Jiang Junfeng

The Turning Error Effect of Reflectors in the Talbot Interferometer used for Writing Fiber Bragg Grating

The Talbot interferometer used for writing fiber Bragg grating (FBG) is analyzed effectively in this paper. Based on electromagnetic theory, a computing model of the Talbot interferometer is established with the temporal and the spatial coherence taken into account and with the turning angle of the reflectors as a critical parameter. The model can provide a more detailed and precise information about the interference field and is used to study the effect of the turning error of the reflectors in writing FBG. The calculation result shows that the turning error has an important effect on the visibility of the far interference field.

Temporal overlap estimation based on interference spectrum in CARS microscopy

Coherent Anti-Stokes Raman Scattering (CARS) microscopy has attracted lots of attention because of the advantages, such as noninvasive, label-free, chemical specificity, intrinsic three-dimension spatial resolution and so on. However, the temporal overlap of pump and Stokes has not been solved owing to the ultrafast optical pulse used in CARS microscopy. We combine interference spectrum of residual pump in Stokes path and nonlinear Schrodinger equation (NLSE) to realize the temporal overlap of pump pulse and Stokes pulse. At first, based on the interference spectrum of pump pulse and residual pump in Stokes path, the optical delay is defined when optical path difference between pump path and Stokes path is zero. Then the relative optical delay between Stokes pulse and residual pump in PCF can be calculated by NLSE. According to the spectrum interference and NLSE, temporal overlap of pump pulse and Stokes pulse will be realized easily and the imaging speed will be improved in CARS microscopy.Coherent Anti-Stokes Raman Scattering (CARS) microscopy has attracted lots of attention because of the advantages, such as noninvasive, label-free, chemical specificity, intrinsic three-dimension spatial resolution and so on. However, the temporal overlap of pump and Stokes has not been solved owing to the ultrafast optical pulse used in CARS microscopy. We combine interference spectrum of residual pump in Stokes path and nonlinear Schrodinger equation (NLSE) to realize the temporal overlap of pump pulse and Stokes pulse. At first, based on the interference spectrum of pump pulse and residual pump in Stokes path, the optical delay is defined when optical path difference between pump path and Stokes path is zero. Then the relative optical delay between Stokes pulse and residual pump in PCF can be calculated by NLSE. According to the spectrum interference and NLSE, temporal overlap of pump pulse and Stokes pulse will be realized easily and the imaging speed will be improved in CARS microscopy.

Intravascular Frequency-domain optical coherence tomography imaging system

We present a Frequency-domain optical coherence tomography (FD-OCT) system for intravascular imaging. The whole system consists of 4 parts: imaging catheter (IC), motion controller (MC), optical engine (OE) and data acquisition and processing module (DAPM). By using swept laser source with 50 KHz sweep speed and high speed optical rotary jiont, we can get 100 frames per second (fps) and scan 20 mm vessel per second.

Selective excitation of whispering gallery modes by a fiber taper

Coupling from tapered fibers into the whispering gallery modes of the optofluidic ring resonator is investigated analytically. By adjusting the taper diameter to match the propagation constant of the mode in the taper with that of the resonant mode of interest, the mode with the best sensing capability can be excited selectively and efficiently.