Differences
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| d2:offset_phase_lock_servo [2023/11/15 21:46] – Michael Radunsky | d2:offset_phase_lock_servo [2023/11/16 00:02] (current) – external edit 127.0.0.1 |
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| <imgcaption opls_schematic|Schematic of the D2-135 Offset Phase Lock Servo, D2-160 Beat Note Detector, and D2-150 Heterodyne Module>{{ :d2:d2-135:block_diagram.png?600|}}</imgcaption> | <imgcaption opls_schematic|Schematic of the D2-135 Offset Phase Lock Servo, D2-160 Beat Note Detector, and D2-150 Heterodyne Module>{{ :d2:d2-135:block_diagram.png?600|}}</imgcaption> |
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| A schematic of the OPLS, along with the [[d2:beat_note_detector|D2-160]] Beat Note Detector and [[d2:heterodyne_module|D2-150]] Heterodyne module is shown in <imgref opls_schematic>. The key component in the OPLS is a phase-frequency detector (PFD). The PFD compares the phase and frequency of the divided-by-N beat note to the reference frequency. The PFD outputs a signal proportional to the phase difference between the two input frequencies when there are no phase-slips between the two signals. This output provides a true phase-lock error signal. When there are phase slips, the PFD acts as a frequency comparator, aiding initial lock-up and enabling the OPLS to function as a //frequency//// ////offset//// ////lock// for laser sources with significant phase noise such as DFB and DBR laser diodes. The output of the PFD is fed to a charge pump and finally to the loop filter, where it is then fed back to the slave laser to control the frequency of the beat note. | A schematic of the OPLS, along with the [[d2:beat_note_detector|D2-160]] Beat Note Detector and [[d2:heterodyne_module|D2-150]] Heterodyne module is shown in <imgref opls_schematic>. The key component in the OPLS is a phase-frequency detector (PFD). The PFD compares the phase and frequency of the divided-by-N beat note to the reference frequency. The PFD outputs a signal proportional to the phase difference between the two input frequencies when there are no phase-slips between the two signals. This output provides a true phase-lock error signal. When there are phase slips, the PFD acts as a frequency comparator, aiding initial lock-up and enabling the OPLS to function as a //frequency//// ////offset//// ////lock// for laser sources with significant phase noise. The output of the PFD is fed to a charge pump and finally to the loop filter, where it is then fed back to the slave laser to control the frequency of the beat note. |
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| The loop filter has user-adjustable proportional-integral-differential (PID) feedback and an additional high-frequency roll-off frequency. Tuning the values of the PID loop filter allows the user to optimize the feedback to the laser for best offset locks. This is further discussed below. | The loop filter has user-adjustable proportional-integral-differential (PID) feedback and an additional high-frequency roll-off frequency. Tuning the values of the PID loop filter allows the user to optimize the feedback to the laser for best offset locks. This is further discussed below. |
