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Tunable lasers handbook phần 10

Dao động tham số quang học có phát triển từ giai đoạn ban đầu của họ, nơi họ đã hơn một sự tò mò. Hiệu suất ban đầu được giới hạn bởi thiếu tinh thể cao chất lượng quang học phi tuyến. tinh thể phi tuyến với hệ số phi tuyến tương đối nhỏ. bơm laser hoạt động và hạn chế. Ngoài ra, tham số quang học | 434 Paul Zorabedian . -----------37------------7 . 1330.0 1325.0 1320.0 Equivalent Wavelength nm FIGURE 51 Swept-wavelengih measurements of AOTF transmittance characteristics a Crystal Technology filter driven at 88.5 MHz. b Matsushita filter driven at 68.54 MHz. Reproduced with permission from Zorabedian 461. 1995 IEEE. FIGURE 52 Grating-tuned extended-cavity laser containing a quasi-phase-matched KTP waveguide for intracavity frequency doubling. Reproduced with permission from Risk el ul. 162 and the American Institute of Physics. crystal can be placed inside an ECL to take advantage of the higher circulating intracavity power and the wavelength control provided by the tuning element. Intracavity second harmonic generation has been performed in grating ECLs using angle-phase-matched a-iodic acid 1110. bulk crystals 161 and quasiphase-matched periodically poled waveguides in KTP substrates 1621 Fig. 52 . Ten milliwatts of 532-nm light has been generated from a Nd YVO4 laser internally doubled with a KTP crystal and pumped with 55 mW from an interferencefilter-controlled quasi-degenerate ECL at 809 nm 1631 Fig. 53 . 8 Tunable External-Cavity Semiconductor Lasers 435 Collimating Focusing lens 1064 nm Laser diode lens FIGURE 53 Inlerference-filter-tuned extended-cavity laser used to pump intracavity-doubled Nd YVO4. Reproduced with permission from Kitaoka el at. 163 . 1 8.7 Injection Seeding The optical parametric oscillator OPO is arguably the most widely tunable coherent optical source. However it is difficult to obtain narrow-bandwidth output from an OPO. Use of dispersive elements in the OPO cavity complicates tuning. An alternative is to use a tunable ECL as an injection-seecing source. A 1.55-pm grating ECL with a 150-kHz linewidth has been used to seed a lithium niobate OPO 164 The OPO was pumped at 1.064 pm with a Nd YAG laser. Seeding reduced the bandwidth of the signal from 50 GHz without seeding to 0.18 GHz with seeding. Seeding was obtained for injected .