7: Lamps, LEDs, and Lasers
- Page ID
- 18984
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)Chapter 6 discussed devices that convert light to electricity. In this chapter, we discuss devices that convert electricity to light. These devices vary widely in size and shape from tiny Light Emitting Diodes (LEDs) and semiconductor lasers to large high power gas lasers. In addition to LEDs and lasers, lamps and optical amplifiers are also discussed.
We take lamps for granted now because they are present in practically all buildings. However, their invention dramatically improved human productivity because lamps allowed people to constructively use indoor spaces at night. Similarly, lasers have improved productivity in many activities. We encounter them almost daily in our use of communications networks, DVD players, medical devices, and in other applications.
- 7.1: Absorption, Spontaneous Emission, Stimulated Emission
- This page covers interconnected energy conversion processes: absorption, spontaneous emission, and stimulated emission, crucial for technologies such as solar cells and lasers. It details electron energy transitions, emphasizing the role of Einstein coefficients in understanding these dynamics and the importance of population inversion for optical amplification.
- 7.2: Devices Involving Spontaneous Emission
- This page covers three devices that produce light through spontaneous emission: incandescent lamps, gas discharge lamps, and LEDs. Incandescent lamps are inefficient due to heat loss, while gas discharge lamps vary in optical properties based on the gas used. LEDs are more efficient, with low voltage needs and longer lifespans, although they offer lower optical output compared to incandescent lamps. Organic LEDs (OLEDs) use organic materials for light emission.
- 7.3: Devices Involving Stimulated Emission
- This page covers the fundamentals of lasers, including their operation through stimulated emission, core components, and modes of operation. It explores the relationship between cavity length and photon stimulation, the efficiency of lasers, and their narrow bandwidth, beneficial for applications like optical communication. Various laser types are detailed, such as gas, dye, solid-state, and semiconductor lasers, each with unique characteristics and applications.
- 7.4: Relationship Between Devices
- This page examines devices that convert electricity and light, categorizing them by their operational processes: absorption, spontaneous emission, or stimulated emission. Illustrative figures clarify these classifications and the active materials involved. While many devices are specialized, some can function across multiple processes, exemplified by semiconductor lasers, which can act as LEDs or photodetectors.
- 7.5: Problems
- This page discusses lasers, including their emissions (spontaneous, stimulated, absorption), blackbody radiation, and semiconductor dimensions. It explains energy level calculations in gas lasers, the link between material composition and emitted wavelengths, and models laser spectra using Lorentzian functions. The page features practical software assignments for analysis, outlines essential laser components and types, and addresses safety concerns related to laser intensities.
Thumbnail: Six commercial lasers in operation, showing the range of different colored light beams that can be produced, from red to violet. From the top, the wavelengths of light are: 660 nm, 635 nm, 532 nm, 520 nm, 445 nm, and 405 nm. Manufactured by Q-line. (CC BY-SA 3.0 Unported; Sariling gawa via Wikipedia)