Showing papers on "Radiation mode published in 2014"
TL;DR: The proposed fiber sensor has sensitivity of refractive index around 1500 nm/RIU and for protein concentration detection, its highest sensitivity is 2.42141 nm/%W/V.
Abstract: We demonstrate refractive index sensors based on single mode tapered fiber and its application as a biosensor. We utilize this tapered fiber optic biosensor, operating at 1550 nm, for the detection of protein (gelatin) concentration in water. The sensor is based on the spectroscopy of mode coupling based on core modes-fiber cladding modes excited by the fundamental core mode of an optical fiber when it transitions into tapered regions from untapered regions. The changes are determined from the wavelength shift of the transmission spectrum. The proposed fiber sensor has sensitivity of refractive index around 1500 nm/RIU and for protein concentration detection, its highest sensitivity is 2.42141 nm/%W/V.
157 citations
TL;DR: An ultra-compact TE0-TE1 mode converter obtained in a photonic crystal waveguide is experimentally demonstrated by utilizing topology optimization and shows a ~39 nm bandwidth around 1550 nm with an insertion loss lower than ~3 dB.
Abstract: We have designed and for the first time experimentally verified a topology optimized mode converter with a footprint of ~6.3 μm × ~3.6 μm which converts the fundamental even mode to the higher order odd mode of a dispersion engineered photonic crystal waveguide. 2D and 3D topology optimization is utilized and both schemes result in designs theoretically showing an extinction ratio larger than 21 dB. The 3D optimized design has an experimentally estimated insertion loss lower than ~2 dB in an ~43 nm bandwidth. The mode conversion is experimentally confirmed in this wavelength range by recording mode profiles using vertical grating couplers and an infrared camera. The experimentally determined extinction ratio is > 12 dB and is believed to be limited by the spatial resolution of our setup.
132 citations
TL;DR: In this paper, mode instability in a 500 W terbium-doped fiber laser is experimentally examined by changing the pumping wavelength, spectral bandwidth of signal light, active fiber temperature and coiling radius.
Abstract: In this paper mode instability in a 500 W ytterbium-doped fiber laser is experimentally examined by changing the pumping wavelength, spectral bandwidth of signal light, active fiber temperature and coiling radius. The magnitude of power transfer from the fundamental mode to the higher order mode due to mode instability is measured as a criterion for its incident. The experiments show that the coiling radius of the first few tens of centimeters of the active fiber plays a significant role in controlling mode instability, and shifting the pumping wavelength from 976 to 973 nm can mitigate mode instability.
68 citations
TL;DR: A new type of hollow-core fiber is reported, showing for the first time distinct transmission windows between the deep ultraviolet and the near infrared, and operating by the central core mode being anti-resonant to adjacent modes, leading to a novel modified tunneling leaky mode.
Abstract: Guiding light inside the hollow cores of microstructured optical fibers is a major research field within fiber optics. However, most of current fibers reveal limited spectral operation ranges between the mid-visible and the infrared and rely on complicated microstructures. Here we report on a new type of hollow-core fiber, showing for the first time distinct transmission windows between the deep ultraviolet and the near infrared. The fiber, guiding in a single mode, operates by the central core mode being anti-resonant to adjacent modes, leading to a novel modified tunneling leaky mode. The fiber design is straightforward to implement and reveals beneficial features such as preselecting the lowest loss mode (Gaussian-like or donut-shaped mode). Fibers with such a unique combination of attributes allow accessing the extremely important deep-UV range with Gaussian-like mode quality and may pave the way for new discoveries in biophotonics, multispectral spectroscopy, photo-initiated chemistry or ultrashort pulse delivery.
60 citations
TL;DR: In this paper, a combination of frequency analysis and far-field imaging for high mode numbers of large whispering-gallery mode resonators is proposed to identify the radial mode numbers q and the angular mode numbers p = l-m.
Abstract: Identifying the mode numbers in whispering-gallery mode resonators (WGMRs) is important for tailoring them to experimental needs. Here we report on a novel experimental mode analysis technique based on the combination of frequency analysis and far-field imaging for high mode numbers of large WGMRs. The radial mode numbers q and the angular mode numbers p = l-m are identified and labeled via far-field imaging. The polar mode numbers l are determined unambiguously by fitting the frequency differences between individual whispering gallery modes (WGMs). This allows for the accurate determination of the geometry and the refractive index at different temperatures of the WGMR. For future applications in classical and quantum optics, this mode analysis enables one to control the narrow-band phase-matching conditions in nonlinear processes such as second-harmonic generation or parametric down-conversion.
58 citations
TL;DR: It is demonstrated that the nondestructive measurement of mode coupling along a few-mode fiber using a synchronous multi-channel OTDR with a 10-m spatial resolution is successfully obtained.
Abstract: We describe the nondestructive measurement of mode coupling along a few-mode fiber using a synchronous multi-channel optical time-domain reflectometer (OTDR). By installing a few-mode fiber (FMF) coupler made with a phase mask method, we excite the LP01 mode in an FMF under the test as an input mode, and then we detect backward Rayleigh scattered LP11a or LP11b modes, which were generated as a result of the mode coupling through the coupler. The mode coupling distribution between the LP01 and LP11a,b modes along the test FMF was successfully measured with a 10-m spatial resolution by obtaining the ratio between the backscattered LP01 mode and LP11a or LP11b. The value of the mode coupling obtained with the present method agreed well with that obtained with the conventional transmission method.
55 citations
TL;DR: This mode converter is used to couple light into and out of a 320 nm slot photonic crystal waveguide, and it is experimentally shown to improve the coupling efficiency up to 3.5 dB compared to the V-shape mode converter, over the slow-light wavelength region.
Abstract: We design, fabricate and experimentally demonstrate a highly efficient adiabatic mode converter for coupling light into a silicon slot waveguide with a slot width as large as 320 nm. This strip-to-slot mode converter is optimized to provide a measured insertion loss as low as 0.08 dB. Our mode converter provides 0.1 dB lower loss compared to a conventional V-shape mode converter. This mode converter is used to couple light into and out of a 320 nm slot photonic crystal waveguide, and it is experimentally shown to improve the coupling efficiency up to 3.5 dB compared to the V-shape mode converter, over the slow-light wavelength region.
50 citations
TL;DR: A novel mode converter in silicon waveguide is designed, analyzed and experimentally demonstrate based on a graded index co-directional grating coupler based on the basis of numerical simulations and microscope images of modes' far field.
Abstract: We propose, design and analyze a novel mode converter in silicon waveguide based on a graded index co-directional grating coupler. The device has a periodic variation in its refractive index along the propagation direction and a graded index profile along the transverse direction. The graded index profile is realized by the implementation of nanoscale dielectric metamaterial consisting of silicon features that are etched into the waveguide based on the concept of effective medium. Design considerations are discussed and analyzed in details in the framework of the coupled mode theory (CMT) and the effective medium theory (EMT). Using 3D finite difference time domain (FDTD) simulations we show that the mode converter can couple between different symmetric and asymmetric modes which are propagating along a single bus multimode waveguide. Mode purity on the order of 96%, crosstalk with the input mode of better than −23dB, and transmission of more than 96% can be obtained, with device length as short as 20µm, and over ~25nm spectral bandwidth around the design wavelength of 1550nm.
49 citations
TL;DR: A double-nanospike As2S3-silica hybrid waveguide structure is reported, which is numerically optimized to match both the diameter and divergence of the input beam, resulting in efficient excitation of the fundamental mode of the waveguide.
Abstract: A double-nanospike As2S3–silica hybrid waveguide structure is reported. The structure comprises nanotapers at input and output ends of a step-index waveguide with a subwavelength core (1 μm in diameter), with the aim of increasing the in-coupling and out-coupling efficiency. The design of the input nanospike is numerically optimized to match both the diameter and divergence of the input beam, resulting in efficient excitation of the fundamental mode of the waveguide. The output nanospike is introduced to reduce the output beam divergence and the strong endface Fresnel reflection. The insertion loss of the waveguide is measured to be ∼2 dB at 1550 nm in the case of free-space in-coupling, which is ∼7 dB lower than the previously reported single-nanospike waveguide. By pumping a 3-mm-long waveguide at 1550 nm using a 60-fs fiber laser, an octave-spanning supercontinuum (from 0.8 to beyond 2.5 μm) is generated at 38 pJ input energy.
47 citations
TL;DR: This Letter presents both numerical and experimental results of a strip-slot mode converter based on symmetric multimode interference (MMI), which makes full use of the symmetry of the two-fold image of MMI, and its field distribution similarity with a slot waveguide to convert the mode.
Abstract: Optical mode mismatch makes coupling between strip and slot waveguides a tough issue in integrated photonics. This Letter presents both numerical and experimental results of a strip-slot mode converter based on symmetric multimode interference (MMI). Distinct from previous reported converters which gradually convert the mode through sharp tips, the proposed solution makes full use of the symmetry of the two-fold image of MMI, and its field distribution similarity with a slot waveguide to convert the mode. A converter based on this mechanism is able to convert light from a TE-polarized fundamental mode of a strip waveguide to that of a slot waveguide, and vice versa. Strip-slot waveguide coupling though this mode converter has a measured efficiency of 97% (−0.13 dB), and the dimensions are as small as 1.24×6 μm. Further analysis shows that the proposed converter is highly tolerant to fabrication imperfections, and is wavelength-insensitive.
44 citations
TL;DR: In this article, a single mode circular photonic crystal fiber (C-PCF) was proposed for broadband dispersion compensation covering 1400 to 1610nm wavelength band over the telecommunication windows.
TL;DR: An integral representation which describes the radiation produced by a single waveguide mode in the Fraunhofer zone is obtained and it is shown that for a mode with large mode number, the aperture of the vacuum channel gives the main contribution to the field if the skew angle of the waveguide aperture is not too small.
Abstract: We analyze radiation produced by an ultrarelativistic charge as it exits the open end of a cylindrical waveguide with a dielectric lining. The end of the waveguide can be either orthogonal to the structure axis or skewed. To obtain terahertz radiation from waveguides with centimeter or millimeter radii, we consider high order TM0m modes driven by the beam. We obtain an integral representation which describes the radiation produced by a single waveguide mode in the Fraunhofer zone. We perform a series of numerical calculations for structures which look promising for generation of THz radiation. It is shown that for a mode with large mode number, the aperture of the vacuum channel gives the main contribution to the field if the skew angle of the waveguide aperture is not too small. Simple expressions for the angle of the main pattern lobe maximum are obtained.
TL;DR: Experimental and theoretical analysis revealed the nonlinear power transformation of the LP(01) fundamental mode into high-order modes and self-consistent growth of the higher-order mode and traveling electronic index grating accompanying the population grating induced by the mode interference field.
Abstract: Spatio-temporal instability of the fundamental mode in Yb3+-doped few-mode PM fiber amplifiers with a core diameter of 8.5 μm was registered at 2-30 Watts pump power. Both experimental and theoretical analysis revealed the nonlinear power transformation of the LP01 fundamental mode into high-order modes. Numerical simulation revealed self-consistent growth of the higher-order mode and traveling electronic index grating accompanying the population grating induced by the mode interference field (due to different polarizability of the excited and unexcited Yb3+ ions). Experimental results and numerical calculations showed the increase of the instability threshold along with an increase of the signal frequency bandwidth.
TL;DR: In this article, a Mach-Zehnder interferometer based on singlemode-thin-core-multimode-singlemode (STMS) fiber structure for refractive index (RI) measurement is proposed and experimentally demonstrated.
Abstract: A Mach-Zehnder interferometer based on single-mode-thin-core-multimode-single-mode (STMS) fiber structure for refractive index (RI) measurement is proposed and experimentally demonstrated. It works on the basis of interference between the core mode and cladding mode. Using the multimode fiber core, the transmission spectrum of STMS structure is very sensitive to RI variations of the surrounding medium. The experimental results show that the sensor possesses a high sensitivity of 148.27 nm/RIU in the RI range of 1.333-1.403 and has a good linear response to the SRI.
TL;DR: The mechanisms of gain saturation have not only a profound impact on the complex temporal-spectral behavior but also explains mode clustering in (Al,In)GaN laser diodes, both in pulsed and continuous wave (cw) operation as a natural nonlinear effect without the necessity to add noise.
Abstract: Longitudinal mode competition in (Al,In)GaN laser diodes at λ = 445nm and 515 nm with mode competition frequencies from 10 MHz to 150 MHz is observed. Up to two dozen lasing modes oscillate with the lasing mode rolling from the short wavelength edge to the long wavelength edge of the gain profile. The experimental results can be described very well with a set of multi–mode rate equations including self–, symmetric and asymmetric cross gain saturation. By tuning essential parameters of the gain saturation terms, mode competition disappears and single mode operation as well as mode clustering is found. This proves that the mechanisms of gain saturation have not only a profound impact on the complex temporal–spectral behavior but also explains mode clustering in (Al,In)GaN laser diodes, both in pulsed and continuous wave (cw) operation as a natural nonlinear effect without the necessity to add noise.
TL;DR: This letter employs silicon oxynitride with RI about 1.50 as the intermediate material and optimize the structure of the SiON waveguide to match with cleaved single mode fiber and HIC waveguide separately, and reduces the mismatching loss.
Abstract: High-index-contrast (HIC) waveguide such as Si and Si3N4 has small mode size enabling compact integration. However, the coupling loss with single mode fiber is also remarkable owning to the mode mismatching. Therefore, mode size converter, as the interface between HIC waveguide and optical fiber, takes an important role in the field of integrated optics. The material with refractive index (RI) between HIC waveguide and optical fiber can be used as a bridge to reduce the mode mismatching loss. In this letter, we employ silicon oxynitride (SiON) with RI about 1.50 as the intermediate material and optimize the structure of the SiON waveguide to match with cleaved single mode fiber and HIC waveguide separately. Combined with inverse taper and suspended structure, the mismatching loss is reduced and the dependence to the dimension of the structure is also released. The coupling loss is 1.2 and 1.4 dB/facet for TE and TM mode, respectively, with 3 dB alignment tolerance of ± 3.5 μm for Si(3)N(4) waveguide with just 200 nm-wide tip. While for Si waveguide, a critical dimension of 150 nm is applied due to the higher index contrast than Si(3)N(4) waveguide. Similar alignment tolerance is realized with coupling loss about 1.8 and 2.1 dB/facet for TE and TM mode. The polarization dependence loss (PDL) for both platforms is within 0.5 dB.
TL;DR: In this article, an ultra-thin polymer optical waveguide couplers for integrated optics based on Bloch surface waves (BSWs) are presented, where the waveguide thickness is on the order of λ/15.
Abstract: Ultra-thin polymer optical waveguide couplers for integrated optics based on Bloch surface waves (BSWs) are presented. Desirable BSW guiding properties, such as low loss and long propagation distance, are observed. The waveguide thickness is on the order of λ/15. At 1562 nm wavelength, a coupling length of 250 μm is found for 3 μm wide waveguides separated by 1 μm. The second-order mode is also investigated; we show that the fundamental mode can be excited by the second-order mode. The effect of variations in the waveguide width, gap, and refractive index are theoretically investigated by studying their impacts on the coupling length. Results are promising for mode division multiplexing, optical sensors, and optical communications.
TL;DR: A TE01-HE11 mode conversion system has been built to test launching HE11 microwave power into the plasma chamber in VENUS, and draws on the development of similar devices used in tokamaks and stellerators.
Abstract: A number of superconducting electron cyclotron resonance (ECR) ion sources use gyrotrons at either 24 or 28 GHz for ECR heating. In these systems, the microwave power is launched into the plasma using the TE01 circular waveguide mode. This is fundamentally different and may be less efficient than the typical rectangular, linearly polarized TE10 mode used for launching waves at lower frequencies. To improve the 28 GHz microwave coupling in VENUS, a TE01-HE11 mode conversion system has been built to test launching HE11 microwave power into the plasma chamber. The HE11 mode is a quasi-Gaussian, linearly polarized mode, which should couple strongly to the plasma electrons. The mode conversion is done in two steps. First, a 0.66 m long “snake” converts the TE01 mode to the TE11 mode. Second, a corrugated circular waveguide excites the HE11 mode, which is launched directly into the plasma chamber. The design concept draws on the development of similar devices used in tokamaks and stellerators. The first tests o...
TL;DR: In this paper, a complete theoretical model on the stimulated Brillouin scattering (SBS) for multi-mode fibers was developed by solving the optical-acoustic coupling wave equations.
Abstract: A complete theoretical model on the stimulated Brillouin scattering (SBS) for multi-mode fibers (MMF) is developed by solving the optical-acoustic coupling wave equations. It shows that all optical modes of the signal and of SBS are coupling each other through proper acoustic waves. The Brillouin gain spectrum of each optical mode pair is obtained by certain three-wave couplings (optical-acoustic-optical). The model is further coupled with an optical amplification model on the fiber lasers to take the mode competition into account. By applying the model to a large mode-area double cladding fiber, it is found that the multi-acoustic mode combination plays an important role in the SBS coupling between optical higher order modes (HOM). While for double-mode (fundamental mode +HOM) performance, the SBS threshold increases gradually along with the increase of HOM content. It is also found that the SBS process in the fiber amplifiers can be completely different comparing with that of the passive fiber, because the mode competition not only changes the mode contents of the signal power but also influences the initial growth rate of SBS noise. The Al/Ge co-doped MMF is investigated theoretically as well, and is shown to be able to suppress SBS significantly. Finally we compare our model with a SBS experiment for a MMF, main theoretical predictions agree with the experiment well.
TL;DR: The proposed waveguide consists of two dielectric nanowires placed on both sides of a nanowedge-patterned metal film, which can confine light in the ultra-deep-subwavelength region and has good tolerance of fabrication errors.
Abstract: In this Letter, a novel waveguide based on hybrid surface plasmon polaritons (HSPPs) is proposed and numerically analyzed. This waveguide consists of two dielectric nanowires placed on both sides of a nanowedge-patterned metal film, which can confine light in the ultra-deep-subwavelength region (ranging from λ2/4000 to λ2/400) with a long propagation length (ranging from 1200 to 3500 μm). Compared to a previous HSPPs waveguide without the nanowedges, with the same propagation length, our proposed structure has much higher mode confinement with 1 order of magnitude smaller normalized mode area. An investigation of the effect of structural perturbations indicates that our proposed waveguide also has good tolerance of fabrication errors. The proposed waveguide could be an interesting alternative structure to realize nanolasers and optical trapping.
TL;DR: In this paper, a numerical analysis of periodic segmented waveguides (PSWs) using the 2D finite element method (2D-FEM) in the frequency domain is presented.
Abstract: A numerical analysis of periodic segmented waveguides (PSWs) using the 2-D finite element method (2D-FEM) in the frequency domain is presented. This method has significantly lower computational cost when compared with 3-D methods that have been used to model PSWs, and can also model back reflected signals. Unlike photonic crystal waveguides, light confinement in a PSW is due to total internal reflection as in a continuous waveguide (CWG). We show that the dispersion relation of the guided modes in PSW is strongly influenced by the dielectric periodicity along the waveguide. We calculate the mode profile of a PSW in a region far away from the bandgap and we showed that it is comparable to the mode profile of the equivalent CWG even for relatively high values of averaged refractive index contrast.
TL;DR: It is shown that by appropriate choice of the length of the central multimode fiber one can obtain > 90% of the total core power in a chosen mode.
Abstract: We analyze the transmission of a Single mode - Multimode -Multimode (SMm) fiber structure with the aim of exciting a single radial mode in the second multimode fiber. We show that by appropriate choice of the length of the central multimode fiber one can obtain > 90% of the total core power in a chosen mode. We also discuss methods of removing undesirable cladding and radiation modes and estimate tolerances for practical applications.
TL;DR: In this paper, an optical mode interleaver (OMIL) based on the asymmetric multimode Y junction is proposed for realizing flexible selection of group of modes in mode-division multiplexing optical network.
Abstract: An optical mode interleaver (OMIL) based on the asymmetric multimode Y junction is proposed for realizing flexible selection of group of modes in mode-division multiplexing optical network. The odd and even modes of the stem can be sorted by carefully controlling the widths of the narrow and wide arms according to the constraint conditions of the propagation constants. A four-mode OMIL is analyzed as an example using the beam propagation method. The device is able to realize a low excess loss of <;0.13 dB, a high mode extinction ratio that exceeded 28.4 dB, and a mode crosstalk lower than -25.5 dB over a common spectral bandwidth of 210 nm.
TL;DR: A novel (to the authors' knowledge) hybrid plasmonic (HP) hollow waveguide is proposed for nanoscale optical confinement and the light is guided, with improved propagation characteristics, in an air slice sandwiched between metal and silicon.
Abstract: A novel (to our knowledge) hybrid plasmonic (HP) hollow waveguide is proposed for nanoscale optical confinement. The light is guided, with improved propagation characteristics, in an air slice sandwiched between metal and silicon. The optical mode in silicon is dragged toward the metal–dielectric (air) interface to make it a HP mode by optimizing the waveguide dimensions. In comparison to the hybrid mode confined in the dielectrics, the air-confined hybrid mode exhibits a smaller effective mode area Am=0.0685/μm2 and longer propagation distance Lp=142 μm with a low modal propagation loss of 0.03 dB/μm at optimized values of the width and height of the air slice.
TL;DR: In this article, a core-cladding-mode interferometer is fabricated by splicing a singlemode fiber to an endlessly single-mode photonic crystal fiber (ESM-PCF).
Abstract: A core-cladding-mode interferometer is fabricated by splicing a single-mode fiber to an endlessly single-mode photonic crystal fiber (ESM-PCF). The optimum collapsed length of ESM-PCF is investigated to ensure a higher order cladding mode of ESM-PCF to be excited, serving as a sensing beam. At the end of ESM-PCF, a spherical end-facet with big radius is proposed to ensure from where the higher order cladding mode is to be reflected and then it interferes with the core mode serving as a reference beam. Such a device has an enhanced refractive index sensitivity of ~ 199 nm/RIU, offering potentials in biological and chemical applications.
Patent•
22 Jul 2014
TL;DR: In this article, a directional coupler consisting of a first optical waveguide core 40 and a second OW core 50 which are arranged separated from and in parallel to each other, and propagate one m-th mode (m is an integer of 1 or more) polarization of TE polarization and TM polarization, and the other n-th modes (n is aninteger of 0 or more).
Abstract: PROBLEM TO BE SOLVED: To provide a directional coupler that can be used independently of polarization and has a high degree of freedom of design for a thickness of an optical waveguide core.SOLUTION: A directional coupler comprises a first optical waveguide core 40 and a second optical waveguide core 50 which are arranged separated from and in parallel to each other, and propagate one m-th mode (m is an integer of 1 or more) polarization of TE polarization and TM polarization, and the other polarization of n-th mode (n is an integer of 0 or more). Settings are made of a clearance D1 between the first optical waveguide core 40 and the second optical waveguide core 50, a width W1 of the first optical waveguide core, and a width W2 of the second optical waveguide core, so that, between the first optical waveguide core 40 and the second optical waveguide core 50, a mode coupling coefficient of p-th mode (p is an integer satisfying 0≤p≤m) of the one polarization is matched with a mode coupling coefficient of q-th mode (q is an integer satisfying 0≤q≤n) of the other polarization.SELECTED DRAWING: Figure 1
TL;DR: In this article, a self-written waveguide (SWW) is formed by illuminating a photosensitive polymerization mix with light emanating from the fiber, after which the exposed part polymerizes.
Abstract: A low-loss polymer medium to interconnect 2 single mode optical fibers is developed and characterized. It consists of a so-called self-written waveguide (SWW) formed by illuminating a photosensitive polymerization mix with light emanating from the fiber, after which the exposed part polymerizes. Depending on the material system used, this waveguide can have a step index or graded refractive index profile. The fabrication process and its effect on the waveguide performance are explained using an empirical model and afterwards experimentally verified. This approach enables easy process monitoring and optimization, effectively resulting in total insertion losses below 0.3 dB for a single mode fiber-SWW-fiber transition at 1550 nm.
TL;DR: In this article, the authors demonstrate a highly efficient acoustooptic mode converter for selective excitation of the higher-order modes in a four-mode fiber which guides the LP01, LP11, LP21, and LP02 modes at telecommunication wavelengths.
Abstract: We demonstrate a highly efficient acoustooptic mode converter for selective excitation of the higher-order modes in a four-mode fiber which guides the LP01, LP11, LP21, and LP02 modes at telecommunication wavelengths. The coupling efficiency and the mode extinction ratio are measured by analyzing the output far-field patterns. The acoustic resonance frequencies and the operating bandwidths are compared with the theoretical results, by which the modal characteristics, the core diameter, and the core-cladding index difference are estimated.
TL;DR: The proposed compact in-line modal interferometer is polarization-dependent and the adjacent interference fringes according to different components of LP(11) mode show greatly discrimination in sensitivities of temperature and strain, making it a good candidate for multiple physics parameters measurements.
Abstract: A compact in-line modal interferometer based on a long period grating (LPG) inscribed in water-filled photonic crystal fiber (PCF) is proposed and demonstrated. The interferometer works from the interference between fundamental core mode and different vector components of LP11 core mode. The LPG is especially inscribed to realize the energy exchange between the fundamental core mode and different vector components of LP11 core mode in the PCF. We build a complete theoretical model and systematically analyze the multi-component-intermodal-interference mechanism of the interferometer based on coupled-mode theory. Due to the asymmetric index distribution over the cross section of the PCF caused by CO2-laser side illumination, the dispersion curves and temperature sensitivities referring to different vector components of LP11 core mode are quite different. Thus the interferometer is polarization-dependent and the adjacent interference fringes according to different components of LP11 mode show greatly discrimination in sensitivities of temperature and strain, making it a good candidate for multiple physics parameters measurements.
TL;DR: This study proposes a specially-engineered tapered waveguide unit for the simultaneous satisfaction of the generation of the non- or less-dispersive wave and the transmission of a narrow-beam wave into a test structure.