SAM – saturable absorber mirror
SAM – saturable absorber mirror
SAM – saturable absorber mirror
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Refractive index > GaAs | AlAs | Al x Ga 1-x As | In x Ga 1-x As> Devices > Bragg <strong>mirror</strong> | <strong>SAM</strong> | R<strong>SAM</strong> | SANOS | SOC | PCASOC - Saturable Output Coupler> Contents● Aim of SOC● SOC parameters● Transmittance● Saturable absorption● Relaxation time● Reflectance bandwidth● Absorbance> Aim of SOCUsing a <strong>saturable</strong> output coupler (SOC), a selfstarting,passively mode-locked diode pumpedsolid-state laser with a very simple layout canbe arranged. A SOC is a combination of thewell known <strong>saturable</strong> <strong>absorber</strong> <strong>mirror</strong> (<strong>SAM</strong>)with an output coupler.In case of using a SOC instead of a <strong>SAM</strong> forpassive mode-locking the optical pump powercan be provided through the end <strong>mirror</strong> of thelaser cavity.Mode locking produces stable and coherentpulsed lasers by forcing the faces of themodes to maintain constant values relative toone another. These modes then combinecoherently. Fundamental mode-locking resultsin a train of optical pulses with a period of 2L/c, where L is the cavity length and c thespeed of the light in free space.Mode locking occurs when laser losses are modulated at a frequency equal to the reverse of the pulse periodc/2L. The SOC is a passive mode locking device without the use of an external drive signal, which spontaneouslylocks the modes with fast material response time.> SOC parametersA SOC consists of a Bragg-<strong>mirror</strong> on a semiconductor wafer like GaAs, covered by an <strong>absorber</strong> layer and a moreor less sophisticated top film system, determining the <strong>saturable</strong> loss. The back side of the SOC wafer isantireflection coated.The most important parameters of a SOC are:●●●●●transmittance<strong>saturable</strong> absorptionrelaxation timesaturation fluencereflectance bandwidth.> TransmittanceSeongKyeong Photonics 13 info@skphotonics.com