Low GDD Ultrafast Mirrors for 355 - 445 nm

Ideal for Second Harmonic of Femtosecond Ti:Sapphire Lasers
Designed for 355 - 445 nm
Group Delay Dispersion < 30 fs²

UM05-45U

(Ø1/2")

UM10-45U

(Ø1")

Application Idea

UM05-45U Low GDD Mirror in a
POLARIS-K05 Mirror Mount

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Ultrafast Optics

Item #	UM05-45U	UM10-45U
Design Wavelength Range	355 - 445 nm
Diameter	1/2" (12.7 mm)	1" (25.4 mm)
Diameter Tolerance	+0.00 mm / -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% (355 - 445 nm) R_p > 99% (370 - 425 nm)
Angle of Incidence	45°
Group Delay Dispersion	\|GDD_s\| < 30 fs² (355 - 445 nm) \|GDD_p\| < 30 fs² (370 - 425 nm)
Laser Induced Damage Threshold^a	0.081 J/cm² (400 nm, 55 fs FWHM, S-Pol, 1 Pulse) 0.062 J/cm² (400 nm, 55 fs FWHM, S-Pol, 10000 Pulses)
Substrate	Fused Silica
Front Surface Flatness	λ/10 at 632.8 nm Over Clear Aperture
Front Surface Quality	15-5 Scratch-Dig
Parallelism	≤3 arcmin
Back Surface	Polished

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. See the Graphs tab for a plot of LIDT as a function of the number of incident pulses.

Features

Designed for Frequency-Doubled Ultrafast Ti:Sapphire Laser Pulses
Ideal for Laser Pulses Shorter than 250 fs
Reflectance Greater than 99%
Low Group Delay Dispersion: |GDD| < 30 fs²
Available in Ø1/2" and Ø1" Sizes
For Use at a 45° Incident Angle

These Low Group Delay Dispersion (GDD) Mirrors provide high reflectance and low group delay dispersion in the 355 - 455 nm range (see the table to the right and the Graphs tab for details). This wavelength range is centered about 400 nm, making the mirrors ideal for the second harmonic of femtosecond Ti:Sapphire lasers. Designed for use at a 45° angle of incidence, their low GDD of <|30 fs²| helps prevent broadening of the incident pulse.

The ultrafast mirrors are available in 1/2" and 1" diameters. The edge of each optic is engraved with the item number and an arrowhead pointing to the coated surface, as shown in the photos above. Please note that the fundamental of the Ti:Sapphire laser will leak through the mirror substrate; the back surface of these mirrors is polished so that an appropriate beam trap, such as the BT610 (BT610/M) Beam Trap, can be used to absorb this through beam. If you wish to keep the fundamental in the beam path, please consider our dual-band ultrafast mirror.

In addition to these mirrors for 355 - 445 nm, Thorlabs 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 plots below give the theoretically calculated reflectance and group delay dispersion (GDD) of these mirrors at a 45° AOI and represent the designed performance. The actual performance will vary from lot to lot within the specifications given in the Overview tab.

Click to Enlarge
Click for Raw Data for 300 - 1000 nm
The shaded region in this plot denotes the wavelength range over which we guarantee R_s> 99%.

Click to Enlarge
Click for Raw Data for 300 - 1000 nm
The shaded region in this plot denotes the wavelength range over which we guarantee <|30 fs²| GDD for s-polarized light. The GDD fluctuates rapidly outside of this wavelength range.

Click to Enlarge
The laser induced damage threshold (LIDT) value of an ultrafast optic is defined as the fluence (per pulse) that produces visible damage after a given number of pulses. These LIDT values were measured with 55 fs FWHM pulses at 400 nm that were s-polarized and incident at 45°.

Posted Comments:

Arne Held (posted 2024-08-14 12:20:48.26)

Hi, is there a reason this mirror is so thick? Usually, 1" mirrors have a thickness of about 6.35mm. Also, most mirror mounts I can find are designed for 6.35mm thick mirrors. These mirrors would stick out of the mounts quite a lot. Best regards Arne Held

jpolaris (posted 2024-08-19 11:28:22.0)

Thank you for contacting Thorlabs. The UM10-45U and UM05-45U ultrafast mirrors use IBS-deposited thin films, which produce a substantial amount of mechanical stress on the substrate. To reduce the amount of deformation on the optic, we use a thicker substrate for the Ø1" mirror (UM10-45U). If a thinner substrate was used, an additional stress-compensation coating to the opposite face would also need to be applied.

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	970 - 1150 nm	1400 - 1700 nm	1760 - 2250 nm

Dielectric Mirror	High-Power Mirrors for Picosecond Lasers	Metallic Mirrors			Low-GDD Pump-Through Mirrors

Dual-Band Dielectric Mirror, 400 nm and 800 nm	Ytterbium Laser Line Mirrors, 250 nm - 1080 nm	Ultrafast-Enhanced Silver Mirrors, 750 - 1000 nm	Protected Silver Mirrors, 450 nm - 20 µm	Unprotected Gold Mirrors, 800 nm - 20 µm	Pump-Through Mirrors, 1030 - 1080 nm and 940 - 980 nm

Deterministic GDD Beamsplitters	Low-GDD Harmonic Beamsplitters	Low-GDD Polarizing Beamsplitters	β-BBO Crystals	Dispersion-Compensating Optics

Beamsplitters & Windows, 600 - 1500 nm or 1000 - 2000 nm	Harmonic Beamsplitters, 400 nm and 800 nm or 500 nm and 1000 nm	High-Power, Broadband, High Extinction Ratio Polarizers, 700 - 1300 nm	β-BBO Crystals for Second Harmonic Generation	Dispersion-Compensating Mirrors, 650 - 1050 nm	Dispersion-Compensating Prisms, 700 - 900 nm