Electro-optic dual-comb interferometer for high-speed vibrometry

Abstract

Electro-optic frequency comb generators are particularly promising for dual-comb spectroscopy. They provide a high degree of mutual coherence between the combs without resorting to complex feedback stabilization mechanisms. In addition, electro-optic frequency combs can operate at very high repetition rates, thus providing very fast acquisition speeds. Here, we exploit these two features to resolve the rapid movement of a vibrating target. Our electro-optic dual-comb interferometer is capable of combining time-of-fight information with a more precise interferometric measurement based on the carrier phase. This fact, previously demonstrated by stabilized femtosecond frequency combs, allows us to increase the precision of the time-of-flight measurement by several orders of magnitude. As a proof of concept, we implement a fiber-based vibrometer that offers sub-nanometer precision at an effective acquisition speed of 250 kHz. These results expand the application landscape of electro-optic dual-comb spectroscopy to laser ranging and other remote sensing measurements.

Optimization of acousto-optic optical frequency combs

“…To conclude, an AO-OFC is an easily implementable and emerging technique for the generation of high quality broadband OFCs, which can find applications, beyond spectroscopy, in many cutting-edge areas of technology, such as distance ranging and fiber sensing [24][25][26][27]. Despite its relative simplicity, the present model is a valuable tool to optimize the comb performance, depending on the targeted application.…”

Dual-comb interferometry via repetition rate switching of a single frequency comb

“…Finally, to demonstrate the interferometric sensitivity of PHIRE, we perform a vibrometry measurement using the absolute phase φ 0 of the linear fit to extract acoustic information from the sub-wavelength motion of a distant vibrating surface. With an EOM comb, the minimum sensitivity of this type of measurement is limited on short time scales by the phase stability of the CW pump laser, but can readily achieve sub-nm levels [27].…”

Frequency-tuning dual-comb spectroscopy using silicon Mach-Zehnder modulators

“…Values of tens to hundreds of GHz are achieved for the microcombs [4,[6][7][16][17][24][25][26][27][33][34][35], while the repetition rate of fiber laser-based combs are on the orders of tens or hundreds of MHz [3][4][16][17][19][20][21][22]. On the contrary, using EOFCs the repetition rate is fully tunable within the modulator electro-optic bandwidth, up to tens of GHz [3][4][8][9][10][11][12]16,[28][29][30][31][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52].…”

“…While OFCs could be exploited by spatially demultiplexing the generated comb teeth, the most attractive use of these devices is the multi-heterodyne or dual-comb configuration, which enables high frequency resolution and accuracy, within a fast detection technique, with many applications in spectroscopy and metrology [16][17][18][19][20][21][22][23][25][26][27][28][29][30][31][36][37][45][46][47][54][55]. By combining two combs with slightly different repetition rates on a photodetector, an image of the optical spectrum can be obtained by measuring the RF spectrum.…”