Products Home / Optical Elements / Optical Mirrors / Dichroic Beamsplitters / Harmonic Beamsplitters with Low Group Delay DispersionHarmonic 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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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 |
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. |
Thorlabs offers a wide selection of optics optimized for use with femtosecond and picosecond laser pulses. Please see below for more information.
| Low GDD Mirrors | |||||
|---|---|---|---|---|---|
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| 355 - 445 nm | 460 - 590 nm | 700 - 930 nm | 950 - 1170 nm | 1400 - 1700 nm | 1760 - 2250 nm |
| Metallic Mirrors | Dielectric Mirror | High-Power Mirrors for Picosecond Lasers |
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|---|---|---|---|---|
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| Ultrafast-Enhanced Silver Mirrors, 750 - 1000 nm |
Protected Silver Mirrors, 450 nm - 20 µm |
Unprotected Gold Mirrors, 800 nm - 20 µm |
Dual-Band Dielectric Mirror, 400 nm and 800 nm |
Ytterbium Laser Line Mirrors, 250 nm - 1080 nm |
| Dispersion-Compensating Optics | Low-GDD Harmonic Beamsplitters |
Deterministic GDD Beamsplitters |
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|---|---|---|---|
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| Dispersion-Compensating Mirrors, 650 - 1050 nm |
Dispersion-Compensating Prisms, 700 - 900 nm |
Harmonic Beamsplitters, 400 nm and 800 nm or 500 nm and 1000 nm |
Beamsplitters & Windows, 600 - 1500 nm or 1000 - 2000 nm |
Zoom| 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 | ||||
Zoom| 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 |
Low-GDD, Harmonic Beamsplitter for Ti:Sapph Lasers