扩展多模波导全内反射型Y分叉开关的分析

利用全内反射和波导理论，分析了多模波导反射区全内反射(Total Internal Reflection，TIR)型光开关的物理模型和降低串音和损耗的原因，给出改进Y分叉全内反射型光开关特征的近似计算方法。数值模拟表明，扩展多模波导的Y分叉全内反射开关的串音和损耗可分别下降15．5dB和0．65dB以上。     

带有矩形过渡区的非对称Y分支光波导

提出了带有矩形过渡区的非对称Y分支光波导的两种设计方案。分别通过设置两分支波导不同的宽度和改变分支波导与矩形中心的轴偏移量,去获得非对称分支比。采用有限差分光束传播法（FD-BPM）对两种结构进行模拟,得出它们的分支比和损耗。分支比分别最高可达809／6和72．9％,其相对应的损耗分别低于0．12dB和0．23dB,充分证明了方案的可行性,为以后非对称Y分支光波导的制作提供了实验基础。     

特种非对称低损耗1×5光分路器

设计和优化了一种新型低损耗、低偏振的基于二氧化硅的特种非对称1×5光分路器.在设计Y分支结构时,输入端采用缓变展宽波导结构和直波导过渡波导相结合的结构,此结构可以使输入光场缓慢展宽,进行分束前的准备,大大减小分支结构的辐射损耗和模式转换损耗.非对称1×5光分路器第一个端口输出功率占50%,第二至五端口输出功率占50%.利用三维光束传播法模拟和优化了特种非对称1×5光分路器,模拟结果表明,该结构具有均匀性好、器件尺寸小、低损耗和低偏振等优点,1×5光分路器在1 250~1 650 nm波长范围内,第一个输出端口附加损耗小于0.07 dB,均匀性小于0.023 dB,偏振相关损耗小于0.009 dB,第二到五端口附加损耗小于0.45 dB,均匀性小于0.41 dB,偏振相关损耗小于0.06 dB.     

Fabrication of 1×2 asymmetric plastic optical fiber coupler for portable optical access-card system

We proposed a simple low-cost acrylic and metal-based Y-branch plastic optical fiber (POF) splitter which utilizes a low cost optical polymer glue NOA63 as the main waveguiding medium at the waveguide taper region. The device is composed of three sections: an input POF waveguide, a middle waveguide taper region and output POF waveguides. A desktop high speed CNC engraver is utilized to produce the mold inserts used for the optical devices. Short POF fibers are inserted into the engraved slots at the input and output ports. UV curable optical polymer glue NOA63 is injected into the waveguide taper region and cured. The assembling is completed when the top plate is positioned to enclose the device structure and connecting screws are secured. Both POF splitters have an average insertion loss of 7.8 dB, coupling ratio of 55: 45 and 57: 43 for the acrylic and metal-based splitters respectively. The devices have excess loss of 4.82 and 4.73 dB for the acrylic and metal-based splitters respectively.     

Acrylic and metal based Y-branch plastic optical fiber splitter with optical NOA63 polymer waveguide taper region

We proposed a simple low-cost acrylic and metal-based Y-branch plastic optical fiber (POF) splitter which utilizes a low cost optical polymer glue NOA63 as the main waveguiding medium at the waveguide taper region. The device is composed of three sections: an input POF waveguide, a middle waveguide taper region and output POF waveguides. A desktop high speed CNC engraver is utilized to produce the mold inserts used for the optical devices. Short POF fibers are inserted into the engraved slots at the input and output ports. UV curable optical polymer glue NOA63 is injected into the waveguide taper region and cured. The assembling is completed when the top plate is positioned to enclose the device structure and connecting screws are secured. Both POF splitters have an average insertion loss of 7.8 dB, coupling ratio of 55: 45 and 57: 43 for the acrylic and metal-based splitters respectively. The devices have excess loss of 4.82 and 4.73 dB for the acrylic and metal-based splitters respectively.     

Optimized design of a new three branch optical waveguide

A new type of 1 × 3 Y-branch optical waveguide structure with a cone transitional section is introduced in this paper. The symmetrical branch ratio of the 1 × 3 Y branch optical waveguide is obtained by changing the width of this waveguide. The loss and the uniformity are obtained by using the finite difference beam propagation methods, and their values are 0.2 dB and 0.05 dB, respectively. Therefore, it provides some experimental basis for production of three branch optical waveguide.     

Monolithically Integrated Transceiver with Novel Y-Branch by Bundle Integrated Waveguide for Fibre Optic Gyroscope

A novel Y-branch based monolithic transceiver with a superluminescent diode and a waveguide photodiode (Y-SDL-PD) is designed and fabricated by the method of bundle integrated waveguide (BIG) as the scheme for monolithic integration and angled Y-branch as the passive bi-directional waveguide. The simulations of BIG and Y-branches show low losses and improved far-field patterns, based on the beam propagation method (BPM). The amplified spontaneous emission of the device is up to 10mW at 120mA with no threshold and saturation. Spectral characteristics of about 30nm width and less than 1dB modulation are achieved using the built-in anti-lasing ability ofY-branch. The beam divergence angles in horizontal and vertical directions are optimized to as small as 12°× 8°, resulting in good fibre coupling.     

Active semiconductor optical switches with blue-shifted channel waveguides

This paper presents a theoretical design study of active optical switches constructed from III-V semiconductor multiple-quantum-well waveguides. New designs are given for 4 × 4 matrix switches, 1 × 4 tree switches, and 4-delay optical transversal filters. The designs feature ∼ 0 dB insertion loss and ∼ 30 dB crosstalk isolation. Low injection currents are predicted because pumping is eliminated on ∼ 70 percent of the channel waveguide area by an induced-disorder treatment that blue-shifts the material's absorption edge. The active networks also feature etched facet reflectors that facilitate the dense packing of guides.     

A novel Y-branch waveguide for power dividing and mode splitting

A novel Y-branch waveguide for variable-ratio power dividing and transverse electrical-transverse magnetic (TE-TM) mode splitting depending on the applied voltage is presented. The Y-branch waveguide is formed by two closely coupled waveguides tabricated by nickel indiffusion (NI) and by magnesium-oxide induced lithium outdiffusion (MILO) in a y-cut lithium niobate (LiNbO₃) substrate. The TE component of the randomly polarized light is tuned between these two waveguides, such that the device can be either a power divider or a mode splitter depending on the applied voltage. The measured TE mode extinction ratio is about 20 dB.     

A wide-band polymeric electro-optic modulator array based on unidirectional coupling between multi-mode waveguide array and a vertical configured dumping planar waveguide

A polymeric wide-band electro-optic (EO) modulator array based on unidirectional mode-coupling between the guiding multi-mode waveguide array and a vertical configured planar dumping waveguide was developed. A low insertion loss of <1.7 dB was obtained due to asymmetrically designed guiding waveguide and the dumping waveguide. A modulation depth of 91% was achieved with the device length of 3.5 cm at a low driving voltage of 3.2 V. The employment of the dumping planar waveguide not only provides an efficient way to achieve the unidirectional coupling mechanism, but also effectively confines the light coupled from the guiding waveguides within the planar dumping waveguide. The combination of unidirectional coupling and light confinement effects ensures low cross talk of <22 dB between adjacent guiding waveguides. Since the proposed modulator is based on the unidirectional coupling mechanism, it is intrinsically wide-band. A wide-band operation from 1308 to 1324 nm was experimentally obtained. The unidirectional mode-coupling-based wide-band modulation principle can be readily applied to other wavelengths, such as 1330 and 1550 nm ranges.     

基于表面等等离波子的新型Y分支波导

新型高效的纳米光波导器件的研制纳米集成光学的核心技术之一。Y分支波导作为最基本的分光和光路连接元件是纳米光学器件设计与制备的基础。运用时域有限差分(FDTD)法,模拟计算了基于表面等等离波子(SPP)的纳米Y分支波导的传输特性。结果表明,该新型Y分支波导在光通信波段可以实现大角度的分光功能,且在180°分支情况下,传输效率仍高达92.8%以上。另外,该波导还具有导波性能良好、对分叉处间隙缺陷大小不敏感及制作容差较大和器件尺寸在纳米量级等特点。对该新型光波导器件的研究为未来纳米集成光学器件的研制和应用有一定的指导意义。     

Polymer-silica hybrid 1 × 2 thermooptic switch with low crosstalk

A new polymer-silica hybrid 1 × 2 thermooptic switch with significantly low crosstalk is demonstrated. The top cladding and the core layers are composed of polymer, while the bottom cladding layer is made of silica. Since polymer and silica have algebraic signs of their thermooptic coefficients that are opposite to each other, the refractive index of the core changes in the opposite direction to that of the bottom cladding as the temperature is increased. Thus, switching operation is initially done through adiabatic mode evolution in the Y-branch, and then a heated waveguide arm in the Y-branch can enter into the optical cut-off region if the temperature is sufficiently high. Using this phenomenon, low crosstalk performance is achieved. The proposed device has a crosstalk of −35 dB, while most integrated-optic switches with a single stage have a relatively high crosstalk in the region of −20 dB. The switching power of the proposed device is about 70 mW.     

Design and fabrication of compact 3-dB coupler in silicon-on-insulator

A novel compact 3-dB coupler is proposed and fabricated in silicon-on-insulator. The new coupler provides large output waveguide spacing of 125.0 μm with short device length of 867.0 μm and large cross-section of 6.0 × 4.0 μm. The device length can be remained essentially unchanged even when the output spacing is further enlarged to realize the complex applications in photonic integrated circuits. The fabricated device exhibits excess loss of 6.3 dB and low imbalance of 0.26 dB.     

质子交换LiNbO3波导调制器多模截止波长的测试技术研究

提出并实验了一种采用倒置输入的结构来测定Y分支LiNbO3波导相位调制器的多模截止波长的新方法,模式耦合分析表明,倒置输入的Y分支波导的多模传输的输出功率具有随波长变动发生振荡的特征,该特征可用于定量判定多模截止波长.方法的有效性得到了波束传播法(BPM)仿真和样品实验两方面的验证.     

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.     

电光聚合物波导中的锥形结构

提出并设计了一种基于电光聚合物的锥形波导,可用于单模光纤与电光聚合物波导器件之间的连接.锥形波导中采用了宽度锥形和折射率锥形结构.宽度锥形采用劈形形状,通过宽度和折射率的缓慢变化实现模场转换.劈形形状的宽度锥形具有较小的损耗且易于制作,折射率锥形可采用灰度掩膜光刻技术制作.研究了锥形波导的传输损耗与锥形波导的长度、波导宽度和厚度、材料吸收损耗等参数的关系及其优化,分析了锥形波导中的功率传输、模场分布与模式转换效率.结果显示锥形波导的传输损耗小于0.37 dB,光纤-波导-光纤的连接损耗优于1.62 dB,对插入损耗的改善达到8.78 dB,模场转换效率达到了83.7%.     

基于光纤反射腔的高灵敏电流传感器方案

提出了一种基于平面Y分支波导与法拉第旋镜的高灵敏度光纤电流传感器结构方案。利用两个法拉第旋镜与平面Y分支波导构成一个光纤反射腔,通过光在腔中的多次反射来增加待测电流导致的传感光纤中的法拉第相移,从而实现对微弱电流的测量。该结构方案中首次采用了平面Y分支光波导,从而可降低光路系统损耗,增加灵敏度,为微弱电流测量的工程化提供了一种可行的方法。     

Optical coding scheme for all-optical analog-to-digital conversion using asymmetrical Y-branch waveguide

The novel optical coding scheme for all-optical analog-to-digital conversion has been proposed, in which asymmetrical Y-branch waveguide structures have been introduced to achieve the desired optical power splitting. The optical performance has been simulated by using finite-difference beam propagation method (FD-BPM), which shows that the designed component exhibits good coding performance. Experimentally, the optical coding component has been fabricated and measured. The optical power contrast between bit code 1 and 0 at output port is more than 37 dB, and measured imbalance of output power is less than 1.5 dB for bit code 1.     

Analytical modeling of loss characteristics of a polymer arrayed waveguide grating multiplexer

Theoretical analysis is performed for the loss characteristics of a polymer arrayed waveguide grating (AWG) multiplexer around the central wavelength of 1.55 μm with the wavelength spacing of 1.6 nm. The total loss of the device includes the diffraction loss in the input and output (I/O) slab waveguides, bent loss caused by the AWG and I/O channels, leakage loss resulted from the high refractive index substrate, and propagation loss due to the absorption and scattering of the materials of the device. The effects of some structural parameters on the loss characteristics are investigated and discussed. The computed results show that when we select the core thickness as 4 μm, core width as 6 μm, pitch of adjacent waveguides as 15.5 μm, diffraction order as 50, the number of the arrayed waveguides as 91, that of the I/O channels as 17, confined layer thickness between the core and the substrate as 10 μm, distance between the focal point and the origin as 5500 μm, and central angle between the central waveguide and the x-axis (i.e. the vertical of the symmetrical line of the device) as 60°, the total loss of the device can be dropped to the range 3.79–7.93 dB.     

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.