skip to main content

Title: Picostrain-resolution fiber-optic sensing down to sub-10  mHz infrasonic frequencies

High-resolution strain sensing based on long, high-finesse fiber Fabry–Perot interferometers (FFPIs) has been demonstrated with a special focus on the infrasonic frequency range. A novel dual-FFPI scheme allows the large environment-induced background at low frequencies to be suppressed, permitting high strain resolution limited only by excess electronic noise. Noise-equivalent strain resolution of257pε<#comment/>/√<#comment/>Hzhas been achieved at 6 mHz, and the resolution improves to∼<#comment/>200fε<#comment/>/√<#comment/>Hzbetween 4–20 Hz. Without the use of any additional optical frequency references and with only off-the shelf commercial components, these resolutions are much better than most in the prior reports. Especially, an improvement of a factor of 1.8 is achieved in comparison with the highest resolution reported so far near 5 Hz. The limiting factors of the current scheme have been analyzed in detail, and the application prospects have been demonstrated using an acoustic transducer. The work lays out the potential of using long FFPIs with high finesse for high-resolution fiber-optic sensing in the infrasonic frequency range.

more » « less
Author(s) / Creator(s):
Publisher / Repository:
Optical Society of America
Date Published:
Journal Name:
Journal of the Optical Society of America B
0740-3224; JOBPDE
Page Range / eLocation ID:
Article No. 2773
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. The mid-IR spectroscopic properties ofEr3+doped low-phononCsCdCl3andCsPbCl3crystals grown by the Bridgman technique have been investigated. Using optical excitations at∼<#comment/>800nmand∼<#comment/>660nm, both crystals exhibited IR emissions at∼<#comment/>1.55,∼<#comment/>2.75,∼<#comment/>3.5, and∼<#comment/>4.5µ<#comment/>mat room temperature. The mid-IR emission at 4.5 µm, originating from the4I9/2→<#comment/>4I11/2transition, showed a long emission lifetime of∼<#comment/>11.6msforEr3+dopedCsCdCl3, whereasEr3+dopedCsPbCl3exhibited a shorter lifetime of∼<#comment/>1.8ms. The measured emission lifetimes of the4I9/2state were nearly independent of the temperature, indicating a negligibly small nonradiative decay rate through multiphonon relaxation, as predicted by the energy-gap law for low-maximum-phonon energy hosts. The room temperature stimulated emission cross sections for the4I9/2→<#comment/>4I11/2transition inEr3+dopedCsCdCl3andCsPbCl3were determined to be∼<#comment/>0.14×<#comment/>10−<#comment/>20cm2and∼<#comment/>0.41×<#comment/>10−<#comment/>20cm2, respectively. The results of Judd–Ofelt analysis are presented and discussed.

    more » « less
  2. Capable of imaging blood perfusion, oxygenation, and flow simultaneously at the microscopic level, multi-parametric photoacoustic microscopy (PAM) has quickly emerged as a powerful tool for studying hemodynamic and metabolic changes due to physiological stimulations or pathological processes. However, the low scanning speed poised by the correlation-based blood flow measurement impedes its application in studying rapid microvascular responses. To address this challenge, we have developed a new, to the best of our knowledge, multi-parametric PAM system. By extending the optical scanning range with a cylindrically focused ultrasonic transducer (focal zone,76µ<#comment/>m×<#comment/>4.5mm) for simultaneous acquisition of 500 B-scans, the new system is 112 times faster than our previous multi-parametric system that uses a spherically focused transducer (focal diameter, 40 µm) and enables high-resolution imaging of blood perfusion, oxygenation, and flow over an area of4.5×<#comment/>1mm2at a frame rate of 1 Hz. We have demonstrated the feasibility of this system in the living mouse ear. Further development of this system into reflection mode will enable real-time cortex-wide imaging of hemodynamics and metabolism in the mouse brain.

    more » « less
  3. One of the major challenges in large scale optical imaging of neuronal activity is to simultaneously achieve sufficient temporal and spatial resolution across a large volume. Here, we introduce sparse decomposition light-field microscopy (SDLFM), a computational imaging technique based on light-field microscopy (LFM) that takes algorithmic advantage of the high temporal resolution of LFM and the inherent temporal sparsity of spikes to improve effective spatial resolution and signal-to-noise ratios (SNRs). With increased effective spatial resolution and SNRs, neuronal activity at the single-cell level can be recovered over a large volume. We demonstrate the single-cell imaging capability of SDLFM within vivoimaging of neuronal activity of whole brains of larval zebrafish with estimated lateral and axial resolutions of∼<#comment/>3.5µ<#comment/>mand∼<#comment/>7.4µ<#comment/>m, respectively, acquired at volumetric imaging rates up to 50 Hz. We also show that SDLFM increases the quality of neural imaging in adult fruit flies.

    more » « less
  4. Materials with strong second-order (χ<#comment/>(2)) optical nonlinearity, especially lithium niobate, play a critical role in building optical parametric oscillators (OPOs). However, chip-scale integration of low-lossχ<#comment/>(2)materials remains challenging and limits the threshold power of on-chipχ<#comment/>(2)OPO. Here we report an on-chip lithium niobate optical parametric oscillator at the telecom wavelengths using a quasi-phase-matched, high-quality microring resonator, whose threshold power (∼<#comment/>30µ<#comment/>W) is 400 times lower than that in previousχ<#comment/>(2)integrated photonics platforms. An on-chip power conversion efficiency of 11% is obtained from pump to signal and idler fields at a pump power of 93 µW. The OPO wavelength tuning is achieved by varying the pump frequency and chip temperature. With the lowest power threshold among all on-chip OPOs demonstrated so far, as well as advantages including high conversion efficiency, flexibility in quasi-phase-matching, and device scalability, the thin-film lithium niobate OPO opens new opportunities for chip-based tunable classical and quantum light sources and provides a potential platform for realizing photonic neural networks.

    more » « less
  5. The ambition of this review is to provide an up-to-date synopsis of the state of 3D printing technology for optical and photonic components, to gauge technological advances, and to discuss future opportunities. While a range of approaches have been developed and some have been commercialized, no single approach can yet simultaneously achieve small detail and low roughness at large print volumes and speed using multiple materials. Instead, each approach occupies a niche where the components/structures that can be created fit within a relatively narrow range of geometries with limited material choices. For instance, the common Fused Deposition Modeling (FDM) approach is capable of large print volumes at relatively high speeds but lacks the resolution needed for small detail (><#comment/>100µ<#comment/>m) with low roughness (><#comment/>9µ<#comment/>m). At the other end of the spectrum, two-photon polymerization can achieve roughness (<<#comment/>15nm) and detail (<<#comment/>140nm) comparable to commercial molded and polished optics. However, the practical achievable print volume and speed are orders of magnitude smaller and slower than the FDM approach. Herein, we discuss the current state-of-the-art 3D printing approaches, noting the capability of each approach and prognosticate on future innovations that could close the gaps in performance.

    more » « less