We propose and demonstrate an optical fiber probe which can simultaneously detect low and high-wavenumber coherent anti-Stokes Raman scattering (CARS) spectrum of samples. The low and high-wavenumber resonance signals are excited by the pump pulses and dual-Stokes pulses which are generated by the soliton self-frequency shift. The optical fiber taper probe focuses and delivers CARS excitation pulses to the samples. The detection of low and high-wavenumber regions can be achieved by the characterization of CN triple stretching vibrations and CH stretching vibrations. The simultaneous low and high-wavenumber optical fiber CARS probe will enable wider applications of quantitative chemical detection in in vivo biomedical research.
Microfluidic optomechanical device are a unique optofluidics platform that can exhibit optomechanical oscillation in the 10-20 MHz, driven by radiation pressure (RP). The resonant enhancement of both mechanical and optical response in microcavity optomechanical devices allows exquisitely sensitive measurements of environment stimuli (pressure, force, sound speed change) and non-solid states of matter (freely flowing particles, viscous fluids). In this work, we experimentally investigate temperature tuning of these hollow-shell oscillators. We also demonstrate the effect of temperature on the frequency domain of optical machine oscillation resonance shift and applied it to the field of temperature sensing. Our result is a step towards optomechanical sensor in the field of temperature.
The early diagnosis of myocardial infarction can significantly improve the survival rate in clinical medicine, therefore the high sensitivity detection of myocardial infarction biomarkers, such as creatine kinase (CK), lactate dehydrogenase (LDH) and cardiac troponin (cTn), is very important. In this work, a thin-wall microtubule whispering gallery modes (WGM) cavity biosensor to detect myocardial infarction marker has been achieved. The thin-wall microtubule WGM cavity is simply fabricated by tapering the silica capillary with oxyhydrogen flame. Using the self-polymerization effect of dopamine, the antibody is modified on the inner wall of the microtubule cavity to achieve specific capture of the cTnI-TnC complex protein. Moreover, by introducing the WGM microtubule cavity into the erbium-doped fiber laser cavity, the lasing wavelength can be utilized for the label-free detection of the myocardial infarction biomarker. The proposed microtubule cavity biosensor has advantages of inherent microfluidic channel, label-free detection and low detection limit, making itself a potential sensing platform in early diagnosis of heart disease.
We propose and demonstrate a coherent anti-Stokes Raman scattering (CARS) spectroscopic fiber probe based on a tapered optical fiber. The fiber probe prepared by the fiber heating fused and tapered method ensures that the output optical power density is high enough to excite the CARS signal. We have been able to detect Raman spectra of various chemical samples. The CARS fiber probe has the potential to achieve high spatial resolution. These results pave the way for flexibility and miniaturization of CARS probes
An optical fiber refractive index (RI) sensor based on open microcavity Mach-Zehnder interferometer (OMZI) and fiber ring laser (FRL) is proposed and demonstrated experimentally. The OMZI is manufactured by splicing a tiny single mode fiber (SMF) segment with multi-mode fiber (MMF) joints laterally. The large offset structure forms an open microcavity which can be filled with the liquid under test. Through inserting the OMZI into an erbium-doped FRL, the RI measurement can be achieved by discriminating the lasing wavelength, and the detection limit (DL) can be effectively improved owing to the laser sensing spectrum with narrower 3-dB bandwidth and higher optical signal-to-noise ratio (OSNR). Experimental results show that the output laser wavelength has a linear response to the RI change with a sensitivity of −2947.818 nm/RIU during the range of 1.33302~1.33402, and the DL is as low as 5.89×10−6 RIU. Compared with other optical fiber RI sensors, the proposed fiber laser RI sensor with an open microcavity has the advantages of small size, high sensitivity and low DL, making itself a competitive candidate for the microfluidic RI measurement in biochemistry.
We propose and demonstrate single optical fiber tweezers based on graded-index multimode fiber (MMF) which can adjust captured microparticles position in pendulum-style. The optical fiber tweezers can capture the yeast cell stably in three dimensions and swing the yeast cell 57.5 degrees around the fiber tip like a pendulum. The optical fiber tweezers are fabricated by asymmetrical fiber heating fused and tapered method. The capture and swing functions of the proposed optical fiber tweezers provide a new manipulation method for biomedical field.
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