Optical Multimode Interference Research Articles

Low-cost optical fiber multimode interference biosensor based on a glucose sensitive Glucose-Oxidase enzyme thin-film.

Low-cost optical fiber multimode interference biosensor based on a glucose sensitive Glucose-Oxidase enzyme thin-film.

LeTrungThanh Optical Biosensors Based on Multimode Interference and Microring Resonator Structures

LeTrungThanh Optical Biosensors Based on Multimode Interference and Microring Resonator Structures

A novel reconfigurable radio-over-fiber system based on flexible optical devices

In this paper, a reconfigurable Radio over Fiber system based on optical switches, optical multimode interference power splitter and tunable optical filters is designed, which can achieve quadrature phase shift keying wireless modulation in optical domain and switch carrier frequency between 30 and 60 GHz. The scheme can make good use of bandwidth resource and realize signal transmission in fiber within 10 km.

Numerical analysis of selectively coated MMI structures for the application in optical sensor technology

In this work the numerical analysis of an optical sensor based on multimode interference structures with the sensing layer which cover selectively multimode waveguide are presented. The analyzed gradient index optical waveguides are fabricated in sodium-potassium ion exchange process. The effects of the different shape of the sensing layer and excitation conditions are demonstrated. Full Text: PDF References K.R. Kribich et al., "Novel chemical sensor/biosensor platform based on optical multimode interference (MMI) couplers", Sens. Actuat. B-Chem 107, 188 (2005). CrossRef T. Mazingue et al., "Simulations of refractive index variation in a multimode interference coupler: Application to gas sensing", Opt. Comm., 278(2), 312 (2007). CrossRef A. Szewczuk, M. Blahut, "Polarization effects in K+?Na+ ion exchanged MMI structures with absorption cover", Optica Applicata, 43, 441 (2013). CrossRef A. Szewczuk, M. Blahut, "MMI Structures Covered by Bromocresol Purple for Ammonia Detection", Acta. Phys. Pol. A 124, 570 (2013). CrossRef A. Szewczuk, M. Blahut, "Impact of high index buffer layer on the improvement of the MMI sensor sensitivity", Photonics Lett. Poland 6(4), 127 (2014). CrossRef

Experimental Analysis of Optical Fiber Multimode Interference Structure and its Application to Refractive Index Measurement

We investigated a fiber-based multimode interference phenomenon in the wavelength domain by using a white light source and an optical spectrum analyzer. This phenomenon was produced by a larger-core optical fiber joined at both ends with smaller-core optical fibers. We examined the variation of interference wavelength with changes in the length of the larger-core fiber. The interference wavelengths were blue-shifted and the interference signals were sharpened with an increase in the length of the larger-core fiber. The calculated results agreed well with the measured results. Next, we investigated how the input and output fibers with a small core influence the interference signal characteristics. By comparing the amplitude differences of the interference signal we find the conditions of input and output (I/O) fibers for higher sensitivity. In addition, an interference-signal shift was observed by changing the medium surrounding an multimode interference (MMI) structure. The amount of shift increased at a longer wavelength. This leads to the sensitive detection of the refractive index. Finally, a demonstration of the optical fiber refractometer with a multimode interference structure was given by refractive-index measurements of ethanol/water solutions.

Experimental Analysis of Optical Fiber Multimode Interference Structure and its Application to Refractive Index Measurement

Experimental Analysis of Optical Fiber Multimode Interference Structure and its Application to Refractive Index Measurement

Design of Optical Multimode Interference Couplers with Ultracompact Propagating Width

Abstract In this paper, to evaluate the design properties of 3D optical multimode interference (MMI) couplers with ultracompact width, modal transmission line theory and effective dielectric method are combined with together. A coupling efficiency based on the composed approach is defined, and the coupling length is numerically determined for the design of 3 dB coupler, cross coupler and bar coupler. The simulation result shows that the designed MMI coupler has a low insertion loss and a high splitting ratio.Key Words : MMI coupler, Power splitting, Equivalent network Ⅰ. 서 론 광 결합기는 광 집적소자를 구성하는 가장 기본적인 요소이다. 이 소자들은 광 신호 라우팅이나 광 신호처리를 위하여 필수적으로 사용하는 소자들이다 [1-3] . 오늘날 그 중에서도 다중모드 간섭 (Multimode Interference: MMI) 결합기들은 낮은 초과 손실 (Excess Loss), 높은 소멸 비 (Extinction Ratio), 작은 크기 그리고 제작 시에 발생하는 제작 허용오류 (Tolerance)에 대한 낮은 의존율에 기인하여 지속적으로 그 관심이 증가하고 있는 광 소자이다. MMI 결합기를 설계하기 위하여 제안된 1차원적 모델링 기법들은 이미 여러 차례 보고되어 왔다 [4] . 또한, 최근에 유한 요소법 (Finite Element Method)를 이용한 3차원적 모델링에 대한 설계법도 보고된바 있다 [5]

An Optical Phase-Locked Loop Photonic Integrated Circuit

We present the design, fabrication, and results from the first monolithically integrated optical phase-locked loop (OPLL) photonic integrated circuit (PIC) suitable for a variety of homodyne and offset phase locking applications. This InP-based PIC contains two sampled-grating distributed reflector (SG-DBR) lasers, semiconductor optical amplifiers (SOAs), phase modulators, balanced photodetectors, and multimode interference (MMI)-couplers and splitters. The SG-DBR lasers have more than 5 THz of frequency tuning range and can generate a coherent beat for a wide spectrum of frequencies. In addition, the SG-DBR lasers have large tuning sensitivities and do not exhibit any phase inversion over the frequency modulation bandwidths making them ideal for use as current controlled oscillators in feedback loops. These SG-DBR lasers have wide linewidths and require high feedback loop bandwidths in order to be used in OPLLs. This is made possible using photonic integration which provides low cost, easy to package compact loops with low feedback latencies. In this paper, we present two experiments to demonstrate proof-of-concept operation of the OPLL-PIC: homodyne locking and offset locking of the SG-DBR lasers.

Metal-oxide semiconductor, field effect transistor-based microscale electro-optical multimode interference modulator on a silicon chip

A new approach allows the realization of an electro-optical modulator or a transistor that is integrated on a silicon chip. The operation principle includes the realization of optical multimode interference (MMI) as the operation core of an electro-optical metal-oxide-semiconductor (MOS) field effect transistor (FET). Externally applied voltage generates a depletion region as well as layer of inversion which is full with free carriers. The free carriers vary the relative phase shift as well as the attenuation of one arm of the interferometer due to the plasma dispersion effect in silicon. This variation allows breaking the balance of the mode conversion and results with amplitude modulation in the output of the MMI region. The device does not have high finesse resonance and yet its overall length is only about 18 µm.

Novel chemical sensor/biosensor platform based on optical multimode interference (MMI) couplers

We present a novel platform for chemical sensing and biosensing. The working principle is based on the interference properties of an optical multimode interference coupler. A humidity sensor has been implemented as a proof of principle. It has been realised using hybrid sol–gel planar technology to allow integration on a silicon substrate. Firstly, we describe the theory of multimode interference and we model the sensor response to the change of the sensing layer refractive index. Then, the sensing material is described and characterised regarding optical and sensing properties. Finally, the prototype device is characterised. A linear response to relative humidity is obtained and it is shown that sensitivity can be tuned using the MMI design technique.

Photonics Devices Based on Hybrid Approach Combining Liquid Crystals and Sol-Gel Waveguides

ABSTRACT A number of integrated electro-optic devices based on hybrid technology combining liquid crystals and sol-gel waveguide are investigated. An integrated electro-optic switch, based on ferroelectric liquid crystal waveguides, is experimentally characterized. Moreover an electro-optical switch and a continuously tunable filter, based on a Bragg grating in planar waveguide with a liquid crystal overlayer, are numerically analyzed. Finally, an optical multimode interference router is theoretically and numerically discussed. The principal advantages of such devices include good performances, low power consumption, low cost and small device size.

Optical multimode interference router based on a liquid crystal waveguide

In this paper, for the first time, the performance of an electro-optical router, working at a wavelength of 1.55µm and based on multimode interference effects together with the electro-optic effect of smectic A liquid crystal, is theoretically and numerically discussed. The device comprises: a single-mode input optical channel waveguide, a bimodal active region with a liquid crystal over-layer, and an output Y-branch to separate the two output channels. The active region is designed to allow a π shift between the two modes that it supports, by means of the electro-optic effect of smectic A, in order to steer light from one output channel to the other. The principal advantages of such a device include a fast tuning speed, low power consumption, low cost and small device size.

Single-mode rib polymer waveguides and electro-optic polymer waveguide switches

Mode-matching and effective index methods are used to analyze single-mode operation of optical rib polymer waveguides. Their single-mode waveguiding conditions are determined. Single-mode rib waveguides fabricated from guest–host polyetherketone are presented. The estimated propagation loss of straight rib-waveguides is 0.7 dB/cm at 1.55 μm. Furthermore, by using the mode field-transfer matrix method, 2×2 and 4×4 polymer Mach–Zehnder interference switch operating at 1.55 μm wavelength has been designed based on optical multi-mode interference.

Optical Multimode Interference Router in Sol-gel Waveguide with a Liquid Crystal Cladding

The self-imaging principle has been applied in the design of a novel configuration for an electro-optical router, working at the wavelength of 1.55 micron. The device is composed by: a single mode input optical channel waveguide; a bimodal active region, having a liquid crystal as over-layer; an output Y branch, to separate the two output channels. The active region is designed to allow a π shift between the two modes that it supports, by means of electro-optic effect of smectic A*, in order to steer light from one output channel to the other one. In this paper, for the first time, the performances of an electro-optical router, based on the multimode interference effects together with the electro-optic effect of smectic A* liquid crystal, are theoretically and numerically discussed.

General matrix theory of self-imaging in multimode interference (MMI) couplers

We present a simple and very general matrix method for predicting the properties of integrated optical multimode interference (MMI) couplers with single-mode input and output guides. We derive a set of N/spl times/N matrices which (in the paraxial limit) can be used to predict the complex mode amplitudes in the output guides from the complex mode amplitudes in the input guides for any type of MMI coupler, splitter or recombiner. We compare this theory with experiment for an 11/spl times/11 nonuniform coupler.

Optical multi-mode interference devices based on self-imaging: principles and applications

This paper presents an overview of integrated optics routing and coupling devices based on multimode interference. The underlying self-imaging principle in multimode waveguides is described using a guided mode propagation analysis. Special issues concerning the design and operation of multimode interference devices are discussed, followed by a survey of reported applications. It is shown that multimode interference couplers offer superior performance, excellent tolerance to polarization and wavelength variations, and relaxed fabrication requirements when compared to alternatives such as directional couplers, adiabatic X- or Y-junctions, and diffractive star couplers. >

Extremely small multimode interference couplers and ultrashort bends on InP by deep etching

We realized the smallest integrated optical multimode interference (MMI) couplers to date by etching through the quaternary guiding layer, maximizing the lateral index contrast, and thus obtaining a sufficient number of guided modes for proper operation despite the small size. Results include a 107 μm long 3 dB coupler with 0.9 dB excess loss and 0.2 dB unbalance, and a 216 μm long cross coupler with 2.0 dB excess loss and -28 dB crosstalk (TE). We also succeeded in making waveguide bends with a record bending radius of only 30 μm and negligible radiation loss.