*Optoelectronic Key Elements for Polymeric Fiber Transmission Systems DOI: http://dx.doi.org/10.5772/intechopen.86423*

#### **Figure 9.**

*Transfer function of the four-channel demultiplexer with serial configuration and the channels centered at 404.9, 450.1, 529.1, and 646.4 nm.*


#### **Table 3.**

*Basic parameters of the four-channel demultiplexer with serial configuration.*

#### **Figure 10.**

*Principle of operation of a four-channel SI-POF demultiplexer with two-stage configuration (see enumeration in* **Figure 8***).*

### *Optical Fiber Applications*

incident spectrum into two spectral bands. The separation of the individual wavelength channels was then performed within the second stage of the demultiplexer. The corresponding laboratory setup is shown in **Figure 11**.

The practical realization was carried out with 505 nm cutoff long-pass dichroic mirror in the first stage of the demultiplexer. It reflected the lower spectral band so that 425 nm cutoff dichroic mirror was used in the second stage to demultiplex the signals for the output ports 1 and 2 in which 405 and 450 nm filters were employed, respectively. The upper spectral band transmitted by 505 nm mirror was demultiplexed in the second stage by 567 nm dichroic mirror. The filters centered at 525 and 650 nm were used in the output ports 3 and 4, respectively.

The corresponding transfer function is shown in **Figure 12**. The basic parameters of the demultiplexer are given in **Table 4**. The measurement results for the four-channel demultiplexer with two-stage configuration were presented at the International Conference on Plastic Optical Fibers (ICPOF) 2013 [26]. To comply with all other measurements shown in this chapter, which were performed 2 years thereafter, the demultiplexer setup was assembled and characterized

#### **Figure 12.**

*Transfer function of the four-channel demultiplexer with two-stage configuration and the channels centered at 404.9, 450.1, 528.3, and 646.4 nm [26].*

*Optoelectronic Key Elements for Polymeric Fiber Transmission Systems DOI: http://dx.doi.org/10.5772/intechopen.86423*


### **Table 4.**

*Basic parameters of the four-channel demultiplexer with two-stage configuration [26].*

again. While preserving the same principal behavior of the spectral response, the minimum IL in the output ports 1 to 4 was 6.15, 5.44, 4.21, and 3.85 dB, respectively. Those were by 0.49, 0.89, 0.74, and 0.66 dB higher values than those reported by Appelt et al. [26].
