SRS Threshold Power
Calculate Stimulated Raman Scattering threshold for optical fibers.
Fiber Parameters
Raman Parameters
g_R at your pump wavelength: the threshold uses the value typed here. The pump wavelength only sets the Stokes wavelength and the hint below.
Typical Values (fused silica):
• gR ≈ 1×10⁻¹³ m/W for a 1 µm pump, scaling as 1/λp: 6.45e-14 m/W at 1550 nm
• Peak Raman shift ≈ 13.2 THz (≈ 113 nm at 1550 nm)
Results
P_th = 16·K·A_eff / (gR·L_eff): the CW pump power at which the forward Stokes wave grown from noise equals the transmitted pump (Smith 1972). In standard fibre pump and Stokes lose their relative polarization, so K = 2.
Threshold vs Fiber Length
Raman On-Off Gain vs Pump Power
Model and references
Textbook approximation. A standard approximation from the literature (for example paraxial, plane-wave or Gaussian-beam), valid within the range the page states. About the tiers
Smith critical power 16·K·A_eff/(g_R·L_eff) for forward SRS of a CW pump at the gain peak: K = 1 co-polarized, 2 standard fibre. Undepleted pump; on-off gain exp(g_R·P·L_eff/(K·A_eff)).
- Smith R. G. (1972). Optical power handling capacity of low loss optical fibers as determined by stimulated Raman and Brillouin scattering. Appl. Opt. 11, 2489. Critical powers 16 (SRS) and 21 (SBS). doi:10.1364/AO.11.002489
- Agrawal G. P. (2019). Nonlinear Fiber Optics, 6th ed., §8.1 (Raman gain g_R ∝ 1/λ_p, 13.2 THz shift, polarization). Academic Press. doi:10.1016/C2018-0-01168-8
- Stolen R. H., Ippen E. P. (1973). Raman gain in glass optical waveguides. Appl. Phys. Lett. 22, 276. doi:10.1063/1.1654637