Towards a FPGA-controlled deep phase modulation interferometer

M Terán,V Martín,O Gerberding,F Guzmán,T S Schwarze,G Heinzel,Ll Gesa,M Nofrarias,F Gibert,J Ramos-Castro,I Mateos,N Karnesis

doi:10.1088/1742-6596/610/1/012042

Abstract

Deep phase modulation interferometry was proposed as a method to enhance homodyne interferometers to work over many fringes. In this scheme, a sinusoidal phase modulation is applied in one arm while the demodulation takes place as a post-processing step. In this contribution we report on the development to implement this scheme in a fiber coupled interferometer controlled by means of a FPGA, which includes a LEON3 soft-core processor. The latter acts as a CPU and executes a custom made application to communicate with a host PC. In contrast to usual FPGA-based designs, this implementation allows a real-time fine tuning of the parameters involved in the setup, from the control to the post-processing parameters.

Highlights

Deep phase modulation interferometry [1] was proposed as a method to enhance homodyne interferometers to work over many fringes, allowing for instance continuous real-time tracking of a free falling test mass, as required for space based gravitational wave detectors [2]
The advantage of the proposed deep phase modulation scheme is that simplifies the required optical setup, driving and modulation electronics when compared with heterodyne based detection experiments [4]
The System On Chip approach While the original deep phase modulation interferometer was implemented in a scheme similar to the one shown in Fig. 1, recent developments have improved the design to shift the generation of signal modulation and the phase extraction to a FPGA [6]

Summary

Introduction

Deep phase modulation interferometry [1] was proposed as a method to enhance homodyne interferometers to work over many fringes, allowing for instance continuous real-time tracking of a free falling test mass, as required for space based gravitational wave detectors [2]. 1. Introduction Deep phase modulation interferometry [1] was proposed as a method to enhance homodyne interferometers to work over many fringes, allowing for instance continuous real-time tracking of a free falling test mass, as required for space based gravitational wave detectors [2]. The advantage of the proposed deep phase modulation scheme is that simplifies the required optical setup, driving and modulation electronics when compared with heterodyne based detection experiments [4].

Results

Conclusion