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 mirror | SAM | RSAM | SANOS | SOC | PCARSAM - Resonant Saturable Absorber Mirror> Contents● How does a RSAM work?● RSAM applications● Resonance wavelength● Bandwidth● Saturation intensity● Intensity dependent reflectance● Relaxation time> How does a RSAM work?The resonant saturable absorber mirror (RSAM) is a similardevice as a saturable absorber mirror (SAM), but has a largersaturable absorption, a smaller bandwidth and a lowersaturation fluence. The RSAM is designed as a resonantGires–Tournois interferometer with absorber layerspositioned at the antinodes of the optical field inside theresonator cavity.The RSAM is a nonlinear optical device, having a lowreflectance for week optical signals like noise and a highreflectance for high power signals like optical pulses. Opticalpulses saturate the absorber material inside the resonantcavity of the RSAM. Due to the short recovery time of theabsorber material the RSAM blocks immediately after thereflected pulse the optical noise floor.Important parameters of the RSAM are the●●●Resonance wavelengthBandwidthSaturation power density or the saturation fluence.> RSAM applicationsThe main applications for RSAMs are:● optical noise suppression, for example after an EDFA or a pulse picker (unsaturated RSAM reflectance = 0) -->SANOS (SAturable NOise Suppressor)● opto-optical wavelength conversion (unsaturated RSAM reflectance = 0)● passive mode-locking of fiber lasers (unsaturated RSAM reflectance > 0).> Resonance wavelengthInfluence of the angle of incidenceThe resonance wavelength λ of the Gires–Tournois interferometer depends on the angle of incidence ϕ and is given byeq.(1)withSeongKyeong Photonics 16 info@skphotonics.com
λ resonance wavelength of the interferometernrefractive index of the absorbing spacer layerd thickness of the absorbing spacer layerm order of the resonance; m = 1, 2, 3, ....ϕ angle of incidence on the RSAMIn case of a perpendicular beam incidence the first order resonance wavelength is simply λ = 2nd.Resonance wavelength λ of a RSAMwith λ(0) = 1064 nm and n = 3.1 after eq. (1)Resonance wavelength for parallel polarizedlight at different angles of incidenceSeongKyeong Photonics 17 info@skphotonics.com
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SAM – saturable absorber mirror

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