 (800 nm, 51 fs FWHM, P-Pol, 1000 Pulses) 0.17 J/cm2 (800 nm, 51 fs FWHM, P-Pol, 1000 Pulses) - -
Input Polarization P-Polarization
Surface Quality 15-5 Scratch-Dig 15-10 Scratch Dig
Surface Flatness <λ/5 Over Clear Aperture <3λ Over Clear Aperture <1λ Over Clear Apertureb <1λ Over Clear Aperturec
Parallelism ≤5 arcmin
Substrate Infrasil®
Reflectance/Transmission
Raw Data

Raw Data

Raw Data

Raw Data
Group Delay (GD) - Reflection

Raw Data
Transmission

Raw Data
Reflection

Raw Data
-
Group Delay Dispersion (GDD) - - - - Reflection

Raw Data
  • For ultrafast optics, the laser-induced damage threshold (LIDT) is defined as the fluence (per pulse) that produces visible damage after a given number of pulses. LIDT values are not guaranteed in the ultrashort pulse regime. As such, they are provided as a service to customers.
  • Measured at 632.8 nm
  • Measured at 633 nm
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
UFBS2080 Support Documentation
UFBS2080Customer Inspired! Ø1" 20:80 (R:T) Low-GDD Ultrafast Beamsplitter, 600 - 1500 nm, 45° AOI
$275.94
Today
UFBS5050 Support Documentation
UFBS5050Ø1" 50:50 (R:T) Low-GDD Ultrafast Beamsplitter, 600 - 1500 nm, 45° AOI
$275.94
Today
UFBS8020 Support Documentation
UFBS8020Customer Inspired! Ø1" 80:20 (R:T) Low-GDD Ultrafast Beamsplitter, 600 - 1500 nm, 45° AOI
$307.66
Today
UFBS9010 Support Documentation
UFBS9010Customer Inspired! Ø1" 90:10 (R:T) Low-GDD Ultrafast Beamsplitter, 600 - 1500 nm, 45° AOI
$375.95
Today

Controlled-GDD Ultrafast Beamsplitters, 1000 - 2000 nm

Item # UFBS50502
Overall Performance
Rabs = 50 ± 5%
Tabs = 50 ± 5%
Wavelength Range 1000 - 2000 nm
AR Coating Rabs < 0.5% over 1000 - 2000 nm
Diameter 1" (25.4 mm)
Diameter Tolerance +0.00/-0.10 mm
Thickness 4.0 mm
Thickness Tolerance ±0.10 mm
Clear Aperture >80% of Diameter
Angle of Incidence (AOI) 45°
Laser-Induced
Damage Threshold
-
Input Polarization P-Polarization
Surface Quality 15-10 Scratch-Dig
Surface Flatness <2λ Over Clear Aperturea
Parallelism ≤5 arcmin
Substrate Infrasil®
Reflectance/Transmission
Raw Data
Group Delay (GD) Reflection

Raw Data
Transmission

Raw Data
  • Measured at 633 nm
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
UFBS50502 Support Documentation
UFBS50502Ø1" 50:50 (R:T) Low-GDD Ultrafast Beamsplitter, 1000 - 2000 nm, 45° AOI
$324.45
Today

Infrasil® Windows, Uncoated

Recommended Beam Geometry
Recommended Configuration for Balanced Dispersion in Transmitted and Reflected Beam of 50:50 Ultrafast Beamsplitter (Only Necessary for Sub-50 fs Pulses)
Item # UDP05 UDP10
Diameter  1/2" (12.7 mm) 1" (25.4 mm)
Diameter Tolerance +0.0 / -0.1 mm
Thickness 1.0 mm
Thickness Tolerance ±0.1 mm
Clear Aperture >90% of Diameter >80% of Diameter
Parallelism <5 arcmin
Transmitted Wavefront Errora λ/10 Over Clear Aperture
Surface Quality 10-5 Scratch-Dig
Wavelength Range 300 nm - 3 µm (Uncoated)
Substrate Infrasil®
Transmission Data
Raw Data
  • Measured at 633 nm
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
UDP05 Support Documentation
UDP05Ø1/2" Infrasil® Window, t = 1.0 mm
$77.37
Today
UDP10 Support Documentation
UDP10Ø1" Infrasil® Window, t = 1.0 mm
$88.47
Today
Log In  |   My Account  |   Contact Us  |   Careers  |   Privacy Policy  |   Home  |   FAQ  |   Site Index
Regional Websites: West Coast US | Europe | Asia | China | Japan
Copyright 1999-2019 Thorlabs, Inc.
Sales: 1-973-300-3000
Technical Support: 1-973-300-3000


High Quality Thorlabs Logo 1000px:Save this Image

Last Edited: Apr 24, 2014 Author: Dan Daranciang