The wavelength selectivity of the grating is also used for designing waveguide filters working under Bragg condition. This paper describes recent progress in semiconductor optical active devices for pho-tonic networks. An in-depth discussion of the route towards fully integrated silicon photonics is presented. An exact treatment of the modal characterisation in 2D waveguides is not possible, even in the simplest case of a symmetric rectangular channel waveguide. Silicon Photonics explains the concepts of the technology, taking the reader through the introductory principles, on to more complex building blocks of the optical circuit. In some cases, the vectorial nature of the electromagnetic waves can be simplified, and a scalar treatment of the optical waves is often enough for a reasonable description of the phenomena involved.
While the first one allows us to calculate the electromagnetic field in a rectangular channel waveguide with a homogeneous central core , with the latter we can obtain the optical 3. This effective index is defined by two integer numbers p and q, reflecting the pth and qth order solution of equations 3. The main advantage of silica over silicon-based photonic waveguides is the low price and the good optical quality of the silicon substrates, besides being a well-known material with a long tradition, and the experience developed from micro-electronic technology. It consists of solving the problem in one dimension, described by the x coordinate, in such a way that the other coordinate the y coordinate acts as a parameter. Each type of material has its own advantages and disadvantages, and the choice of a specific substrate depends on the particular application of the photonic device. In the upper part of Figure 5.
This book gives an authoritative summary of the latest research in this emerging field, covering key topics for readers from various disciplines with an interest in integrated photonics. Future optical networks have several critical requirements, including low energy consumption, high efficiency, greater bandwidth and flexibility, which must be addressed in a compact form factor. By simple manipulation, equation 5. These components are clearly a transition towards the devices used nowadays in modern communication systems based on optical fibres. With many illustrations, including some in color, this handbook provides an up-to-date reference to the broad and rapidly changing area of silicon photonics. I would like also to thank Professor I. This is the demonstration of the fully potentiality of silicon photonics.
The state of the art of quasi phase matched integrated optical parametric generators and oscillators is reviewed. As we have discussed earlier, in this case we are dealing with an inhomogeneous wave, where its planes of equal amplitude and equal phase are perpendicular. With contributions from world experts, this reference guides readers through fundamental principles and focuses on crucial advances in making commercial use of silicon photonics a viable reality in the telecom and biomedical industries. The highest level of integration whether serial or parallel is achieved in monolithic integration, where all the optical elements including light sources, light control, electronics and detectors are incorporated in a single substrate. The structure consists initially of a symmetric planar waveguide in step, with a length of 200 µm, which splits into two branches of 550 µm length; from a distance of 750 µm the two branches become parallel.
For defining the optical circuits, a stopping mask is deposited onto the substrate, in such a way that the ionic exchange takes place only in the channels opened in the mask. The working principle of the coupler is based on the periodical optical power exchange that occurs between two adjacent waveguides through the overlapping of the evanescent waves of the propagating modes. Indeed, one of the most difficult tasks in packaging an integrated optical device is attaching the fibres to the chip waveguides, known as fibre pigtails. In this chapter we will introduce the main characteristics of integrated photonic technology, showing relevant aspects concerning material and fabrication technologies. One alternative to this dilemma consists in trying to implement realistic boundary conditions from a physical point of view, that is, an algorithm that allows the wave to leave the computational region when it reaches the window limits, without any reflection coming back to the domain.
In this way, radiation travelling in channel waveguides can propagate without suffering diffraction, that will otherwise give rise to power loss. Electro-optics deals with the study of optical devices in which the electrical interaction plays a relevant role in controlling the flow of light, such as electro-optic modulators, or certain types of lasers. The phase parameters ξ and η are calculated following equations 3. Therefore, in order to properly describe light propagation in a medium, whether vacuum or a material, it is necessary in general to know six scalar functions, with their dependence of the position and the time. One of the easiest and most intuitive solutions for this equation, and also the most frequently used in optics, is the plane wave. The simplest version of a power splitter is the Y-branch Figure 1. In the case of diffusion techniques it is possible to use photolithographic masks to define open channels through which the diffused material enters the substrate, or, alternatively, one can deposit the previously patterned material to be diffused directly onto the substrate.
Clearly, integrating multiple optical functions in a single photonic device is a key step towards lowering the costs of advanced optical systems, including optical communication networks. As a result of these new developments and associated with other technologies, such as electronics, new disciplines have appeared connected with optics: electro-optics, optoelectronics, quantum electronics, waveguide technology, etc. The most promising materials to achieve full monolithic integration are semiconductor materials, in particular GaAs and InP. The waveguide core with refractive index nf is embedded in a substrate of refractive index of ns being the upper part delimited by the cover with refractive index nc. Buried waveguides are fabricated by the refractive index increase of a substrate, in regions previously defined by appropriate photolithographic masks. Although the reflection and transmission coefficients give us valuable information concerning the relation between the electric field amplitudes of the incident, reflected and transmitted waves, in many cases the relevant parameter is the fraction of the incident energy that is reflected and transmitted at the interface, defined through reflectance and transmittance. Integrated optical circuits technology based on LiNbO3 substrates is now very well established, and a great variety of devices based on this technology, mainly in the field of optical communications, are now commercially available.
Besides this, the grating in integrated photonics can be used as an optical element for performing a wide range of functions such as focusing, deflection, coupling and decoupling light in the waveguide, feedback in an integrated laser, sensors, etc. Another way of building a waveguide reflector is 1. The last generation in optical systems concerns integrated photonics, and is based on optical circuits and components integrated in a single substrate. This element has two input ports and two output ports Figure 1. Small pieces of code are supplied where appropriate to get the reader started on the numeric work. Starting from a 2D waveguide, the problem is split into two step-index planar waveguides 3. Used textbooks do not come with supplemental materials.
In serial integration for optical communication devices the different elements of the optical chip are consecutively interconnected: laser and driver, modulator and driver electronics, and detector and receiver electronics. The so-called Helmholtz equation is indeed the starting equation for the analysis of optical waveguides. The most common geometries used for the definition of channel waveguides in integrated photonic devices are the stripe and the buried waveguides Figure 3. Professor Lifante has a broad teaching experience covering different teaching levels, including optics, optoelectronics and integrated photonics, and has directed several doctoral theses on integrated optics. It basically consists of a straight waveguide, which has rare earth ions incorporated to it, an undoped waveguide and a directional coupler. Silica channel waveguides are then formed by photolithographic pattern definition processes followed by reactive ion etching. Also, once one-dimensional waveguides are studied planar waveguides , we focus our attention on the theory of guided modes in two-dimensional structures such as channel waveguides, which are the basic elements in photonic integrated circuits.