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This study proposes a new type of fused cone Sagnac ring humidity sensor based on graphene properties. First, the single-mode optical fiber (SMF) is fused with the photonic crystal fiber (PCF) to form SMF-PCF-SMF interference. Then, the SMFs at both ends of the PCF are folded in half to form a ring. The ring is placed on the fiber pulling cone translation platform for pulling cone coupling. A Sagnac interferometer that connects the PCF is formed by applying the birefringence effect of melting cone coupling. The prepared interferometer is placed on a special optical platform, and graphene is coated on the fused cone area and the PCF. The excellent properties of graphene are utilized to measure humidity. Experimental results show that sensitivity to humidity is within the range of 36.0% relative humidity (RH)–75.3% RH, reaching 340.13pm/% RH. The sensor proposed in this study exhibits the characteristics of a simple structure, easy manufacturing, and low cost. It can be used as reference for the design and development of new sensors.

On the basis of the photoelectric properties and hydrophilicity and multimode interference of Graphene Oxide (GO), this study proposes an all-fiber humidity sensor. Two core-offset regions are constructed with a fiber fusion splicer, and a GO film is coated on a single-mode fiber (SMF) between the core-offset regions to form a humidity-sensitive Mach–Zehnder interference structure. As the external humidity environment changes, the refractive index of the GO changes, and the light in the SMF is modulated by humidity. External humidity is measured by detecting the changes in the wavelength of the transmission spectrum of the sensing structure. A saturated salt solution is used to build a stable humidity environment. The sensitivity of the sensor is 0.05 nm/% relative humidity (RH) at 35.3%–95.8% RH, and the linear relationship between the characteristic wavelength and RH is 88%. In addition, the linear relationship between the light intensity and the RH of the sensor at a single wavelength at 1571 nm is analyzed, and the linearity is 97.45%. According to this finding, photoelectric conversion is used to convert the light intensity signal into a voltage signal. The data are processed by a computer to achieve the real-time and visual monitoring of the humidity environment. The fiber optic humidity sensor proposed in this work has a simple structure, simple production, low cost, and high sensitivity. This work provides a new method for humidity sensing.

In this article, a liquid level and refractive index double-parameter sensor with single-mode fiber–tapered photonic crystal fiber (TPCF)–single-mode fiber structure is designed. We utilized the temperature-insensitive characteristics of photonic crystal fiber (PCF) to solve the crosstalk caused by temperature. Tapering techniques are adopted to increase the evanescent wave and the sensing region length of the PCF surface and improve the sensitivity and measurement range of the sensor. The liquid level and refractive index can be simultaneously detected through the mode analysis of the sensor's interference spectrum, along with the double-parameter matrix equation. Experimental results show that the maximum sensitivity of the sensor is 0.58466 nm/mm within a liquid level range of 0–10 mm (for an aqueous solution). The maximum sensitivity of the sensor is 195.969 nm/RIU within the refractive index range of 1.336–1.382. The sensor has simple structure and excellent sensing performance, as well as several application prospects in the fields of fuel storage and chemical liquid level measurement.

Low extinction ratio (ER) and high temperature cross-sensitivity are serious but common problems for most strain sensors based on Vernier effect. In this study, a hybrid cascade strain sensor of a Mach–Zehnder interferometer (MZI) and a Fabry–Perot interferometer (FPI) with high sensitivity and high ER based on Vernier effect is proposed. The two interferometers are separated by a long single-mode fiber (SMF). The MZI is used as the reference arm, which can be flexibly embedded in the SMF. The FPI is used as the sensing arm and the hollow-core fiber (HCF) as the FP cavity to reduce optical loss. Simulation and experiments have proven that this method can significantly increase ER. At the same time, the second reflective face of the FP cavity is indirectly spliced to increase the active length to improve the strain sensitivity. Through the amplification of Vernier effect, the maximum strain sensitivity is –649.18 p m / μ ε , and the temperature sensitivity is only 5.76 pm/ ∘ C . The magnetic field was measured by combining the sensor with a Terfenol–D (magneto–strictive material) slab to verify the strain performance, and the magnetic field sensitivity is –7.53 nm/mT . The sensor has many advantages and has potential applications in the field of strain sensing.

A novel alcohol-filled optical fiber sensor that consists of a single-mode fiber–photonic crystal fiber–single-mode fiber (SMF–PCF–SMF) structure is proposed and experimentally validated. The proposed sensor is based on a Mach–Zehnder interferometer, which is fabricated by splicing a section of uncoated photonic crystal fiber (PCF) between two short sections of single-mode fibers with a fiber fusion splicer. The air holes of the PCF are filled with alcohol to fabricate a refractive sensing probe that can detect changes in the external refractive index (RI). Experimental results show that changes in the external RI cause shifts in the positions of wavelength peaks. The sensitivity of the proposed structure reaches 386.66 nm/RIU under the external RI of 1.335–1.350. The linearity of the shift of the wavelength valley with RI is 97.9%. Construction methods for a measurement system based on the SMF–PCF–SMF structure are also proposed. Notably, voltage change indirectly reflects the change in the external RI. Given this characteristic, the SMF–PCF–SMF structure has potential applications in fiber-based RI sensing.

A new method for detecting micro-displacement by using fiber end-face microsphere coupling is proposed to realize an accurate detection of large-scale micro-displacement. This fiber end-face microsphere is equivalent to a lens, which has a certain convergence effect on light, thereby improving the coupling efficiency of the fiber. In the experiment, a single-mode fiber with a core diameter of 9 μm and a cladding diameter of 125 μm was used, and the fiber end face was cut by using a fusion splicer for manual discharge. The fiber end-face microspheres were obtained given the surface tension of the fiber. At an emission aligned with the center of the receiving fiber end-face microspheres, the distance between the two fiber microspheres changed, and the light intensity received by the receiving end-fiber microspheres also changed, thereby causing intensity modulation. Experiment results showed that the sensitivity of the sensor is 0.00401 dBm/μm in the range of 0–3725 μm displacement at room temperature with a linear fit of 94.79%.Thereinto, the sensitivity is 0.0064 dBm/μm in the range of 800–1775 μm with a linear fit of 99.88%. The sensor has a wide detection range, favorable linearity, rapid response, simple manufacturing process, and low cost. Furthermore, this sensor is suitable for working in a severe environment with strong electromagnetic interference and is popular and applicable to the field of micro-displacement detection.

The study proposed a temperature sensor based on distilled water cladding of the coupling region in the loop-fiber coupler, which was formed by folding a single-mode fiber, melting the taper region with an H2 flame, and using two adjacent fibers to obtain the interference in the coupling. Based on thermo-optical effect response and coupling interference principle, with increasing ambient temperature, the refractive index of the distilled water decreased, and the interference spectrum drifted. The experiment explored the relationship between different lengths of taper region and interference spectrum. When the taper region length was 30-35 mm, the interference spectrum improved. Results showed that the maximum sensitivity of the sensor was 151.35 pm/°C and linearity reached 99.99% when the temperature was within the range of 35 °C to 60 °C. Furthermore, we propose a low-cost demodulation scheme. The sensor had high sensitivity, good linearity, good stability, fast response, simple manufacturing process, and low cost. It has potential application value.

In this paper, a novel Magnetic fluid-filled optical fiber sensor consisting of a multimode-single mode-multimode (MM-SM-MM) fiber structure has been proposed and experimentally demonstrated. The proposed sensor is based on a Mach-Zehnder interferometer, which is fabricated by splicing a section of uncoated single mode fiber between two short sections of multimode fibers with a fiber fusion splicer. The micro-structure is sealed in a Magnetic fluid-filled capillary tube and the magnetic field sensing probe is formed. Variations in an external magnetic field is seen to cause changes in the refractive index of MF. This tunable change in the refractive index with magnetic field strengths between 0.6 mT to 21.4 mT produces a shift in the position of the peak of the wavelength. The shift of the valley wavelength with magnetic field intensity has a good linearity of up to 99.586%. The achieved sensitivity of the proposed magnetic field sensor is 0.12306 nm/mT. Furthermore, we also proposed the corresponding building methods of the measurement system based on the MM-SM-MM structure. It turned out that a voltage change indirectly reflects the change of the external magnetic field strength. This therefore provides the potential to fiber-based magnetic field sensing applications.

We introduce a novel method of non-diffractive Mathieu beams formation using a technique of ‘combined axicon and amplitude modulation’. First, the theoretical mechanism of generating Mathieu beams is analytically derived in detail using the stationary-phase method. Subsequently, we experimentally generate several kinds of Mathieu beams using an amplitude-type spatial light modulation (SLM)-plus-axicon setup. The experimental results show that the proposed method for generation of Mathieu beams is simple and flexible, and thus it is particularly suitable for generating the family of all kinds of non-diffractive Mathieu beams.

magnetic field sensor of air-gap Fabry–Perot fiber interferometersis proposed based on magnetostrictive effect. The sensor is consisted of single-model fiber (SMF), air-gap, no-core fiber (NCF) and magnetic fluid. Those are sealed in the capillary, SMF and NCF are connect with air chamber and magnetic fluid column. With the presence of an external magnetic field, air chamber cavity length changes because of the magneto-volume variation of magnetic fluids. This situation causes a change in the optical path difference. Detection of the drift of interference spectrum leads to the detection of the change in magnetic field. When the magnetic field is parallel to the direction in which the capillary is placed, the sensitivity is 0.2347 nm/mT; when the magnetic fluid is perpendicular to the direction in which the capillary is placed, the sensitivity is 0.325 nm/ mT. In addition to this new magnetic fluid sensor, a practical detection system is built, which relative error rate is less than 2%.

All-optical fiber liquid level–refractive index–temperature (LRT) sensor was proposed the basis of micro/nanofiber coupling ring (MFCR). Two twisted conventional communication optical fibers are tapered, merged, and refined in the preparation of MFCR. By detecting the sensing dips, the liquid level, refractive index and temperature can be measured respectively. The coupler will form two interference paths (odd and even modes) in x and y polarization states and the two slightly different lights superimpose to form the interference using strong evanescent field characteristics of fiber coupling in the process of gradual tapering. Results showed that maximum sensitivities of liquid level, refractive index, and temperature are 81.78 p m / m m , 586.74 n m / R I U , and 443.66 p m / °C, respectively, in the optical fiber coupler with a width of 8 μ m . The proposed sensor has the advantages of simple fabrication process, compact structure, low cost, and important application prospects in the detection of biomedical and chemical liquid level.

A novel sensor configuration consisting of TiO2 film and dual long-period fiber gratings (LPFG) with an in-between core-mode blocker (CMB) is proposed and numerically investigated. TiO2 film is on the cladding surface of separation fiber between two identical LPFGs and lossy mode resonance (LMR) is induced by a single cladding mode which is coupled from core mode by the first grating. Afterwards, the cladding mode influenced by LMR is recoupled into core mode by the second grating. As a result, the output spectrum is characterized as a dip in the top of a bandpass spectrum curve. The central wavelength of this dip is sensitive to surrounding refractive index and the numerical analysis reveals that the sensitivity reaches 5075 nm/RIU with excellent linearity. In this configuration, the bandwidth of attenuation dip is reduced in a great manner since LMR is induced by a single cladding mode. Moreover, this sensor configuration synthesizes the advantages of both LMR and LPFG, which offers additional degrees of freedom in the sensor design.

The fluorescence spectra of melamine in pure milk excite by the visible light was studied experimentally. The result shows that the melamine in pure milk exhibits an obvious fluorescence peak nearby 540 nm with the optimal excitation wavelength of 467 nm. As the concentration of melamine in pure milk increased, the fluorescence intensity would increase at first and then decrease. This new discovery provides a good theoretical basis for the practical detection of melamine. Meanwhile, combining photoelectric technology and computer technology, this paper processes a method which can be applied to practical detection. The new fluorescence phenomenon and the method we designed have an important reference value for the detection of melamine in pure milk in practice.

In this study, the magneto-birefringence effect of magnetic fluid (MF) is adopted to form an innovative fiber optic magnetic field sensor. The sensitive section is fabricated via a D-shaped microstructure inscribed in a high-birefringence fiber Sagnac loop with a femtosecond laser. The D-shaped microstructure facilitates good combination of the optical-fiber Sagnac interferometer with the magneto-birefringence effect of MF without suffering from absorption loss and manual alignment. Experimental results show the good performance of the magnetic field fiver sensor, particularly its high stable extinction ratio. Preliminary results are provided, and the magnetic field sensitivity of 0.0823 nm/mT can be further improved by increasing the depth and length of the D-shaped microstructure.

Optical design, together with applied optics, forms a complete system from basic theory to application theory, and it plays a very important role in professional education. In order to improve senior undergraduates' understanding of optical design, this course is divided into three parts: theoretical knowledge, software design and product processing. Through learning theoretical knowledge, students can master the aberration theory and the design principles of typical optical system. By using ZEMAX(an imaging design software), TRACEPRO(a lighting optical design software), SOLIDWORKS or PROE( mechanical design software), student can establish a complete model of optical system. Student can use carving machine located in lab or cooperative units to process the model. Through the above three parts, student can learn necessary practical knowledge and get improved in their learning and analysis abilities, thus they can also get enough practice to prompt their creative abilities, then they could gradually change from scientific theory learners to an Optics Engineers.

We reported a novel fiber sensor based on two cascaded single mode fiber corners, which has a high sensitivity for refractive index (RI) sensing and a low temperature crosstalk. RI sensing was experimentally demonstrated with an average sensitivity of 235 nm/RI unit in a RI range from 1.333 to 1.418, which is relatively high among the previously reported similar fiber sensors (e.g., it is about 10 times higher than that of the normal two or three-cascaded-taper based Mach–Zehnder interferometer). The proposed RI sensor was fabricated by fiber fusion splicer, where the fiber corner was fabricated by splicing the two overlapping single mode fibers, which ensures that the proposed RI sensor is compact and strong. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2642–2645, 2014

We construct and generate symmetric accelerating caustic beams (ACBs) by using 3/2-order phase-only masks with elliptical contour based on optical caustics and diffraction theory. The symmetric ACBs are a type of bimodal accelerating caustic beam with two quasi-constant intensity peaks, very similar to the combination of two face-to-face Airy-like beams judging by appearance. Their fundamental optical morphology and force properties of particles in ACBs are subsequently provided. The unique optical properties of ACBs can be exploited for practical uses, such as accelerating electrons and clearing micrometer-sized particles as a laser micrometer-sized "water pump" instead of a laser micrometer-sized "snowblower" of accelerating Airy beams.

We demonstrate a novel all-fiber refractometer which is a multimode-single mode-multimode (MM-SM-MM) fiber structure formed by splicing a section of uncoated single mode fiber (SMF) with two short sections of multimode fibers (MMFs). Owing to the core mismatch at the splicing points of the SMF with two sections of MMFs, part of the guided light propagates in the cladding of the SMF, which makes the SMF sensitive to the external refractive index (RI). RI sensing is achieved by measuring the wavelength shift of the interference pattern of the cladding mode and the core mode of the SMF. A RI sensor with an average sensitivity of 412 nm/RUI (refractive index unit) for a RI range from 1.333 to 1.400 is presented.

A novel highly birefringent photonic crystal fiber (PCF) is proposed based on a lattice structure of three-hole units. The three air holes in a line form the basic unit of the PCF which effectively acts as one elliptical air hole. The proposed PCF can achieve high birefringence similar to the elliptical air hole PCF with the same air-filling fraction. Properties such as birefringence, confinement loss, and mode area of the proposed PCF based three-hole units are investigated and compared with the elliptical air hole PCF and double-hole PCF. Our simulations show that the birefringence of the proposed PCF can be up to an order of 0.01 at low normalized frequency, and the size of the central air hole of the three air holes plays an important role in achieving the highest birefringence of the proposed PCF.

A novel temperature sensor based on a dual-core fiber (DCF) is proposed and theoretically analyzed. The DCF-based temperature sensor is simply formed by splicing a segment of DCF to two segments of single mode fibers, where the DCF is used as the sensing element. The mode coupling between two fiber cores of the DCF is sensitive to the temperature-induced index change of the silica in the DCF. Simulations show that there is a linear relationship between the temperature of the DCF and the wavelength shift of the output spectrum of the DCF-based temperature sensor when the broadband light is injected into one fiber core of the DCF. Temperature sensors based on DCFs with different parameters for temperature sensing are also investigated.

A dual-core photonic crystal flber (DC-PCF) is proposed, and bending characteristics of the DC-PCF are investigated. Two flber cores are employed in the cross-section of the DC-PCF, which result in a mode coupling between the two flber cores when the light propagates inside the DC-PCF. The mode coupling between two flber cores of the DC-PCF is sensitive to the directional bending of the DC-PCF which essentially provides a method to achieve bending sensing. A DC-PCF-based bending sensor is proposed by injecting a broadband light into one flber core of the DC-PCF on one side and detecting output spectrum from another flber core of the DC-PCF on the other side. In our simulations, a parabola curve which shows the relationship between the wavelength shift of the transmission spectrum of the DC- PCF-based bending sensor and the bending curvature of the DC-PCF is presented.

A novel strain sensor was proposed by splicing a dual-core photonic crystal fiber (DC-PCF) with two single-mode fibers. Owning to the mode index difference between the two fiber cores of DC-PCF, a Mach-Zehnder interferometer (MZI) pattern was achieved and its transmission spectrum is sensitive to the microstress of the DC-PCF. We analyze the stress characteristics of the fiber sensor with different lengths of DC-PCF. It shows that transmission spectrum pattern of the MZI shifts to the long wavelength with a sensitivity about 1.4pm/µe (for a 2-cm DC-PCF) and 1.9pm/µe (for a 4-cm DC-PCF) under an axial microstress. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2778–2780, 2014

The paper describes a new optical sensor for simultaneous liquid concentration and temperature measurement. Temperature-dependent semiconductor absorption at the band edge is used as the principle of the temperature measurement, and the sensor exploits beam deviation caused by refraction due to the liquid concentration at the receiving end face of the optical device. The light intensity peak value and its deviation are detected by a charge-coupled device (CCD), and then the measured optical signal is reflected by a reflecting pyramid prism. The sensor probe is composed of an intrinsically pure GaAs single crystal, a reflecting pyramid prism, a partitioned water cell. Theoretical analysis and preliminary experimental results verify the feasibility of the proposed system.

A tilt measurement structure and signal detection method is proposed based on a self-demodulated fiber-Bragg grating (FBG) sensor, which consists of a couple of matched FBGs and a cantilever-based pendulum clinometer. Compared by the typical matched FBGs demodulating method, of which a sensing FBG and a demodulating filter FBG is placed separately, both matched FBGs of this tilt sensor are attached on the upper and lower surface of only one single pendulum-type cantilever element for simultaneous sensing and demodulating. So the received light power will change due to the split of the two reflected spectrum of FBGs, which is corresponding to the tilt angle. In addition, the cross-sensitivity effect of the FBG-based sensor is automatically solved due to a differential signal process method. Experimental results indicate the feasibility of the proposed idea.

We reported two kinds of fiber sensor based on double cascaded single mode fiber corners, which has a high sensitivity for refractive index (RI) sensing. RI sensing was experimentally demonstrated with average sensitivity of 95.5nm/RI unit (RIU) in a RI range from 1.333 to 1.421 and the other is 235nm/RI unit (RIU) from 1.333 to 1.418, which are relatively high among the previously reported similar fiber sensors (e.g., it is about 10 times higher than that of the normal two or three-cascaded-taper based Mach–Zehnder interferometer). Besides, The proposed RI sensors were fabricated only by a fiber fusion splicer. So , the fiber sensor is quite easy to made.

Based on a free active cylinder bulk-modulus and the birefringence effect on a fiber Bragg grating (FBG), pressure measurement is implemented by demodulating fiber Bragg grating peak splitting caused by transverse stress differences in the core of a single mode fiber, which is bonded on the exterior surface of the cylinder. The two orthogonally polarized signals reflected from the compressed fiber Bragg grating (FBG) can be independently detected with a simple FBG interrogation system, which is based on the light intensity measurement method. In addition, the cross-sensitivity of temperature and strain of FBG sensor can be self-compensated by this method. Measurement principle is introduced, preliminary experimental results indicate that the measurement sensitivity is estimated to be ∼27 pm/Mpa in a measurement range from standard atmosphere pressure to 100 MPa.

A free active element bulk-modulus based fiber Bragg grating (FBG) high pressure sensor and self-demodulation method for FBG wavelength shift signals are presented. With a simple isosceles triangle cantilever structure, problems of cross-sensitivity and chirped-signal in FBG sensor and are solved. In addition, unlike other FBG-based sensors which have separated sensing and demodulating element, this FBG-based high pressure sensor has only a single structure unit for both sensing and demodulating. Measurement principle and theoretical analysis are introduced. Simulation results and preliminary experimental results indicate that the measurement resolution of pressure can reach 0.1 MPa in a range from standard atmosphere pressure to 100 MPa.

A fiber bending sensor by splicing a segment of two mode fiber to the single mode fiber is proposed.The two mode fiber with an external diameter (fiber core diameter) of 145 μm (17.65 μm) can only support the fundamental mode (LP01 mode) and the second mode (LP11 mode), which results in an interfering spectrum of the fiber bending sensor. The interfering spectrum has an extinction ratio of about 10 dB in 1.55 μm window, and the fiber bending curvature is measured corresponding to the shift of the interfering spectrum. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1047–1049, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26734

The fluorescence spectra of melamine-contained milk solution excited by the exciting light have been experimentally studied in this paper. The experiments show that the melamine-contained milk solution can produce strong fluorescence when excited by 467nm exciting light. The fluorescence spectrum peak is around 540nm and the fluorescence intensity would increase firstly and then decrease with the increasing concentration of melamine in pure milk. Based on this result, combining with the optical technology and computer technology, a simple detection system device has been designed. The device can quickly detect whether the milk containing melamine in real-time and accurately show the concentration of melamine in a certain range, which make the device have strong practicability.

A dual-core photonic crystal fiber (DC-PCF) sensor based on fiber Mach-Zehnder interferometer is proposed and demonstrated for stress sensing with a sensitivity of 1.4 pm/µe and hydraulic pressure sensing with a sensitivity of −41 pm/MPa.

Thermal effect of optical system is the key factor influencing high resolution image quality for airborne CCD camera, athermalization is the key technology and leading topic in optical engineering field. The researh field focus on infrared system, however, the visible system is quite few considered. Based on optical compensation method, the conception of general zoom system was proposed to realize athermal design for complex visible refractive system. Three steps of the athermalization was considered as three status of zoom system design, correspondence between the athermal design and zoom system design was established. Firstly a good optical system was designed to satisfy image quality in normal temperature, and then multiple zooming positions were established in actual temperature range from -40° C to +60° C , the excellent imaging quality was obtained by replacing partial materials properly. An optical system in the 0.43um, 0.75um waveband was designed with 650mm focal length, F/5.6 F-number, 5.5° field-of-view by the general zoom method. The results showed the image quality had a reliable performance with -40° C +60° C , and the MTF is higher than 0.5 at the spatial frequency of 70lp/mm, image quality reached the diffraction limit. The MTF decreased only with 5%, the athermal design can meet high resolution requirement for airborne CCD camera in wide temperature range. The atheraml research for visible optical system will further complete athermal theories and technologies, and its study and applications will produce important value for military airborne optical system and space optical system.

A research on distributed Fiber Bragg grating (FBG) demodulation system is based on tilted Fiber Bragg grating (TFBG). In order to separate temperature effect with fiber Bragg grating, we use two adjacent FBG (one used for sense, the another for reference ) which have the same central wavelength but different grating length, by parallel connection to make a sensing probe; Put the FBG keep close to equal thickness of rigidity cantilever beam of isosceles triangle, demodulate spectrum signal from sensing probe by using optical properties of main mode and side mode of TFBG and mechanical properties of cantilever. With the help of a computer to control cantilever beam's cyclic oscillating and collect transmission spectrum signals of TFBG at the same time, analytical processing data for real time display of await strain. Experimental results show that it is feasible to demodulate distributed optical Fiber Bragg grating by TFBG (resolution of micro-strain is 0.009 μe ), which solves the cross sensitivity of temperature and strain. The system is stably and reliable, low cost.

In order to meet the requirement of inspecting fiber connector end face, a new detection system based on digital holographic microscopy is designed and the method to reconstruct three- dimensional image of the end face is proposed. Experimental results show that the technology can inspect the concentricity of fiber connector end face, the ellipticity of fiber core and the cladding and other parameters. Meanwhile the three-dimensional shape of fiber connector end face can be obtained.

According to the deficiencies of static demodulating method of Arrayed Waveguide Grating (AWG) for Fiber Bragg Grating (FBG) reflecting wave wavelength and the characteristic of central wavelength of tunable AWG shifting with applied voltage, the dynamic demodulating method based on tunable AWG for FBG's central wavelength wide-range is presented. The experiment systems are set up with tunable AWG, adjustable voltage source, photomultiplier, data acquisition card, and computer. Experiment results show that the system can effectively resolve the problems of measurement wide-range off-centering for the FBG, and computer can real-timely report the results of off-centering of the FBG central wavelength. AWG with the 2nm channel-spacing is used to demodulate, and the off-centering range of reflecting wave wavelength of the measured FBG reach 6nm, its measurement error is less than 0.02%.

Based on the Arrayed Waveguide Grating (AWG) equation and output light intensity equation, dual peaks electro-optical AWG is presented, whose properties are analyzed in details in the paper. The experiments for the electro-optical dual peaks AWG are simulated by Optiwave software, and the experimental results verify the theory very well.