Zhenan Jia

Humidity Sensor Based on Hybrid Fiber Bragg Grating/Abrupt Fiber Taper

A novel fiber humidity sensor based on fiber Bragg grating (FBG) cascaded with an abrupt fiber taper is proposed and demonstrated. The evanescent wave around the abrupt fiber taper varies with humidity around the sensor, so that the power of the FBG core reflection is affected by the ambient humidity. Experimental results show that the sensor has a linear response to humidity with sensitivity of 0.10-dB/%RH in the humidity range of 50%–90% RH. Such a cost-effective, compact, and reflection power detection-based humidity sensor could be a good candidate in applications.

Humidity sensing of microfiber Bragg grating

A humidity sensor based on microfiber Bragg grating is proposed and demonstrated. The microfiber Bragg grating is obtained through chemical etching commercial fiber Bragg grating. The experimental results show that the central wavelength of the microfiber Bragg grating has red shift with humidity increasing, while the power decreases. The relative humidity sensitivity of the microfiber Bragg grating with diameter of 8.9um is 3pm/%RH in the range of 55%-80%RH. Furthermore, the sensor has a linear response to humidity with linear fitting of 0.991. The sensor possesses advantages of easy fabrication and low cost.

Superfluorescent fiber source achieving multisignal power equalization in distributed fiber Bragg grating sensing

In order to achieve multisignal power equalization in a quasidistributed fiber Bragg grating (FBG) sensing system, an erbium-doped fiber (EDF) superfluorescent source with high flatness and broadband spectrum is presented using a three-stage double-pump configuration. The spectral protrusions in the vicinity of 1532 and 1570 nm are flattened, which is achieved by designing a gain flattening filter with a long-period grating. The result shows that the flatness of the output spectrum covering the C and L band, from 1526.52 to 1607.87 nm, is less than 0.76 dBm. The 3 dB bandwidth is 75.68 nm, and the output power of 13.11 mW is achieved in the C and L band. By using the fiber amplified spontaneous emission (ASE) source in FBG sensing system for decreasing multisignals peak power variation, the standard deviation of multisignals peak power is decreased to 1.00 dBm. In a multiplexed FBG sensing system, the high flattening fiber ASE source is beneficial to long-distance transmission, amplification, recognition, and demodulation of FBG sensing signals.

Research and analysis on the broadband dispersion tailoring of the sub-micro silicon-on-insulator waveguides

High-order dispersions of the silicon-on-insulator (SOI) waveguides with different shapes (including slab, ridge and slot) have been obtained and compared using the finite element method (FEM). Through adjusting the geometrical parameters of the waveguides, single or dual zero-dispersion wavelengths (ZDWs) can be tuned in the broadband wavelength range. Differences of dispersion curves among these waveguides are analyzed from the viewpoint of structure and mechanism in detail. It is remarkably shown the number of ZDWs can be varied from 0 to 2 and the position of the ZDWs can be tuned from 1400 nm to 1900 nm flexibly. Moreover, the differences of dispersion features in short and long wavelength regions are also discussed deeply. Due to the dispersion of SOI waveguides playing a dominated role in many nonlinear optical effects, this research can make some contribution for dispersion tailoring and nonlinear optics.

S-band gain-flattened EDFA with two-stage double-pass configuration

A gain-flattened S-band erbium-doped fiber amplifier (EDFA) using standard erbium-doped fiber (EDF) is proposed and experimentally demonstrated. The proposed amplifier with two-stage double-pass configuration employs two C-band suppressing filters to obtain the optical gain in S-band. The amplifier provides a maximum signal gain of 41.6 dB at 1524 nm with the corresponding noise figure of 3.8 dB. Furthermore, with a well-designed short-pass filter as a gain flattening filter (GFF), we are able to develop the S-band EDFA with a flattened gain of more than 20 dB in 1504-1524 nm. In the experiment, the two-stage double-pass amplifier configuration improves performance of gain and noise figure compared with the configuration of single-stage double-pass S-band EDFA.