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Recent Optical and Photonic Technologies 2012 Part 6

Tham khảo tài liệu 'recent optical and photonic technologies 2012 part 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 138 Recent Optical and Photonic Technologies X 65 X 6 mm wafer. The polarizations of the pump and THz waves were both parallel to the Z-axis of the crystals. The THz-wave output was measured with a fixed 4 K Si bolometer. 0.88 mJ 1250-1500 nm 532 nm 15 ns 50 Hz Half Wave Plate I I f 500 mm Mirror 5 mol MgO LiNbO3 Mirror I or beam dumper Beam Splitter with Si-prism coupler L 65 mm Mirror or beam dumper Tsurupica Lens f 45 mm THz wave a Fig. 13. Schematic of experimental setup for Cherenkov phase matching THz-wave generation with surfing configuration. 6.3 Results and discussions Input-output properties of THz-wave for pumping energy are shown in Fig.14 at 1.0 THz generation with a 2.49 degrees. Circles and triangles denotes THz-wave output signal with combined beams and with single beam by dumping the other beam before entrance to the crystal respectively. Maximum pumping energy of only 0.44 mJ was achieved at single beam pumping because a half of whole pumping energy was dumped as shown in Fig.13. The vertical axis is the THz-wave pulse energy calculated from the output voltage of a Si-bolometer detector a pulse energy of about 101 pJ pulse corresponded to a Si-bolometer voltage output of 1 V when the repetition rate was less than 200 Hz. As shown in the figure remarkable enhancement of THz-wave generation with surfing configuration whose magnetic was about 50 times was successfully observed. Inset of Fig.14 shows double logarithmic plot of input-output properties. Slope efficiency under combined beams and single beam pumping were almost same values. It means that enhancement factor of about 50 was a result of a suppression of phase miss-matching. The generated THz-waves at different position in the crystal were in-phase each other and outputted THz-wave was enhanced. Intensity of overlapping in-phase THz-waves in an absorptive media was calculated as shown in Fig.15. A 5 mol MgO-doped Lithium Niobate crystal at THz-wave frequency region would has about 30 cm-1 of