2017-10-31
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Electronic Engineering
SPECIALIST READING A: Optoelectronics
9. Read the text. 5 parts have been removed from the text. Complete the text by matching the removed parts 1 – 5 with the gaps a) – e). There is one extra part which you do not need to use.
1. While an unbound electron does not exhibit quantized energy levels, an electron bound in an atomic orbital has quantized values of angular momentum. The wave-particle duality of energy and matter and the uncertainty principle provide a unified view of the behavior of photons, electrons and other atomic-scale objects.
2. The LED is used in many applications where illuminated displays are needed on instruments and household appliances. Unlike LED displays, LCDs just reflect or scatter light, but do not produce it themselves, so they cannot be seen in the dark.
3. It departs from classical mechanics primarily at the atomic and subatomic scales, the so-called quantum realm.
4. An actuator accepts energy and produces movement. The energy supplied to an actuator might be electrical or mechanical.
5. The science of photonics includes the generation, emission, transmission, modulation, signal processing, switching, amplification, detection and sensing of light.
6. Like radio waves and microwaves, light is a form of electromagnetic radiation, but its wavelength is very short. Photodetectors allow light to irradiate a semiconductor that absorbs the light as photons and converts these to electric signals.
Optical electronics or optoelectronics is the study and application of electronic devices that source, detect and control light. Optoelectronics is usually considered a sub-field of photonics. a) ____. The term photonics thereby emphasizes that photons are neither particles nor waves — they are different in that they have both particle and wave nature.
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Optoelectronics is based on the quantum mechanical effects of light on semiconducting materials, sometimes in the presence of electric fields. Quantum mechanics, also known as quantum physics or quantum theory, is a branch of physics providing a mathematical description of the dual particle-like and wave-like behavior and interactions of energy and matter. b) ____. The name, coined by Max Planck, derives from the observation that some physical quantities can be changed only by discrete amounts, or quanta, as multiples of the Planck constant, rather than being capable of varying continuously or by any arbitrary amount. For example, the angular momentum, or more generally the action, of an electron bound into an atom or molecule is quantized. c) ___.
Optical electronics covers all technical applications of light over the whole spectrum from ultraviolet over the visible to the near-, mid- and far-infrared. Most applications, however, are in therange of the visible and near infrared light. In this context, light often includes invisible forms of radiation such as gamma rays, X-rays, ultraviolet and infrared, in addition to visible light.
Optoelectronic devices are electrical-to-optical or optical-to-electrical transducers, or instruments that use such devices in their operation. It involves combined applications of optical and electronic signals. The three key uses of optoelectronics are to detect light, to convert solar energy to electric energy, and to convert electric energy to light.
d) ___. Light meters, burglar alarms, and many industrial uses feature photodetectors. Solar cells convert light from the sun to electric energy. They use single-crystal doped silicon to reduce internal
