|
Abstract:
Frequency-selective mm-wave photonic-crystal (PC) beam switches of increased sensitivity for rapid turning off and on quasi-optical beams in response to light pulses as control signals have been designed, manufactured and experimentally tested. Light-controllable PC-enhanced devices using semiconductor wafers (semi-insulating GaAs and Si layers or CdTe-coated quartz plates) with special surface patterning will provide additional functionality for mm-wave beam processing, with sensitivity improved, according to simulations, by 2 to 4 orders of magnitude as compared to a single-wafer device. Experimental testing of light sensitivity of different kinds of PC structures when using a flash lamp as a light source proved a possibility of making mmwave PC devices capable of switching quasi-optical beams with available inexpensive light sources. Quartz-air PCs with a Si wafer insertion have shown extreme sensitivity due to slow electron-hole recombination (tR50 s) and thick photoconductive layer in silicon (L=0.3mm) that allows one to completely turn off the transmission peak at f = 92.5 GHz by the light pulse of intensity I 0.4 W/cm2 (the PC transmission peak is reduced by 30 dB in response to the light whereas a single Si wafer transmission drops only by 4 dB). Similar kinds of PCs using CdTe-coated quartz wafer insertions, likewise GaAs wafers, are less sensitive to the light due to small recombination length (L 3 micro meters in CdTe and GaAs. Yet, a flash lamp illumination proved to be sufficient for observing a reduction of transmission peak of PC.
| Limitations: |
 APPROVED FOR PUBLIC RELEASE |
| Description: |
Final rept. 25 Aug 2010-25 Aug 2011 |
| Pages: |
32 |
| Report Date: |
Sep 2011 |
| Contract Number: |
FA8655-10-1-3086 |
| Report Number: |
A374055 |
|
|
|
|
|
Keywords relating to this report:
Email This Abstract
