Realization of fiber-based laser Doppler vibrometer with serrodyne frequency shifting

Abstract

We demonstrate a laser Doppler vibrometer (LDV) based on the serrodyne frequency shifting technique. A proof-of-principle system is implemented on the basis of fiber-optic components but opens the way toward an ultracompact integrated LDV system on a silicon chip. With a low laser power of 50 μW, the serrodyne LDV was able to measure submicrometer vibrations with frequencies in the audio range.

Fiber optic laser Doppler velocimeter with non-mechanical scanning of spatially encoded points for cross-sectional velocity distribution measurement

“…Single-point LDVs [13][14][15] and non-mechanical scanning LDV [16] using optical serrodyne modulation have been proposed to introduce the ability of directional discrimination. A LiNbO 3 (LN) phase shifter using the electro-optic effect is suitable to serrodyne modulation because it has wide bandwidth and does not require high-power signals.…”

Heterodyne laser Doppler vibrometers integrated on silicon-on-insulator based on serrodyne thermo-optic frequency shifters

“…However, because the piezoelectric effect is absent in unstrained crystalline silicon, it is difficult to generate an acoustic wave on SOI. To avoid this problem, we propose to use serrodyne modulation [7,8] for creating a frequency shift. Carrier injection/ depletion-based phase modulators [9] have a speed that is high enough to generate different serrodyne frequency shifts for commercial use.…”

“…In this paper, the frequency shift f ofs is kept at 2 kHz. Compared to our early work reported in [7], where we demonstrated a fiber-based implementation based on the same concept, this paper focuses on SOI-implementation and the devices on the SOIchip. The spurious reflections of these devices (e.g., optical splitters, grating couplers) are relatively strong, and they can cause an apparent influence in the LDV output.…”

Light collection from scattering media in a silicon photonics integrated circuit

“…In biological applications, one is often interested in collecting (back-)scattered light that has traveled through tissue to do e.g. Doppler velocimetry [1], Optical Coherence Tomography (OCT) [2] or Raman spectroscopy [3]. Efficient light collection is one of the key elements here.…”