Low GDD Ultrafast Mirrors for 1760 nm - 2250 nm

High Reflectance Over 1760 nm - 2250 nm
Group Delay Dispersion < 30 fs²
Ideal for Femtosecond Thulium (Tm)
and Holmium (Ho) Lasers

UM10-45D

Ø1"

UM05-45D

Ø1/2"

Application Idea

UM05-45D Low GDD Mirror in a
POLARIS-K05F1 Low-Distortion Mount
and Mounted with a POLARIS-CA1
Clamping Arm

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Overview
Graphs
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Ultrafast Optics

Item #	UM05-45D	UM10-45D
Design Wavelength Range	1760 - 2250 nm
Diameter	1/2" (12.7 mm)	1" (25.4 mm)
Diameter Tolerance	+0.00 / -0.10 mm
Thickness	6.4 mm (0.25")	9.5 mm (0.37")
Thickness Tolerance	±0.20 mm
Clear Aperture	>80% of Diameter
Reflectance	R_s > 99% (1760 - 2250 nm) R_p > 99% (1900 - 2050 nm)
Angle of Incidence	45°
Group Delay Dispersion	\|GDD_s\| < 30 fs² (1760 - 2250 nm) \|GDD_p\| < 30 fs² (1900 - 2050 nm)
Substrate	Fused Silica
Front Surface Flatness	λ/6 at 632.8 nm Over Clear Aperture	λ/4 at 632.8 nm Over Clear Aperture
Front Surface Quality	15-5 Scratch-Dig
Parallelism	≤3 arcmin
Back Surface	Polished

Features

Low Group Delay Dispersion: |GDD| <30 fs²
Ideal for Pulses Shorter than 250 fs
Reflectance Greater than 99%
Ø1/2" and Ø1" Mirrors Available

Thorlabs' Low Group Delay Dispersion (GDD) Mirrors feature a coating designed for high reflectance in the 1760 nm - 2250 nm range. The wavelength range is optimized for lasers around 2 µm in wavelength, such as thulium (Tm) and holmium (Ho) doped lasers. These mirrors are ideal for applications where pulse broadening is a concern and are designed for a 45° angle of incidence. The dielectric coating is applied with an ion-beam-sputtering (IBS) technique, providing a highly controlled and durable dielectric thin film coating.

These mirrors offer an ideal combination of greater than 99% reflectance and less than |30 fs²| GDD. For details, please see the Graphs tab.

Our low GDD mirrors are available with either a 1/2" or 1" diameter. The edge of each optic is engraved with the item number and an arrowhead pointing to the coated surface. The back surface of these mirrors is polished so that the small percentage of light that leaks through the reflective coating may be used for applications such as power monitoring.

In addition to these mirrors for 1760 - 2250 nm, Thorlabs also offers Low GDD Mirrors for various other wavelength ranges. For our full selection of optics for ultrafast applications, please see the Ultrafast Optics tab.

The graphs below are measured and theoretical results of the reflectance and the group delay dispersion, respectively, at an AOI of 45°.

Click to Enlarge
Click for Raw Data
The shaded region represents the specified wavelength range where R_S>99%.

Click to Enlarge
Click for Raw Data
The shaded region represents the specified wavelength range where S-Polarization GDD<|30 fs²|. The GDD values fluctuate rapidly outside of this region.

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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

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

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

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