ebook img

Advances in Photonics for Information and Communication PDF

64 Pages·0.241 MB·English
Save to my drive
Quick download
Download
Most books are stored in the elastic cloud where traffic is expensive. For this reason, we have a limit on daily download.

Preview Advances in Photonics for Information and Communication

Advances in Photonics for Information and Communication Published by Pira International Ltd Cleeve Road, Leatherhead Surrey kt22 7ru UK T +44 (0) 1372 802080 F +44 (0) 1372 802079 E [email protected] W www.intertechpira.com The facts set out in this publication Pira International Ltd acknowledges product, service and company names referred to are obtained from sources which we in this report, many of which are trade names, service marks, trademarks or registered believe to be reliable. However, we trademarks. accept no legal liability of any kind for the publication contents, nor any information contained therein nor conclusions drawn by any party from it. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise without the prior permission of the Copyright owner. ISBN 1 85802 552 4 © Copyright Pira International Ltd 2007 Head of publications and events Philip Swinden [email protected] Publisher Rav Lally [email protected] Head of editorial Adam Page [email protected] Global editor Nick Waite [email protected] Head of US publishing Charles E. Spear, Jr. [email protected] Assistant editor Claire Jones [email protected] Customer services manager Denise Davidson [email protected] T +44 (0)1372 802080 Typeset in the UK by Jeff Porter, Deeping St James, Peterborough, Lincs [email protected] Contents List of tables v Applications 12 List of figures vi Fibre Bragg gratings 12 Executive summary vii Functionality 12 1 Types 13 Holey fibres 13 Properties 13 Features 13 Introduction 1 Types 14 Objective 1 Applications 14 Scope 1 Infrared emitters 14 Definitions 1 Properties 14 2 Waveguides 14 Optical waveguides 15 Tunable solid-state lasers 17 Types 17 Photonic materials and devices 5 Quantum cascade lasers 17 III–V semiconductors 5 Advantages 18 Properties 5 Disadvantages 18 Technical trends 5 Applications 18 II–VI semiconductors 6 Microstructured optical fibres 18 Properties 6 Technical trends 19 Technical trends 6 Properties 19 Rare earth elements 6 Applications 19 Properties 6 3 Technical trends 7 Photonic crystals 7 Properties 7 Technical trends 7 Photonics manufacturing 21 Applications 8 Plasma processing 21 Silicon-on-insulator 8 Reactive ion etching 21 Thick and thin 8 PECVD 21 Fabrication 8 Photolithography 21 Technical trends 9 Trends in lithography 22 Polymers 9 EB lithography 22 Properties 9 Microdrilling 22 Technical trends 9 Percussion laser drilling 22 Quantum dots 10 Trepanning laser drilling 23 Properties 10 Laser cutting 23 Fabrication 10 Polishing 23 Applications 11 In situ process monitoring 24 SiGe heterostructures 11 Laser deposition 24 Technical trends 12 LAMBD 25 Features 12 LCVD 26 Page iii © Copyright Pira International Ltd 2007 Advances in Photonics for Information and Communication Contents 4 Market forecast 34 Blue lasers 34 Multimedia services 34 5 Photonics in information and communication 27 CCD sensors 27 Materials 27 Future outlook and trends Parameters 27 in photonics 37 Types 27 Outlook for higher bandwidth 37 Applications 27 Outlook for optical switches 37 Next-generation CCDs 27 Outlook for WDM 37 Fibre-optic communications 28 DWDM 38 ATM 28 CWDM 38 Ethernet 29 Trends in photonic crystals 39 FDDI 29 Trends in quantum dots 39 SONET 30 Trends in QC lasers 40 Optical LANs 30 Trends in semiconductors 40 10Gb ethernet 30 Trends in metamaterials 40 Multimode fibre 32 6 Metropolitan area networks 32 Materials and devices 32 Protocols 32 Optical switching 33 Leading photonics suppliers and MEMS 33 users 41 Thermo-optical switches 34 Suppliers 41 Hybrid switches 34 Users 49 Page iv © Copyright Pira International Ltd 2007 List of tables 2.1 Fibre Bragg gratings 13 2.2 Tunable solid-state lasers 17 Page v © Copyright Pira International Ltd 2007 List of figures 2.1 Photonic crystal fibre 16 5.1 Wavelength division multiplexing 38 2.2 Quantum cascade laser 18 3.1 L aser-assisted molecular beam deposition 25 Page vi © Copyright Pira International Ltd 2007 Executive summary Information and communications technology encompasses an impressive range of subjects and an extraordinary range of applications. Photonics has revolutionised communication and the information processing industry. It includes optical communications, e.g. fibre optics, lasers and infrared links, optical imaging, e.g. charge-coupled devices (CCDs), optical data storage and optical computing and lasers. Photonics for The growth and development in information and communication systems for a faster information and and more efficient means of collecting and transferring information has led to the use communication of photonic technologies to meet the demands of modern high-speed communications. Photonics, an integral aspect of information technology, covers the whole of optics and electronics, and presents technology and infrastructure for the global internet and mobile communications. The objective is high bandwidth over long distances with minimal losses, and fibre optics is the most promising way to achieve this. A fibre-optic system is similar to the copper wire system that fibre optics is replacing. It is usually composed of a bundle of glass or plastic threads that sends information as modulated light. Technologies such as wavelength division multiplexing (WDM) and optical time division multiplexing (OTDM) further enhance a fibre’s bandwidth. Lasers are often used for information storage. A laser is used to record high-density information ranging from megabytes to gigabytes in CDs and DVDs. Fibre-optic systems use light-emitting diodes (LEDs) as light sources. LEDs are semiconductors that convert electrical current into light. They are small, reliable and last a long time. To transmit information, the light emitted from lasers and LEDs has to be modulated using optical modulators that vary the amplitude of the incoming signal. They can be used in computers to encode a high-quality data signal onto an optical beam, by turning the beam on and off to produce 1s and 0s. There has been a tremendous increase in the capability and quantity of photonic components. There is a trend towards smaller gadgets. This sudden revolution has been made possible by new photonic materials that will be used in future applications such as colossal data storage and high-rate data transfer. The new generation of III–V and II–VI semiconductors can be operated over a broad wavelength spectrum. Organic semiconductors, mostly consisting of carbon, hydrogen and oxygen, have contributed to huge strides in photonic components. Organic materials such as polymers are used to produce organic LEDs (OLEDs). Quantum dot LEDs can also be used in high-capacity data storage and optical memories. Fibre optics and large-area substrates are helping to realise broadband networks where there is high-bandwidth interconnection of many different components. Silicon photonics and other communications advances will drive future networks, servers and computers. By integrating photonics with silicon, different types of devices can be fabricated on a single chip, reducing the cost and increasing the number of applications. The key challenges include manufacturing, assembly and material properties. Page vii © Copyright Pira International Ltd 2007 Advances in Photonics for Information and Communication Executive summary Photonic materials Photonic materials are III–V, II–VI and rare earth semiconductor compounds, photonic and devices crystals, silicon oxynitride, silicon-on-insulator, polymers, quantum dots and wells, and silicon germanium (SiGe) heterostructures. III–V and II–VI III–V and II–VI semiconductors are made by combining elements from groups III and V semiconductors of the periodic table and groups II and VI of the periodic table. These materials have excellent light emission and absorption properties (optoelectronic properties) as well as high carrier mobility properties. Advances in crystal growth technology for III–V heterostructures have led to the fabrication of lattice-mismatched structures of gallium arsenide and indium phosphide. This enables the photonic devices and materials to be integrated for improved functionality. New techniques such as hydride vapour phase epitaxy (HVPE) are being developed to grow III–V structures on silicon. This makes it possible to integrate these structures with the silicon-based waveguide. II–VI compounds are grown by various techniques such as vapour phase epitaxy, chemical vapour deposition (CVD) and metallorganic vapour phase epitaxy (MOVPE). II–VI materials are increasingly being used to make nanocrystals as they have strong magneto-optical properties. Rare earth elements Rare earth elements are the 15 elements between lanthanum and hafnium in the periodic table. They are crucial in many technological applications. All have similar chemical properties and they emit light in an extremely narrow band. Rare earth doped fibres have gained popularity due to their advantages such as short device length, high power compatibility and low non-linearity. These fibres are double-cladding fibres typically inserted in a cavity and optical pumps to provide energy. Photonic crystals Photonic crystals are dielectric structures that are periodic in nature. Also known as metallodielectric nanostructures, they are designed to obstruct the propagation of electromagnetic waves. Optical micro- and nanocavities can be created by designing defects such as dislocations and holes into photonic crystals. Silicon-on-insulator Silicon-on-insulator (SOI) is a semiconductor manufacturing technology in which thin films of single-crystalline silicon are grown over an electrically insulating substrate. SOI improves electrical performance by reducing parasitic capacitance, especially in high- speed and very dense circuits. Quantum dots A quantum dot is a semiconductor nanostructure that confines the motion of conduction band electrons and excitons in all three spatial directions. The electrons and excitons are confined by an electrostatic field created at an interface between different semiconductor materials. An exciton is a bound electron–hole pair. Page viii © Copyright Pira International Ltd 2007 Advances in Photonics for Information and Communication Executive summary SiGe heterostructures Silicon germanium (SiGe) now has a small but significant percentage of manufactured semiconductor devices, and its share is predicted to rise substantially when SiGe begins to be used in CMOS technology to increase performance. The photonic devices comprise fibre Bragg gratings, holey fibres, infrared emitters, waveguides, tunable solid-state lasers, quantum cascade lasers and microstructured optical fibres. Fibre Bragg gratings A fibre Bragg grating is a periodic or constant perturbation of the effective refractive and 2D structures index in the core of an optical fibre. Holey fibres Holey fibres have a solid core and light is guided by a modified form of total internal reflection as air holes in the cladding lower the effective refractive index of the cladding relative to that of the solid core. In a photonic band gap fibre, the cladding air holes are arranged in a perfectly periodic fashion. For certain geometries the cladding can form a two-dimensional photonic crystal with band gaps at well-defined optical frequencies. Wavelengths within the band gap cannot propagate in the cladding and are confined to the core. Moreover, the core can have a lower refractive index than the cladding; it can even be air. Infrared emitters Different types of infrared emitters are used for different applications. Information and communications applications commonly use infrared LEDs. Infrared communication is useful for indoor use in areas of high population density. It does not penetrate walls, so it does not interfere with other devices in adjoining rooms. Infrared is the most common method for remote control. Waveguides A waveguide is a medium that guides and confines waves such as light and sound. The waveguides used in photonics are optical waveguides (communication) and planar waveguides (integrated photonics). Tunable solid-state Solid-state lasers are lasers whose lasing material is distributed in solid media or material lasers such as a solid rod or a slab of crystalline insulator. Some examples are Ti:sapphire, Cr: alexandrite lasers and Cr:LiSAF. Quantum cascade Quantum cascade lasers are a new generation of miniature lasers covering the whole lasers mid-infrared spectral region. They are based on inter-subband transitions of electrons inside a quantum well structure. These quantum wells are generally layers of gallium and aluminium compounds in which the optical transitions occur between electronic subbands created by quantum confinement in thin alternating layers of semiconductor materials. Microstructured Optical fibres are glass or plastic fibres that have the ability to guide light along their axis. optical fibres The fibre cable consists of three layers: core, cladding and jacket. Microstructured optical fibres (MOFs) contain air holes that run along their length and alter the waveguiding Page ix © Copyright Pira International Ltd 2007 Advances in Photonics for Information and Communication Executive summary properties. They are also known as index-guiding holey fibres (HFs) or photonic band gap fibres (PBGFs). MOFs offer immense flexibility in fibre design, and the large refractive index contrast between glass and air makes it possible to produce wavelength-scale features that offer a range of interesting properties. Photonics Photonic materials and devices are manufactured by laser-based diffusion, microdrilling manufacturing and microcutting, plasma and electron beam (EB) processes, and reactive ion etching. Other important processes are polishing, patterning and lithography. Polishing smoothes and shines the substrate. Most polishing is done chemically. Chemimechanical polishing (CMP) is widely used in the fabrication of ICs and semiconductor materials. It uses a slurry of colloidal silica (SiO ) suspended in potassium hydroxide (KOH) or some other 2 solution. Lithography is printing or creating patterns on a substrate; it is the main method of making microchips, where it is known as photolithography or optical lithography. A pattern is transferred from a photomask or reticle to the substrate surface. In situ process monitoring is a way to monitor and control semiconductor fabrication techniques, such as chemical vapour deposition (CVD). There is a need to monitor the chemical kinetics of the fabrication processes. For example, there is a need to measure the concentrations and physical distributions of the chemical species in a CVD chamber, especially at the interface between the wafer and the vapour. New process monitoring used in filter fabrication will drive up yields and cut costs considerably. Optical monitoring gives higher yields of thin films. Laser chemical vapour deposition (LCVD) uses a laser to heat selected areas of a substrate for fine control of CVD. Laser-assisted molecular beam deposition (LAMBD) uses a high-power laser beam to evaporate a target inside an ultrahigh vacuum (UHV) chamber; the target atoms or molecules are then deposited on a substrate. Microdrilling removes materials to create through holes. Lasers are commonly used for microdrilling photonic materials. Focusing beams or mirrors can be used to create the desired hole shape. Two types of drilling are used: percussion drilling and trepanning. Lasers are commonly used for microcutting photonic materials, usually a high-power pulsed laser such as a carbon dioxide (CO ) laser, water-guided laser or high-power fibre laser. 2 Plasma etching and plasma deposition are the most widely used processes in semiconductor fabrication. Plasma etching shoots a high-speed stream of plasma at the metal. Plasma-enhanced CVD (PECVD) is commonly used in microfabrication to deposit layers of insulating materials and amorphous silicon. It is used in very large scale integration (VLSI) and to make thin film transistors (TFTs). Reactive ion etching (RIE) uses plasma to etch material deposited on wafers. Deep RIE (DRIE) is a highly anisotropic process used to fabricate microelectromechanical systems (MEMS) plus 2D and 3D photonic crystals. Electron beams are generated in a high-vacuum environment from an electron gun. The photonics industry uses electron beams for lithography, drilling and cutting. EB lithography is used for pattern transfer. Page x © Copyright Pira International Ltd 2007

See more

The list of books you might like

Most books are stored in the elastic cloud where traffic is expensive. For this reason, we have a limit on daily download.