1.

Introduction

Photonics technology currently drives major technical advancement in a wide diversity of technologies such as telecommunications, measurement science, industrial and environmental sensing, medical diagnostics and bio-sciences. In particular, the world’s main trunk telecommunications systems, the global internet and mobile phone communications systems are all founded on Photonics networks. Companies operating in these fields have an ever increasing demand for highly skilled scientists and engineers who can design, build, analyse, install and operate photonics systems. There is no doubt that the learning experience of these professional technologists is greatly enhanced during their graduate or undergraduate studies by exposure to hands on, practical experience of photonics components and systems. OptoSci Ltd, in collaboration with academics at Strathclyde and Heriot-Watt Universities, has developed a suite of Photonics Educator Kits which enable students to experimentally investigate all of the major technical features, principles and design issues of optical waveguides, optical communications systems, optical networks and OTDR, erbium doped fibre amplifiers and lasers. These application oriented kits are also supported by a range of experiments examining the fundamentals of physical optics, covering reflection, refraction, polarisation, diffraction, coherence and interference. In the development of all of these systems we adhere to a strict design philosophy and procedure, which ensures that all of the important educational objectives are met.

2.

Design Philosophy

The overall educational aims of the experimental exercises are to enable students to consolidate their understanding and knowledge of photonics as presented in an accompanying lecture course and to acquire practical experience of the design, analysis and characteristics of photonics components and systems. To achieve these aims it is essential to take a fully integrated approach to the design of laboratory based photonics teaching packages including the design of dedicated hardware, experimental procedures, exercises and manuals. To ensure that all desirable educational objectives are met and that all of the most important scientific and technical principles, issues and phenomena are addressed, we have developed our suite of fully integrated laboratory based teaching packages in accordance with the following design rules:

The primary constraint is cost and the final packages must be affordable within higher education budgets. In general, the packages have been designed as far as possible to be self-contained so that as little ancillary equipment as possible is required. However, where it is advantageous and cost effective to use equipment normally available in student laboratories, the packages have been designed to be compatible with the capabilities of such equipment e.g. a 20MHz or 50MHz oscilloscopes.

3.

Photonics Educator Kits

Using the design principles referred to above, OptoSci has commercially developed a unique range of fully self-contained laboratory based teaching packages for use in universities, colleges, and industrial training centres. The current series of educator kits allow students to perform detailed experimental investigations of the following topics:

Figure 1:

An educator kit at work!

The kits are designed in conjunction with senior academics from the internationally renowned optoelectronics teaching and research groups at Strathclyde and Heriot-Watt Universities to ensure high quality products that are directly relevant to teaching or training courses in this technological field. Furthermore, each package is a fully self-contained unit, incorporating all of the components and optoelectronic instruments required to perform the experiments thus allowing each kit to be immediately installed in the teaching laboratory. In addition, each educator kit is supplied with extensive literature support for the tutor and student. This includes, student manuals which describe the relevant background theory and experimental procedures; instructor’s manual with sample results for all experiments and exercises; detailed lecture notes with case studies and design exercises, and a series of tutorial questions with solutions.

The table below summarises some of the features and benefits of this range of teaching packages

Table 1:

Features & Benefits of OptoSci’s Photonics Educator Kits

Based on the many benefits that our range of photonics educator kits offer and the very positive feedback we have obtained from students and lecturers alike, we believe that these innovative products offer the tutor an immediate and cost effective solution to the provision of comprehensive and stimulating experimental courses in key areas of optics, optoelectronics, and optical communications.

The following sections provide a summary of the key educational objectives for each of the teaching packages and then briefly describe the associated experimental programme used to achieve these aims. A more detailed description of some of the background theory, experimental hardware, results and analysis is provided in previous publications [1-3] and on the OptoSci website [4].

4.

Optical Waveguiding

Information transmission along an optical fibre is governed by the principles and characteristics of optical waveguiding. The simplest approach to introducing students to the concepts and properties of optical waveguides is to begin with the principles of total internal reflection and then address the ray model of firstly step index, and then graded index planar waveguides. To support lecture courses on these topics, the overall objectives of the Optical Waveguiding package are to enable students to experimentally investigate and consolidate their understanding and knowledge of:

Figure 2:

Optical waveguiding educator kit

To meet the educational objectives stated above the students carry out the following investigation:

5.

Fibre Optic Communications

Optical fibre information transmission links enable more information to be transmitted over greater distance than any other communications technology. Hence, they have all but completely replaced copper based systems as the primary choice for global and local telecommunications systems. The objectives of the Optical Communications experiments are to enable students to experimentally investigate and build upon their knowledge and conceptual understanding of, and their ability to interpret:

Figure 3:

Fibre optic communications educator kit

To achieve these objectives the students carry out the following investigations:

6.

Erbium Doped Fibre Amplifiers And Lasers

Direct optical amplification using erbium doped fibre amplifiers (EDFAs) is now preferred over optoelectronic repeaters as the primary means of restoring the signal power in long distance fibre optic links and branched networks. In addition, lasers (essentially optical oscillators) are simply optical amplifiers with positive feedback, again highlighting the importance of optical amplifiers in modern photonics systems. The objectives of the EDF optical amplifier and laser experiments are to enable students to investigate and become practically familiar with the principles and characteristics of optical amplifiers and lasers in general, and erbium doped fibre amplifiers and lasers in particular. To achieve these objectives the EDF amplifier and laser experiments enable:

Figure 4:

Erbium doped fibre amplifier educator kit

7.

Optical Network Analysis - OTDR

In optical fibre networks, signal losses occur in the fibre itself, at splices and connectors and in the excess loss mechanisms within components like couplers and wavelength division multiplexers. With the passage of time, faults, such as fibre breaks, may occur, and splices, connectors and components degrade, resulting in increasing transmission losses which jeopardise the system performance. Optical time domain reflectometry (OTDR) is the industry standard technique employed for measuring the loss characteristics of a fibre link or network, monitoring the network status and locating faults and degrading components. Hence the main objectives of the network analysis laboratory exercises are the investigation and practical familiarisation with:

Figure 5:

Optical network analysis - OTDR educator kit

The students carry out the following investigation in four stages to build up skills and knowledge towards the analysis of complex networks:

8.

Physical Optics

The Principles of Physical Optics educator kit addresses the fundamental properties of light and the principles of physical optics. It consists of four individual modules covering detailed experiments in polarisation, reflection and refraction, diffraction, interference and coherence. The objective of this suite of modules is to provide the grounding in some of the basic properties of light, which are then applied in some of the kits described previously.

The students carry out the following experiments

8.3

Diffraction

• • Investigation of near and far field diffraction patterns for apertures and slits of various dimensions (Fraunhofer and Fresnel diffraction).

• • Confirmation of the width of various known slits and apertures and determination of the width of unknown slits and apertures.

• • Experimental investigation of diffraction at a reflective grating, including the basic grating equation (confirmation of grating line density).

• • Multiple order diffraction, the Littrow configuration, grating resolution and resolving power as a function of incidence angle and diffraction order using two wavelengths.

• • Determination of the wavelength of a second laser.

• • Diffraction through a transmission grating and measurement of line spacing.

Figure 6:

Diffraction module

8.4

Interference And Coherence

• • Construction of a Michelson interferometer and investigation of its multiple and single fringe alignment configurations.

• • Assessment of the surface quality of three different optical elements inserted into one arm of the interferometer.

• • Calculation of the wedge angle for one of the elements.

• • Investigation of the coherence function of a Fabry-Perot cavity laser.

• • Examination of the coherence length of the Fabry-Perot cavity laser as the laser’s drive current is varied.

• • Determination of the coherence length of the laser and measurement of its cavity length.

Figure 7:

Interference & coherence module

9.

Conclusions

A suite of laboratory based experimental teaching packages has been developed for modern optics, photonics and optical communications courses. OptoSci’s innovative design philosophy ensures: that all of the desired educational objectives are realised; that all major technical issues are addressed; and that each complete package can be offered for a price which is realistic within academic budgets. The kits are suitable for both physics and engineering based courses since they address fundamental physical principles, key technical issues, component and system performance characteristics and design processes (many of which, such as dispersion in optical fibres, were hitherto precluded by cost from the teaching environment). Furthermore, since each educator kit is fully self-contained the tutor is provided with all of the experimental equipment and literature support to immediately establish a teaching laboratory in key areas of photonics technology, in addition to providing extensive teaching material for the associated lecture course. Ultimately then, the key benefit for the tutor is that each of these unique and comprehensive teaching packages saves two to three years of course, literature and hardware development effort.