## 3 Results
### The Performance of Liquid Crystal Optical Power Limiter with Integrated Thin-Film Polarizers  
In further developing our optical power limiter that employs both pure and dye-doped NLC, we have optimized the device's functionality by directly incorporating plastic polarizers with the twisted nematic NLC cell. This modification has streamlined the device's overall structure, obviating the need for external polarizers. Plastic polarizers were selected due to their thermal conductivity, which is essential to the device's performance. We have already demonstrated that dye-doped NLC can effectively lower the polarization switching threshold and enhance optical limiting by modulating the order parameter through laser-induced heating. As previously stated, the heating causes a reduction in birefringence, which nearly disappears with high laser exposure. This inhibits the polarization rotation process and decreases transmission. The key benefit of using plastic polarizers is their ability to cause a faster and more significant temperature change within the NLC layer. This change directly influences the liquid crystals' refractive properties by further reducing birefringence in response to optical intensity. Consequently, the threshold power required for effective optical limiting is substantially lowered, making the device more efficient and responsive in practical applications. A polarizer that absorbs light and has varying thermal conductivities and damage thresholds may be chosen to optimize the trade-off between switching power and/or switching time, depending on the application's specific requirements. The TN NLC cells with two internal, crossed plastic film polarizers were prepared, and their transmission characteristics were checked for 12 \(\upmu\)m and 30 \(\upmu\)m thick cells in pure 6 CHBT NLC and 6 CHBT doped with 1% \(w\)/\(w\) of SBII dye. The experimental results are summarized in Figure 3. For the pure 6 CHBT NLC (Figure 3a), we observed that the threshold power for the 12 \(\upmu\)m and 30 \(\upmu\)m TN cells was significantly lower than for typical glass cells, as the transmission characteristics dropped rapidly at powers of about 155 mW and 80 mW, respectively. For the doped NLC with an increased value of linear absorption (Figure 3b), we observed a further reduction in the threshold power, depending on the cell thickness. The NLC optical power limiter activated at 80 mW and 40 mW, which was observed for the cells with a thickness of 12 \(\upmu\)m (black circles) and 30 \(\upmu\)m (brown squares). The absorbent dopant, combined with additional cell insulation in the form of plastic polarizers, significantly reduced the threshold power. However, this came at the expense of increased attenuation of the optical power limiter in the power range below the activation value. Compared to pure NLC, the transmission of dye-doped NLC cells with foil film polarizers was reduced by approximately 25% for the 12 \(\upmu\)m cell and about 40% for the 30 \(\upmu\)m cell. However, software compensation could offset the lower transmission level after adequately configuring the final NLC optical limiter device. The experimental results for the performance of the investigated NLC optical power limiters with foil polarizers at different ambient temperatures were determined for cells of a thickness of 12 \(\upmu\)m and 30 \(\upmu\)m. The transmission characteristics are illustrated in Figures 3c and 3d, respectively.