Fengguo Sun

A New Fiber-Bragg-Grating Sensor Interrogation System Deploying Free-Spectral-Range-Matching Scheme With High Precision and Fast Detection Rate

A new method for fiber-Bragg-grating sensor interrogation and multiplexing is proposed and its operating features are investigated experimentally. This technique utilizes free-spectral-range-matched interrogation (FSRMI) employing a tunable scanning Fabry-Perot filter and a multichannel bandpass filter. An -channel FSRMI allows simultaneous scanning and thus improvement of detection speed by times compared to a nonfree-spectral-range-matched interrogation scheme. A 5-pm wavelength resolution has been obtained. This technique simultaneously scans the multiple transmission peaks and provides solutions to a wavelength-modulated distributed sensors and multisensor arrays with high sampling speed and wavelength accuracy.

Self-Referencing in Optical-Fiber Surface Plasmon Resonance Sensors

We have achieved a self-referencing function in optical-fiber surface plasmon resonance (SPR) sensors by fabricating two tandem SPR sections in a single optical fiber and by coating one of the sections with a reference material to create an additional resonance at a longer wavelength for referencing, while keeping the other one for regular sensing. By choosing a reference material with a very large thermooptic coefficient, we have demonstrated an SPR optical fiber sensor that can, by itself, correct the effect of temperature variation in the testing medium.

A tunable multiwavelength fiber ring laser for measuring polarization-mode dispersion in optical fibers

We describe and demonstrate a tunable triple-wavelength erbium-doped fiber ring laser along with a method of measuring polarization-mode dispersion (PMD) in optical fibers based on a broad-band orthogonal-pump four-wave mixing in a semiconductor optical amplifier. The measured PMD results for optical fibers are in good agreement with values measured by means of commercial PMD testing equipment.

Arrayed-waveguide-grating-based interrogator for wavelength-modulated multi-fiber-optic sensor applications

Simultaneous interrogation of six distributed wavelength modulated fiber-optic sensors has been demonstrated using an arrayed-waveguide-grating-based interrogation technique proposed by our laboratory. This letter analyzes the operating principle of the method and reports the experimental results of this application. The results show that the interrogator proposed offers better than 1-pm wavelength resolution and has the potential of being packaged into a hand-held rugged device.

Miniaturized Optical Fiber Sensor Interrogation System Employing Echelle Diffractive Gratings Demultiplexer for Potential Aerospace Applications

To enable the application of optical fiber sensors to aerospace vehicles, the sensor interrogation or data acquisition system has to meet small size and low weight requirements. This paper presents the developmental work of an echelle diffractive gratings (EDGs) demultiplexer-based optical fiber sensor interrogation system. The operation principle of this system and its application to fiber Bragg grating (FBG) sensor interrogation are presented. The experimental results have shown that the developed interrogator (not including the electronic controller) weighs less than 60 g and provides better than 1 pm measurement resolution and better than plusmn10 pm measurement accuracy.

High-power multiwavelength Er/sup 3+/-Yb/sup 3+/ codoped double-cladding fiber ring laser

A high-power simultaneous multiwavelength lasing in an Er/sup 3+/-Yb/sup 3+/ codoped double-cladding fiber (EYCDF) ring laser is demonstrated based on a wavelength-dependent filter through spatial mode beating within the multimode fiber section. We have investigated the relationship between the lasing wavelengths and the length of the EYCDFs. The experimental results indicate that both the number of lasing wavelength lines and the spacing between two adjacent lasing lines can be controlled by the changes of the lasing light polarization states.

Ultra-broadband quantum-dot semiconductor optical amplifier and its applications

We have developed an ultra-broadband InAs/InGaAsP quantum-dot semiconductor optical amplifier around 1520 nm with the 3-dB bandwidth of 150 nm. The four-wave mixing process and multi-wavelength lasers have been demonstrated by using our QD-SOAs.

Heat Control of an Integrated Silica VMUX Using Constant Working Power

An on-chip integrated silica variable multiplexer (VMUX) cannot be practically packaged as the involved variable optical attenuator (VOA) is associated with a large amount of heat change and the involved arrayed waveguide grating (AWG) is sensitive to temperature change. On the basis of our success in substantially reducing VOAs power consumption, we have introduced an idle heater for each VOA channel to balance its attenuation-associated heat change and keep the whole arrayed VOA under constant working power. Consequently, a 40-channel AWG-VOA integrated VMUX can be easily stabilized at an optimum setting temperature by simply dissipating the same amount of heat with a conventional packaging. Simulations have shown that both the involved AWG and the VOA work properly in the VMUX device

Piezoelectric bimorph optical-fiber sensor.

We propose and demonstrate a novel high-voltage optical-fiber sensor. This sensor consists of an emitting fiber, a receiving fiber, and a piezoelectric bimorph transducer. The emitting fiber is fixed in a base, whereas the receiving fiber is mounted on the free end of the piezoelectric bimorph transducer. When a voltage is applied to the piezoelectric bimorph transducer, its free end is displaced over a distance delta. The displacement induces a loss in the optical coupling between the emitting and the receiving fiber. The voltage can be measured by monitoring the coupling loss.

Optimal position of nonlinear regenerators in optical communication links

We propose a general method of determining the optimal position of nonlinear regenerators and the bit-error-rate (BER) improvement in optical communication links. We calculate the BER improvement as a function of the position of the regenerator and the optical link noise parameter using an ideal regenerator as an example.