The research examines the possibility of increasing of PPLN converters efficiency due to application of gradient nonlinear and optical environments.
For the analysis of structure gradient influence along PPLN on transformation efficiency of rating radiation on 1.
Radiation in PPLN and its absorption by a crystal matrix with coefficients of own absorption [[alpha].
Heat exchange is carried out with air at PPLN end face plane, and boundary conditions are: - K[nabla]T = h(T - [T.
Since the curve of a phase speeds mismatch in PPLN has not only temperature dependence, but also dependence on structure of a crystal which forms PPLN structure, due to dependence of n([lambda],T,[C.
In the capacity of lithium concentration change profiles in PPLN the following ones were chosen (Figure 2 (and)): 1-constant concentration of lithium along PPLN, a 2-parabolic lithium concentration increase profile with 49.
Figure 2 (b) presents that using of a falling-down parabolic of lithium concentration change profile along PPLN affects converter efficiency negatively.
The local warming up of PPLN along the direction of radiation distribution leads to change the conditions of interacting waves coordination of the main frequency (rating) and the second harmonica.
Transmittance of different components and overall detection efficiencies of the 1550 nm pump up-conversion detectors PPLN1 PPLN2 PC and WDM at 1310 nm 70% 74% Input coupling of PPLN at 1550 nm * 52% 71% Input coupling of PPLN at 1310 nm * 44% 59% Output coupling of PPLN at 710 nm * 92% 77% Filter before APD * 75% 88% APD efficiency at 710 nm * 70% 70% Overall efficiency 15% 20% *: These parameters are provided by the manufactures.
In previous work, the PPLN are pumped by continuous-wave (CW) light.
Second, the 1510 nm and 1590 nm light generate photons around 1310 nm via the anti-Stokes process and these non-linearly induced 13 10 nm photons will be up-converted to 710 nm in PPLN.
After polarization control is applied, the 1306 nm QKD signals and the 1557 nm pump are combined by the WDMs, sent to the PPLNs (HCP Photonics) where they are up-converted to 710 nm outputs and then further filtered and finally detected by the Si-APD (24).