Berlin 2014 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 68: Precision measurements and metrology V

Q 68.3: Talk

Friday, March 21, 2014, 17:15–17:30, DO24 1.101

High-precision phasemeter for the Deep Phase Modulation Interferometry — •Thomas S. Schwarze — Albert-Einstein-Institut Hannover

We present our results of the development of a dedicated-hardware modulation signal synthesis and phasemeter system for the Deep Modulation Interferometry technique. For this technique, a sinusoidal modulation is applied through a ring piezo-electric actuator to one arm of a Mach-Zehnder interferometer in order to reach large modulation depths in the order of 10 rad. The interferometer phase is extracted by a complex fit to the harmonic amplitudes of the modulation frequency. The presented system prototype uses a Direct Digital Synthesizer and a Digital Signal Processing core, both implemented on a Field Programmable Gate Array. The first allows generation and control of the modulation signal to drive the ring piezo-electric actuator. The latter computes the harmonic amplitudes by performing multiple single-bin discrete Fourier transforms. These amplitudes are subsequently transmitted to a PC via Ethernet to conduct the complex fit computations. The results obtained from a zero measurement with an optical signal revealed a phasemeter precision of 2.3 pm/rtHz below and 0.1 pm/rtHz above 10 Hz.