Machining of acrylic-based Y-branch plastic optical fiber coupler with suspended waveguide taper

An acrylic-based Y-branch plastic optical fiber (POF) with a middle suspended waveguide taper has been developed. The suspended high index contrast waveguide taper structure has been designed in such a way that it is surrounded by air-cladding. Non-sequential ray tracing has been performed on the device giving an insertion loss of 4.68 dB and coupling ratio of 50: 50. The middle waveguide taper is constructed on the acrylic block itself without using any additional optical waveguiding medium injected into the engraved taper region. Fabrication of the devices is done by producing the device structures on an acrylic block using high speed computer numerical control (CNC) machining tool. Input and output POF fibers are inserted into this device structure in such a way that they are passively aligned to the middle waveguide taper structure. The device shows an insertion loss of 5.9 dB, excess loss of 2.9 dB and a splitting ratio of 50: 50.     

Acrylic-based asymmetric and variable coupling ratio Y-branch plastic optical fiber coupler

Acrylic-based asymmetric and variable couplers have been developed using a single structured Y-branch design with a high-index-contrast waveguide taper and a void structure for fiber attenuation using the lateral displacement of two fibers. Device fabrication is performed by producing the device structure on an acrylic block using a computer numerical control (CNC) machine tool. The fabricated device has an excess loss of 5.85 dB, while the coupling ratios are 56.86 and 43.14% when the device is operated as a 3 dB coupler. In the asymmetric coupler mode, the coupling ratio ranges from 44.84 to 8.01% for port 1 and 55.16 to 91.99% for port 2. The excess loss of this device varies from 5.42 to 7.64 dB. In the variable coupler mode, the coupling ratio ranges from 10.09 to 32.88% for port 1 and from 89.91 to 67.12% for port 2. The excess loss of the device varies from 5.85 to 8.49 dB.     

Design and fabrication of a three-dimensional polymer optical waveguide polarization splitter

We present a design and fabrication of a three-dimensional polymer optical waveguide polarization splitter by taking into consideration of the induced birefringence effect of the polymer. We show that it is not possible to couple TM light from one waveguide to the other but evanescent coupling for TE light is possible. Hence the polarization splitter can be designed by considering TE mode coupling alone. This has an advantage of short interaction length of the device. Based on this consideration, we fabricated a polarization splitter with a TE extinction ratio of 15 dB and TM extinction ratio of 21 dB.     

Polymer waveguide module for visible wavelength division multiplexing plastic optical fiber communication

We report a polymer waveguide module that provides bidirectional communication over a single plastic optical fiber (POF) with dual visible wavelength LEDs. The module is constructed using light-induced self-written waveguides, which enables a three-dimensional optical circuit for visible wavelength division multiplexing to be fabricated by an extremely simple process. We demonstrated 250 Mbits/s communication using a pair of these modules that each contained one green (lambda = 495 nm) and one red (lambda = 650 nm) LEDs by measuring the bit error rates. The results indicate that the system could transmit over more than 20 m of POF in full duplex mode.     

Plasmonic splitter based on the metal-insulator-metal waveguide with periodic grooves

In this paper, we have proposed a plasmonic splitter which is composed of a subwavelength slit and two different metal-insulator-metal (MIM) waveguides with periodic grooves. The slit is used to excite surface plasmon polaritons (SPPs) at certain wavelengths. By setting the SPPs resonance wavelengths of the slit as the Bragg wavelengths of MIM waveguides, the SPPs of different wavelengths are able to be confined and guided in the two different MIM waveguides. The numerical results of two-dimensional finite difference time domain (2D-FDTD) demonstrate that our proposed structure is capable of splitting light into two MIM waveguides.     

A low transmission loss THz polarization splitter based on dual-core optical fiber

We propose a design of a low loss terahertz polarization splitter based on a dual-core terahertz fiber with crossed dielectric strips in the fiber cross section. Low transmission loss is realized by extending the mode field to the air holes adjacent to the solid material. An 11.4-cm-long terahertz polarization splitter is obtained with the extinction ratio better than −15 dB and a bandwidth of 16 μm.     

Surface structure monitoring with plastic optical fiber

A sensor was designed using a plastic optical fiber to study the potential of detecting structural deformities and corrosion of metallic surfaces, in particular for applications in constricted areas such as pipes. The principle of the sensor is based on the collection of scattered light reflected by the surface imperfections. Several types of metallic materials in various surface profiles and stages of corrosion have been studied. The sensor was able to determine the position of ridges on the surface and corroded regions in all cases evaluated in the study. A sensitivity of 100 mV/mm was detectable for proximity and a vertical resolution of 1 mm has been measured.     

Polymer/silica hybrid waveguide Y-branch power splitter with loss compensation based on NaYF_4:Er~(3+), Yb~(3+) nanocrystals

A polymer waveguide Y-branch power splitter with loss compensation is proposed based on NaYF_4:Er~(3+), Yb~(3+)nanocrystals prepared by a high temperature thermal decomposition method. The Y-branch power splitter is designed as a structure of embedded waveguide, and its core material is nanocrystals-doped SU-8. The insertion loss of the device is ～ 15 dB. For an input signal power of 0.05 mW and a pump power of 267.7 mW, the two branches with 5.81-dB and5.41-dB loss compensations at 1530 nm are achieved respectively. A polymer waveguide Y-branch power splitter with loss compensation has an important research significance.     

Effect of plastic strain energy density on polymer optical fiber power losses

We explore the dependence of power losses on average plastic energy densities as rays propagate along deformed polymer optical fibers (POFs). The variation of power losses in deformed POFs with different bend radii and elongations are measured and analyzed. Three-dimensional elastic-plastic finite-element models are used to calculate average plastic energy densities in deformed POFs. The results indicate that the average plastic energy density introduced in a deformed POF can be considered a key index with which to study the power loss. Based on the experimental results, a curve-fitted equation is proposed for estimating the power loss by using the average plastic energy density for various bend radii.     

New type of Y-branch power splitter and beam expander based on eliminating anomalous reflection effect

We propose a new type of Y-branch power splitter and beam expander with scales of microns in two- dimensional （2D） photonic crystals （PCs） by drilling air holes in a silicon slice. Its functionality and performance are numerically investigated and simulated by finite-difference time-domain （FDTD） method. Simulation results show that the splitter can split a TE polarized light beam into two parallel sub-beams and the distance between them is tunable by changing the parameters of the splitter, while the expander can expand a narrow beam into a wider one, which is realized in an integrated optical circuit. The proposed device is based on the avoiding of anomalous reflection effect and the coupling transmission of defect modes of the interfaces.     

Two dimension photonic crystal Y-branch beam splitter with variation of splitting ratio based on hybrid defect controlled

This article represents a new Y-branch hybrid design of 2D photonic crystal with defect control. The structure is made of hexagonal arrays of InP nano-rods surrounded by air. This system is comprised of a modified add/change to a polymethylmethacrylate (PMMA) rod, which can be applied to the beam splitter selection device. The optical properties and radial of PMMA defect rods have been transfigured. By selecting an appropriate temperature, a change of refractive index and expanded radius are occurred. The obtained results have shown that the selected optical amplitude in a hybrid semiconductor-polymer Y-branch can be separated to 50–50, 60–40 and 67–33 % at wavelength 1.557 µm. Both of the photonic band gap and transmission spectra are calculated by using 2D finite different time domain (FDTD) method via OptiFDTD software. Such a device can be useful for photonic crystal switching devices in the integrated optical circuit.     

Three-dimensional polymer optical waveguide interleaver with selectable channel spacing

A polymer optical waveguide interleaver with selectable channel spacing and adjustable flat top based on a three-dimensional structure is reported. This interleaver is made of two waveguides laid in two different but parallel layers. These two waveguides cross-over each other three times, with an electrode heater deposited on top of each crossing point to adjust the coupling ratio between the guides. This 3D structure has many advantages over the corresponding 2D counterpart such as the ease of fabrication and the adjustment of coupling ratio between the two waveguides. The channel spacing can be selected to be either 1.6 nm, 0.8 nm or 0.53 nm simply by changing the power supplied to each heater; also at the 1.6 nm channel spacing it is possible to create a flat-top spectral response (0.6 dB ripple over 0.5 nm), again by tuning the coupling ratios using the electrical heaters.     

Temperature sensor based on etched optical fiber with a metal coating

Presented in this work is a new class of optical fiber temperature sensor, of which the heat-expansion thin film is coated on the etched fiber. It uses the method that combine thermal carving technique with chemical etching. The sensitivity of the sensor is increased and the shape size is decreased. This sensor possesses the linear temperature response and the good repeatability. These sensors can be used to measure finely the temperature which is lower than 200°c.     

Study on inverse taper based mode transformer for low loss coupling between silicon wire waveguide and lensed fiber

We have simulated the coupling loss of three types of Inverse Taper and taper-lensed fiber using three dimensional (3D) semi-vectorial beam propagation methods (BPM) respectively. Our results showed that the performances of exponential inverse taper and quadratic inverse taper were better than the commonly used linear inverse taper. Especially, for TM mode the improvement in the reduction of devices size is 53% and 136% for exponential and quadratic inverse taper compared with the linear inverse taper.     

Reconfigurable optical multiplexer based on liquid crystals for polymer optical fiber networks

In this work, different novel 3×1 multiplexer structures for being used in polymer optical fiber networks are proposed. Designs are compact, scalable, and of low consumption, capable of operating in a large wavelength range simultaneously 660, 850, and 1300 nm, due to the use of nematic liquid crystal cells. Light that comes from each input port is handled independently and eight operation modes are possible. Control electronics has been made using a programmable integrated circuit. Electronic system makes available the managing of the optical stage using a computer. An additional four optical sensors have been included for allowing the optical status checking. Finally, a polarization independent multiplexer has been implemented and tested. Insertion losses less than 4 dB and isolation better than 23 dB have been measured. In addition, 30-ms and 15-ms setup and rise times have been obtained. The proposed multiplexer can be used in any polymer optical fiber network, even in perfluorinated graded index one, and it can be specially useful in optical sensor networks, or in coarse wavelength division multiplexing networks.     

Compact and broadband waveguide taper based on partial bandgap photonic crystals

Partial bandgap characteristics of parallelogram lattice photonic crystals are proposed to suppress the radiation modes in a compact dielectric waveguide taper so as to obtain high transmittance in a large wavelength range. Band structure of the photonic crystals shows that there exists a partial bandgap, The photonie crystals with partial bandgap are then used as the cladding of a waveguide taper to reduce the radiation loss efficiently. In comparison with the conventional dielectric taper and the complete bandgap photonic crystal taper, the partial bandgap photonic crystal taper has a high transmittance of above 85% with a wide band of 170 nm.     

Oxygen gas optrode based on microstructured polymer optical fiber segment

In this article, we first propose a novel type of oxygen gas optrode by forming fluorophore doped sensing film in the array microholes with the characteristics of microstructured optical fiber (MOF) segment. Comparing with the conventional O₂ detecting method, this slender shaped optrode shows potential in trace amount of O₂ sensing and online O₂ monitoring. Organical silicate gel or plastified cellulose acetate are chosen as sensing films and tris (4,7-diphenyl-1,10-phenathroline) ruthenium(II) dichloride ([Ru(dpp)₃]Cl₂) or meso-tetraphenylporphyin (TPP) as quenching fluorophores. From the experimental results, we find [Ru(dpp)₃]²⁺-Gel-MOF optrode has favorable sensing characteristics, and the Stern-Volmer plots are linear in the full concentration range of O₂ (0-100% v/v). The ratio of I₀/I₁₀₀, where I₀ and I₁₀₀ respectively represents the fluorescence intensities of the optrode exposed to 100% N₂ and 100% O₂, as a sensitivity of the optrode is 10.8. Simultaneously, the optrode can make a quick response within 50 ms.     

Localized biosensing with Topas microstructured polymer optical fiber

We present what is believed to be the first microstructured polymer optical fiber (mPOF) fabricated from Topas cyclic olefin copolymer, which has attractive material and biochemical properties. This polymer allows for a novel type of fiber-optic biosensor, where localized sensor layers may be activated on the inner side of the air holes in a predetermined section of the mPOF. The concept is demonstrated using a fluorescence-based method for selective detection of fluorophore-labeled antibodies.     

Multi-hole plastic optical fiber force sensor based on femtosecond laser micromachining

We study the theoretical and experimental effects of hole quantity and inter–inter-hole spacing on insertion loss for using femtosecond laser to make bend-sensitive multi-hole plastic optical fiber(POF), and also analyze the mechanism of bending loss in multi-hole POF. A force sensor based on bending loss of the multi-hole POF is fabricated. The measurement ranges from 0 to 65 N, and the maximum output change exceeds 15.51 dB with good linearity and repeatability, and the sensitivity is 0.24 dB/N.     

塑料光纤直径测量系统

提出了以可编程逻辑器件为核心的塑料光纤直径在线测量系统,阐述了其工作原理。系统使用发光二极管作为光源、高精度线阵CCD作为图像传感器,简化了光学部分;应用EPLD和双口RAM,提高了信号处理效率;设计了提高测量精度的单片机数据处理算法。实验表明系统的测量范围为0 26～3mm,测量精度在10μm以内,满足塑料光纤直径测量要求。