FPGA-based frequency estimation of a DFB laser using Rb spectroscopy for space missions

Spindeldreier, Christian; Wendrich, Thijs; Rasel, Ernst M.; Ertmer, W.; Blume, Holger

doi:10.1109/asap.2016.7760795

Cited by 1 publication

(4 citation statements)

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“…A pattern matching algorithm using the mean scan current to preselect the part of the spectrum is used to find the position of the scan. 14 The estimated position represents the mean wavelength of the processed scan signal. This information is used within a PI controller which controls the mean value of the scan current, closing the wavelength control loop.…”

Section: Wavelength Estimation and Stabilization Principlementioning

confidence: 99%

“…After storing the scan signal to its RAM block, the wavelength estimator determines the position of the present scan in the reference spectrum using a scalable hardware module which realizes the sum-of-absolute-differences (SAD) pattern matching algorithm. The internal architecture including all details is described by Spindeldreier et al 14 The estimated position is used as the process value for the PI-controller while the position derived from the user defined target wavelength is the setpoint. The control value is the mean current of the triangle wave.…”

Section: Laser Frequency Stabilization Hardware Modulementioning

confidence: 99%

“…As the number of parallel SAD cores inside the wavelength estimation module is variable, but influences the system performance, 14 the number was set to 300 cores which is slightly more than half the maximum number for all further evaluations. The whole system is clocked with 50 MHz, while the critical path is within the LEON3 processor.…”

Section: Timing Of the Control Loopmentioning

confidence: 99%

“…Transferring the algorithm to an FPGA reduces communication latency and paves the way to use the estimation algorithm for real time wavelength stabilization and controlling. 14 This paper presents a complete wavelength stabilization system based on a wavelength estimation module. The signal processing chain consists of spectroscopy input signal generation, demodulation, wavelength estimation and controlling.…”

Section: Introductionmentioning

confidence: 99%

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FPGA based laser frequency stabilization using FM spectroscopy

Spindeldreier

Bartosch

Wendrich

et al. 2018

Laser Resonators, Microresonators, and Beam Control XX

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Frequency stabilized light sources with narrow linewidth are mandatory for atom interferometry based experiments. For compact experiment designs used on space platforms, tunable DFB diode lasers are often used. These lasers combine low energy consumption with small sizes, but lack long-term frequency stability. This paper presents an FPGA based laser frequency stabilization system for highly variable target frequencies using frequency modulated Rb-spectroscopy achieving latencies below 100 µs. The system consists of a DFB laser, a Rb-spectroscopy cell, a laser current controller and an FPGA board with an analog-digital conversion board. The digital part of the frequency stabilization system is a SoC mapped on an FPGA. The SoC consists of a processor, enabling user interaction via network connection, and the dedicated frequency stabilization module. This module consists of a demodulation stage, digital filters, a frequency estimator and a controller. To estimate the frequency, small ramps of the laser frequency are generated using a high-speed DAC connected to the laser current controller. The absorption spectroscopy output of this beam is sampled using a photodiode and a high-speed ADC. After signal conditioning with digital filters, the frequency estimator extracts the present mid-frequency of the laser applying pattern matching with a prerecorded reference spectrum. The frequency controller adjusts the mean laser current based on this estimation. The performance as well as the accuracy of the proposed laser stabilization system and its FPGA resource and power consumption are evaluated.

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Section: Wavelength Estimation and Stabilization Principlementioning

confidence: 99%

Section: Laser Frequency Stabilization Hardware Modulementioning

confidence: 99%

Section: Timing Of the Control Loopmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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