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Tham khảo tài liệu 'advances in solid-state lasers: development and applicationsduration and in the end limits part 9', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 312 Advances in Solid-State Lasers Development and Applications beam splitter mirror A . One is focused onto the first MgO PPLN crystal for f0 control the other part is focused onto the second MgO PPLN crystal for an independent out-of-loop phase noise measurement. Though the SNR of f0 for each part is about 35dB 100kHz resolution bandwidth which is lower because the input power of each beam decreases to only one half than before it is still sufficient for control and phase noise measurement. The in- and out-of-loop single-side-band SSB phase-noise power spectral densities PSD of f0 are obtained by injecting these signals into a signal analyzer. The measured SSB phase-noise PSD of f0 and the noise floor of analyzer are shown in Fig. 12 respectively. The phase error integrated from 1Hz to 100kHz is about 230mrad for in-loop and 242 mrad for out-of-loop. There is a typical 12 mrad increase from in-loop accumulated phase noise to out-of-loop. On the contrary in the conventional f-to-2f scheme where a piece of PCF is used for octavespanning spectrum generation the phase noise for out-of-loop is usually increased by several times compared with that for in-loop. As reported in Ref. 50 the accumulated phase noise is 0.1 rad for in-loop and more than 0.2 rad for out-of-loop 1Hz 100kHz corresponding to an approximate two-fold increase. This significant difference originates from the conversion of amplitude fluctuations to phase fluctuations in PCF. Based on the monolithic scheme however there is no additional noise introduced by PCF and then the difference between in- and out-of-loop is steeply decreased. Obsevation Time s Fourier Frequency Hz Fig. 12. Bottom-Left the SSB noise power spectrum of f0 as the function of Fourier frequency. Black line in-loop phase error. Red line out-of -loop phase error. Blue line the noise floor of the signal analyzer. Top-Right the accumulated phase noise of in-loop black closed square and out-of-loop red closed square as the function of .
