Standard Ultrafast Laser Optics (120 – 150 nm Bandwidth)

Standard Ultrafast Laser Optics

The coatings shown here are calculated for a bandwidth of 120 – 150 nm in the wavelength range between 600 nm and 1000 nm
Very high reflectance of the mirrors (R > 99.99 %)
Spectral tolerance 1 %
In-house design calculation and GDD measurement capabilities
Center wavelength, GDD and TOD according to customer specifications
Measured GDD spectra available on request
All kinds of mirrors (e.g. Cavity mirrors, pump mirrors and turning mirrors)

LIDT Info
0.4 J/cm², 800 nm, 42 fs, 1 kHz, Ø 80 µm* 2 J/cm², 800 nm, 70 fs, 10 Hz, Ø 700 µm** For high power mirrors see page High Power Ultrafast Laser Optics (550 – 1100 nm).
* Measurements were performed at Wigner Research Centre for Physics, Budapest
** Measurements were performed at Helmholtz-Zentrum Dresden-Rossendorf

Cavity Mirrors AOI = 0°

Fig.1:Reflectance and GDD spectra of a standard low dispersion ultrafast laser mirror

a)Reflectance vs. wavelength

b)GDD vs. wavelength

All types of mirrors are also available with negative GDD (e.g. -40 fs²). For negative GDD mirrors or high dispersion mirrors see page High Dispersion Mirrors AOI = 0°.

Pump Mirrors AOI = 0°

Fig.2:Reflectance and GDD spectra of a standard low dispersion pump laser mirror

a)Reflectance vs. wavelength

b)GDD vs. wavelength

Turning Mirrors AOI = 45°

Fig.3:Reflectance and GDD spectra for a standard low dispersion turning mirror (bandwidth Ru (45°) > 99.9 % ≈ 160 nm)

a)Reflectance vs. wavelength

b)GDD vs. wavelength

Output Couplers AOI = 0°

Fig.4:Reflectance and GDD spectra of output couplers with a bandwidth of 120 nm

a)Reflectance spectra of several standard output couplers

b)GDD spectra of the output coupler with R = 98 %; GDD spectra are similar for all levels of reflectance

Beam Splitters for p-polarized light at AOI = 45°

Fig.5:Reflectance and GDD spectra of beam splitters for p-polarized light

a)Reflectance spectra of several standard beam splitters

b)GDD spectra of the beam splitter with R = 50 %; the GDD spectra are similar for all levels of reflectance

Beam Splitters for s-polarized light at AOI = 45°

Fig.6:Reflectance and GDD spectra of beam splitters for s-polarized light

a)Reflectance spectra of several standard beam splitters

b)GDD spectra of the beam splitter with R = 50 %; the GDD spectra are similar for all levels of reflectance

Reflectance and transmittance of output couplers and beam splitters can be adjusted according to customer specifications
Tolerances for output couplers:
- R = 10 % … 70 % ±2.5 %
- R = 70 % … 90 % ±1.5 %
- R = 90 % … 95 % ±0.75 %
- R = 95 % … 98 % ±0.5 %
- R > 98 % ±0.25 %
- R > 99 % ±0.1 %
Standard AR coatings:
- AOI = 0°: R < 0.2 %
- AOI = 45°: Rs or Rp < 0.2 %
- AOI = 45°: Rs ≈ Rp ≈ 0.5  %
- In case of p-polarization, uncoated rear side possible,
  Rp (Fused Silica, 45°) ≈ 0.6 %

Negative Dispersion Mirrors AOI = 0°

Fig.7:Reflectance and GDD spectra of a negative dispersion mirror with a bandwidth of 150 nm

a)Reflectance vs. wavelength

b)GDD vs. wavelength

High Dispersion Mirrors AOI = 0°

LAYERTEC also offers high dispersion mirrors for pulse compression in Ti:Sapphire lasers. These mirrors and mirror pairs show spectral bandwidths of 100 nm – 300 nm and negative GDD values of some hundred fs². Compared to prism compressors, high dispersion mirrors reduce the intra cavity losses enabling higher output power of the laser.

All high dispersion mirrors are designed according to customer specification. Please specify the amount GD which is to be compensated.

Fig.8:Reflectance and GDD spectra of a high dispersion mirror with a bandwidth of 120 nm and a GDD of -450 ±100 fs² in the 800 nm range

a)Reflectance vs. wavelength

b)Calculated GDD vs. wavelength

c)Measured GDD vs. wavelength

Matching measured and calculated GDD spectra prove the reliability of the coating process.

High Dispersion Mirror Pairs AOI = 0°

Fig.9:Reflectance and GDD spectra of a high dispersion mirror pair with a bandwidth of 200 nm and an average GDD of -120 ±40 fs² per bounce in the 800 nm range

a)Reflectance vs. wavelength

b)Calculated GDD vs. wavelength

c)Measured GDD vs. wavelength

Thin Film Polarizers for AOI = 55°

Fig.10:Reflectance and GDD spectra of a standard TFP (AOI = 55° to use the Brewster’s angle for the transmitted p-polarized light)

a)Reflectance vs. wavelength

b)GDD vs. wavelength

Thin Film Polarizers for AOI = 65°

The bandwidth of thin film polarizers can be extended if large angles of incidence are used. As shown in Fig. 11a polarizer bandwidth as large as 100 nm can be achieved. However, this is combined with a reduced reflectance for the s-polarized light especially at very large AOI (e.g. AOI=80°).