Saturable Absorber (SAM)

STB Series Saturable Absorber Mirrors (SAM)

Saturable absorber mirrors are Bragg-mirrors with AlAs/GaAs quarter-wave stacks, grown on GaAs wafers with one or more low temperature GaAs (LT-GaAs) or LT-InGaAs films as saturable absorbers.

Our saturable absorber mirrors with carrier relaxation times in the picosecond range can be used for passive mode-locking and Q-switching of diode-pumped lasers. The design of the thin film stack can be adjusted to meet the requirements of different passively mode-locked lasers in the picosecond and femtosecond region.

STB-SAM order information: Part-No description: STB-SAM-λ-A-τ-x

• λ - laser wavelength
• A - low intensity absorption
• τ - absorber relaxation time
• x - mounting condition (please see mounting conditions)

Product Ranges:

• Wavelength region 790 nm ... 830 nm: 800 nm
• Wavelength region 910 nm ... 990 nm: 920 nm | 940 nm | 980 nm
• Wavelength region 1020 nm ... 1150 nm: 1040 nm | 1064 nm | 1100 nm
• Wavelength region 1110 nm ... 1320 nm: 1150 nm | 1300 nm
• Wavelength region 1320 nm ... 1460 nm: 1340 nm | 1420 nm
• Wavelength region 1470 nm ... 1660 nm: 1510 nm | 1550 nm | 1645 nm
• Wavelength region 1900 nm ... 2600 nm: 2000 nm | 2400 nm
• Wavelength region 2700 nm ... 3200 nm: 2800 nm | 3000 nm

Mounting conditions

x = 4.0-0

• Single chip, unmounted
• Chip area 4.0 mm x 4.0 mm
• Chip thickness 450 µm

x = 1.0b-0

• Batch of 4 unmounted chips
• Chip area 1.0 mm x 1.0 mm
• Chip thickness 450 µm

x = 1.3b-0

• Batch of 4 unmounted chips
• Chip area 1.3 mm x 1.3 mm
• Chip thickness 450 µm

x = 4.0-12.7g-c / 4.0-12.7g-e

• Chip area 4.0 mm x 4.0 mm
• Glued on a copper heat sink with 12.7 mm diameter
• Center mounted : x = 4.0-12.7g-c
• Edge mounted : x = 4.0-12.7g-e

x = 4.0-12.7s-c / 4.0-12.7s-e

• Chip area 4.0 mm x 4.0 mm
• Soldered on a copper heat sink with 12.7 mm diameter
• Center mounted : x = 4.0-12.7s-c
• Edge mounted : x = 4.0-12.7s-e

x = 4.0-25.0g-c / 4.0-25.0g-e

• Chip area 4.0 mm x 4.0 mm
• Glued on a copper heat sink with 25.0 mm diameter
• Center mounted : x = 4.0-25.0g-c
• Edge mounted : x = 4.0-25.0g-e

x = 4.0-25.0s-c / 4.0-25.0s-e

• Chip area 4.0 mm x 4.0 mm
• Soldered on a copper heat sink with 25.0 mm diameter
• Center mounted : x = 4.0-25.0s-c
• Edge mounted : x = 4.0-25.0s-e

x = 4.0-25.4g-c / 4.0-25.4g-e

• Chip area 4.0 mm x 4.0 mm
• Glued on a copper heat sink with 25.4 mm diameter
• Center mounted : x = 4.0-25.4g-c
• Edge mounted : x = 4.0-25.4g-e

x = 4.0-25.4s-c / 4.0-25.4s-e

• Chip area 4.0 mm x 4.0 mm
• Soldered on a copper heat sink with 25.4 mm diameter
• Center mounted : x = 4.0-25.4s-c
• Edge mounted : x = 4.0-25.4s-e

x = 4.0-25.0w-c / 4.0-25.0w-e

• Chip area 4.0 mm x 4.0 mm
• Soldered on a water cooled copper heat sink with 25.0 mm diameter
• Center mounted : x = 4.0-25.0w-c
• Edge mounted : x = 4.0-25.0w-e

x = 4.0-25.0h-c / 4.0-25.0h-e

• Chip area 4.0 mm x 4.0 mm
• Thin film soldered on a water cooled copper heat sink with 25.0 mm diameter for high power application.
• Center mounted : x = 4.0-25.0h-c
• Edge mounted : x = 4.0-25.0h-e

x = FC/(A)PC-SMF

• Mounted on a 1 m long single mode fiber.
• Available fibers: 780HP
• FC/PC connector: x = FC/PC-SMF
• FC/APC connector: x = FC/APC-SMF

x = FC/(A)PC-PMF

• Mounted on a 1 m long polarization maintaining fiber.
• Available fibers: Panda PM780-HP
• FC/PC connector: x = FC/PC-PMF
• FC/APC connector: x = FC/APC-PMF

STB Series Resonant Saturable Absorber Mirrors

The resonant saturable absorber mirror (RSAM) is designated to reshape an optical signal. An optical signal which propagates in optical fibers, communication nodes and other optical devices is subject to optical losses and is modified. After every amplification stage, which uses the stimulated optical emission process, the signal to noise ratio decreases as a result of the inevitable spontaneous emission.

The RSAM, included after an optical amplifier, decreases the noise floor and allows to pass the optical pulses unaffected due to the nonlinear-optical behavior.

Part-No description: RSAM-λ-τ-x

• λ - laser wavelength
• τ - absorber relaxation time
• x - mounting condition

STB Series Saturable Output Couplers (SOC)

Using a saturable output coupler (SOC), a self-starting, passively mode-locked or Q-switched diode-pumped solid-state or fiber laser with a very simple layout can be arranged. The SOC is a combination of a saturable absorber mirror (SAM) with an output coupler.

SOC order information: Part-No description: STB-SOC-λ-A-T-τ-x

• λ - laser wavelength
• A - low intensity absorption
• T - low intensity transmittance
• τ - absorber relaxation time
• x - mounting condition

Saturable Noise Suppressor (SANOS)

The resonant saturable absorber mirror (RSAM) is designated to reshape an optical signal. An optical signal which propagates in optical fibers, communication nodes and other optical devices is subject to optical losses and is modified. After every amplification stage, which uses the stimulated optical emission process, the signal to noise ratio decreases as a result of the inevitable spontaneous emission.

The RSAM, included after an optical amplifier, decreases the noise floor and allows to pass the optical pulses unaffected due to the nonlinear-optical behavior.

1. Free-space Saturable Noise Suppressor

For 1064 nm wavelength we offer a free-space saturable noise suppressor: FS-SANOS. It consists of a RSAM and a 100% mirror and allows the insertion into a laser beam without change of the beam direction.

Free space SANOS order information: Part-No description: STB-FS-SANOS-λ-τ-x

• λ - laser wavelength
• τ - absorber relaxation time
• x - number of absorber stages (1 or 2)

SANOS applications

• Suppression of noise (ASE – amplified spontaneous emission) after an optical amplifier
• Suppression of remaining pulses after a pulse picker

1.1 Free-space SANOS @ 1064 nm with One RSAM

One stage STB-FS-SANOS-1064-15ps-1

A STB-FS-SANOS consists of a resonant saturable absorber mirror (RSAM) and a conventional 100% mirror. The beam goes true the FS-SANOS without changing of the direction, but with a parallel offset of 2 mm. The RSAM has a strong non-linear reflectance. For a low input signal level the transmittance of the STB-FS-SANOS is only 2 % (98 % loss), whereas high intensity pulses are transmitted with a lower loss of 50 %. The input is isolated better than 50 dB. To meet exactly the low-intensity reflectance minimum the input beam inclination can be changed by some degrees.

Main STB-FS-SANOS data:

• Resonance wavelength: 1064 nm ( 1050 nm – 1064 nm on request)
• Full width at half maximum FWHM: 20 nm
• Noise suppression ratio: 14 dB
• Insertion loss: 3 dB
• Saturation fluence: 4 μJ/cm2 @ noise suppression of 10 dB
• Relaxation time constant: 15 ps
• Parallel beam offset: 2 mm
• Mirrors: one RSAM and one dielectric mirror with R > 99%, size: 4 mm x 4 mm
• Angle of incidence on mirrors: 8°

1.2 Two stage STB-FS-SANOS-1064-9ps-2

A STB-FS-SANOS-2 consists of two resonant saturable absorber mirrors (RSAM). The beam goes true the free-space SANOS without changing of the direction, but with a parallel offset of 2 mm. The RSAM has a strong non-linear reflectance. For a low input signal level the transmittance of the STB-FS-SANOS-2 is lower than 0,1% (99,9 % loss), whereas high intensity pulses are transmitted with a lower loss of 75 %. The input is isolated better than 50 dB. To meet exactly the low-intensity reflectance minimum the input beam inclination can be changed by some degrees.

Main FS-SANOS data

• Resonance wavelength: 1064 nm
• Full width at half maximum FWHM: 17 nm
• Noise suppression ratio: > 20 dB
• Insertion loss: 6 dB
• Saturation fluence : 10 μJ/cm2 @ noise suppression of 20 dB
• Relaxation time constant: 15 ps
• Parallel beam offset: 2 mm
• Mirrors: two RSAM, size: 4 mm x 4 mm
• Angle of incidence on mirrors: 8°

2. Fiber-coupled Saturable Noise Suppressor

For 1550 nm wavelength we offer a fiber coupled saturable noise suppressor: FC-SANOS. It consists of a RSAM on the second port of a three port circulator and allows simple insertion into a fiber.

Fiber coupled SANOS order information: Part-No description: STB-FC-SANOS-λ-x

• λ - laser wavelength
• x - fiber and connector type

A SANOS is a resonant saturable absorber mirror (RSAM), mounted on a circulator. The RSAM has a strong non-linear reflectance. For a low input signal level the transmittance of the FC-SANOS is only 3% (97% loss), whereas high intensity pulses are transmitted with a lower loss of 50%. The needed peak pulse power for saturation is about 500 mW. Because the RSAM is a resonant device, the noise is only suppressed at the resonance wavelength. The common fiber connector type is FC/PC, but it can be customized. The input isolation is better than 50 dB.

• Part number: STB-FC-SANOS-15XX
• Resonance wavelength: 1530 nm, 1535 nm, … ,1555 nm, 1560 nm in steps of 5 nm
• Full width at half maximum FWHM: 16 nm
• Low intensity transmittance: 3 %
• High intensity transmittance: 45 %
• Noise suppression factor: 6 … 18 (dependent on the input signal/noise ratio)
• Insertion loss: 3 dB
• Pulse fluence: F = 100 μJ/cm2
• Relaxation time constant : ~ 5 ps
• Maximum mean input power: 0.5 W
• Directivity: 50 dB
• Fiber connector type: FC/PC, other on request

Saturable Absorber in Transmission (SA)

The saturable absorber without a Bragg-mirror can be used for self-starting, passively mode-locking of a laser in a similar way as a SAM, but it is working in transmission mode. It can be inserted for instance into a fiber ring laser. The saturatioon fluence of a SA is substantial higher than that of a SAM.

SA order information: Part-No description: STB-SA-λ-A-τ-x

• λ - laser wavelength
• A - low intensity absorption
• τ - absorber relaxation time
• x - mounting condition

1. Part number: STB-SA-1020-40-x at wavelength 1020 nm

• Laser wavelength: 980 nm … 1040 nm
• Absorptance: 40 %
• Modulation depth: 25 %
• Non-saturable loss: 15 %
• Saturation fluence: 300 μJ/cm2
• Pulse damage threshold: 1.2 mJ/cm2
• Relaxation time constant: ~ 500 fs
• Chip area: 5mm x 5mm; other dimensions on request
• Chip thickness: 625 μm; semi-insulating GaAs

2. Part number: STB-SA-1030-34-3ps-x at wavelength 1030nm

• Laser wavelength: 1000 nm … 1040 nm
• Absorptance: 34 %
• Modulation depth: 20 %
• Non-saturable loss: 14 %
• Saturation fluence: 300 μJ/cm2
• Pulse damage threshold: 1.2 mJ/cm2
• Relaxation time constant: ~ 3 ps
• Chip area: 5mm x 5mm; other dimensions on request
• Chip thickness: 450 μm; semi-insulating GaAs

3. Part number: STB-SA-1064-14-28ps-x at wavelength 1064 nm

• Laser wavelength: 1000 nm … 1100 nm
• Absorptance: 14 %
• Transmittance: 85 %
• Modulation depth: 3.4 %
• Saturation fluence: 300 μJ/cm2
• Damage threshold : 200 MW/cm2
• Relaxation time constant: ~ 28 ps
• Chip area: 5.0 mm x 5.0 mm; other dimensions on request
• Chip thickness: 625 μm; semi-insulating GaAs

4. Part number STB-SA-1064-25-500fs-x at wavelength 1064 nm

• Laser wavelength:1050 nm … 1090 nm
• Absorptance : 25 %
• Modulation depth: 13 %
• Non-saturable loss: 12 %
• Saturation fluence: 300 μJ/cm2
• Damage threshold: 1.2 mJ/cm2
• Relaxation time constant: ~ 500 fs
• Chip area: 5.0 mm x 5.0 mm; other dimensions on request
• Chip thickness: 625 μm; semi-insulating GaAs

5. Part number STB-SA-1064-26-37ps-x at wavelength 1064 nm

• Laser wavelength: 1000 nm … 1100 nm
• Absorptance: 26 %
• Transmittance: 73 %
• Modulation depth: 4.9 %
• Saturation fluence: 300 μJ/cm2
• Damage threshold: 1 mJ/cm2
• Relaxation time constant: ~ 37 ps
• Chip area: 5.0 mm x 5.0 mm; other dimensions on request
• Chip thickness: 625 μm; semi-insulating GaAs

6. Part number STB-SA-1064-40-500fs-x at wavelength 1064 nm

• Laser wavelength: 1030 nm … 1090 nm
• Absorptance: 40 %
• Modulation depth: 25 %
• Non-saturable loss: 15 %
• Saturation fluence: 300 μJ/cm2
• Damage threshold: 1 mJ/cm2
• Relaxation time constant: ~ 500 fs
• Chip area: 5.0 mm x 5.0 mm; other dimensions on request
• Chip thickness: 625 μm; semi-insulating GaAs

7. Part number STB-SA-1340-22-20ps-x at wavelength 1340 nm

• Laser wavelength: 1340 nm
• Absorptance: 22 %
• Modulation depth: 14 %
• Non-saturable loss: 8 %
• Saturation fluence: 300 μJ/cm2
• Damage threshold: 1.2 mJ/cm2
• Relaxation time constant: ~ 20 ps
• Chip area: 5.0 mm x 5.0 mm; other dimensions on request
• Chip thickness: 625 μm; semi-insulating GaAs

8. Product list STB-SA, λ = 1550 nm, 625 µm substrate thickness for free space application

(1) Part number STB-SA-1550-6-20ps-x at wavelength 1550nm

• Laser wavelength: 1550 nm
• Absorptance : 6 %
• Modulation depth: 4 %
• Non-saturable loss: 2 %
• Saturation fluence: 300 μJ/cm2
• Damage threshold : 1.5 mJ/cm2
• Relaxation time constant: ~ 20 ps
• Chip area: 5.0 mm x 5.0 mm; other dimensions on request
• Chip thickness: 625 μm; semi-insulating GaAs

(2) Part number STB-SA-1550-35-2ps-x at wavelength 1550 nm

• Laser wavelength: 1400 nm … 1600 nm
• Absorptance: 35 %
• Modulation depth: 21 %
• Non-saturable loss: 14 %
• Saturation fluence: 300 μJ/cm2
• Damage threshold: 1.5 mJ/cm2
• Relaxation time constant: ~ 2 ps
• Chip area: 5.0 mm x 5.0 mm; other dimensions on request
• Chip thickness: 625 μm; semi-insulating GaAs

(3) Part number STB-SA-1550-46-2ps-x at wavelength 1550 nm

• Laser wavelength: 1400 nm … 1600 nm
• Absorptance: 46 %
• Modulation depth: 28 %
• Non-saturable loss: 18 %
• Saturation fluence: 300 μJ/cm2
• Damage threshold: 1.5 mJ/cm2
• Relaxation time constant: ~ 2 ps
• Chip area: 5.0 mm x 5.0 mm; other dimensions on request
• Chip thickness: 625 μm; semi-insulating GaAs

9. Product list STB-SA, λ = 1550 nm, 150 µm substrate thickness for fiber butt coupling

(1) Part number STB-SA-1550-25-2ps-x at wavelength 1550 nm

• Laser wavelength: 1500 nm … 1600 nm
• Absorptance: 25 %
• Modulation depth: 15 %
• Non-saturable loss: 10 %
• Saturation fluence: 300 μJ/cm2
• Damage threshold: 2 mJ/cm2
• Relaxation time constant: ~ 2 ps
• Chip area: 5.0 mm x 5.0 mm; other dimensions on request
• Chip thickness: 100 μm; semi-insulating GaAs

(2) Part number STB-SA-1550-41-2ps-thin-x at wavelength 1550 nm, thin saturable absorber for fiber coupling

• Laser wavelength: 1400 nm … 1600 nm
• Absorptance: 41 %
• Modulation depth: 25 %
• Non-saturable loss: 16 %
• Fiber coupling insertion loss: ≤ 1.6 dB
• Saturation fluence: 300 μJ/cm2
• Damage threshold: 1.5 mJ/cm2
• Relaxation time constant: ~ 2 ps
• Chip area: 1.3 mm x 1.3 mm; other dimensions on request
• Chip thickness: 150 μm; semi-insulating GaAs

(3) Part number STB-SA-1550-58-2ps-thin-x at wavelength 1550 nm, thin saturable absorber for fiber coupling

• Laser wavelength: 1400 nm … 1600 nm
• Absorptance: 58 %
• Modulation depth: 35%
• Non-saturable loss: 23 %
• Fiber coupling insertion loss: ≤ 1.6 dB
• Saturation fluence: 300 μJ/cm2
• Damage threshold: 1.5 mJ/cm2
• Relaxation time constant: ~ 2 ps
• Chip area: 1.3 mm x 1.3 mm; other dimensions on request
• Chip thickness: 150 μm; semi-insulating GaAs

10. Product list STB-SA, λ = 2000 nm

(1) Part number STB-SA-2000-1-x at wavelength 2000 nm

• Laser wavelength: 1900 nm … 2100 nm
• Absorptance: 1 %
• Modulation depth: 0.6 %
• Non-saturable loss: 0.4 %
• Saturation fluence: 300 μJ/cm2
• Damage threshold: 3 mJ/cm2
• Relaxation time constant: ~ 10 ps
• Chip area: 5.0 mm x 5.0 mm; other dimensions on request
• Chip thickness: 625 μm; semi-insulating GaAs

(2) Part number STB-SA-2000-25-10ps-x at wavelength 2000 nm

• Laser wavelength: 1800 nm … 2200 nm
• Absorptance: 25 % @ 2000 nm
• Transmittance: 74 % @ 2000 nm
• Reflectance: 1 % @ 2000 nm
• Modulation depth: 15 % @ 2000 nm
• Non-saturable loss: 11 % @ 2000 nm
• Saturation fluence: 2 mJ/cm2
• Damage threshold: 4 mJ/cm2
• Relaxation time constant: ~ 10 ps
• Chip area: 5.0 mm x 5.0 mm; other dimensions on request
• Chip thickness: 180 μm; semi-insulating GaAs

(3) Part number STB-SA-2000-43-x at wavelength 2000 nm

• Laser wavelength: 1800 nm … 2200 nm
• Absorptance: 43 % @ 2000 nm
• Transmittance: 56 % @ 2000 nm
• Reflectance: 0.2 % @ 2000 nm
• Modulation depth: 23 % @ 2000 nm
• Non-saturable loss: 20 % @ 2000 nm
• Saturation fluence: 300 μJ/cm2
• Damage threshold: 2 mJ/cm2
• Relaxation time constant: ~ 10 ps
• Chip area: 5.0 mm x 5.0 mm; other dimensions on request
• Chip thickness: 625 μm or 150 μm for fiber butt coupling ; semi-insulating GaAs

11. Part number STB-SA-2800-10-10ps-x at wavelength 2800 nm

• Laser wavelength: 2500 nm … 3000 nm
• Absorptance: 10 % @ 2.8 μm
• Transmittance: 90 % @ 2.8 μm
• Reflectance: 0 % @ 2.8 μm
• Modulation depth: 6 % @ 2.8 μm
• Non-saturable loss: 4 % @ 2.8 μm
• Saturation fluence: 300 μJ/cm2
• Damage threshold: 2 mJ/cm2
• Relaxation time constant: ~ 10 ps
• Chip area: 5 mm x 5 mm; other dimensions on request
• Chip thickness: 625 μm semi-insulating GaAs

RSA - Resonant Saturable Absorber in Transmission

The resonant saturable absorber can be used for passively mode-locking of a ring laser in a similar way as a SA. But it is a resonant device with the following special characteristics:

• Zero reflectance at the resonance wavelength for low intensity.
• Zero transmittance for all wavelengths outside the resonance.
• At the resonance wavelength increasing transmittance with increasing pulse fluence.
• The saturation fluence is substantial lower than that of a SA and even lower than that of a typical SAM.

The above mentioned characteristics allow the construction of a passively mode locked fiber ring laser with

• a laser wavelength fixed at the resonance wavelength of the RSA,
• and low power threshold for start of cw mode-locking.

RSA order information: Part-No description: STB-RSA-λ-A-T-τ-x

• λ - laser wavelength
• A - low intensity absorption
• T - low intensity transmission
• τ - absorber relaxation time
• x - mounting condition

Part number STB-RSA-1057-53-45-6ps-x at wavelength 1057 nm

• Resonance wavelength: 1056..1060 nm
• Absorptance: 53 %
• Transmittance: 45 %
• Reflectance: 2 %
• Modulation depth: △T = 27 %, △R = 15 %, △A = 43 %
• Saturation fluence: 25 μJ/cm2
• Damage threshold: 2 mJ/cm2
• Relaxation time constant: 6 ps
• Chip area: 5 mm x 5 mm; other dimensions on request
• Chip thickness: 450 μm; semi-insulating GaAs
• Front side protection: dielectric coating
• Back side coating: the SA back side is polished and antireflection coated for 1060 nm

Mounting option x denotes the type of mounting as follows:

• x = 5.0-0 unmounted chip 5.0 mm x 5.0 mm
• x = 5.0-12.7 g glued on a copper heat sink with 12.7 mm diameter with 4 mm hole
• x = 5.0-25.0 g glued on a copper heat sink with 25.4 mm diameter with 4 mm hole
• x = 5.0-25.4 g glued on a copper heat sink with 25.4 mm diameter with 4 mm hole