Interacting with and Generating Light

Abstract

Table 32.1 lists some of the major terms, and their units, that we meet in this chapter. It also lists the important physical constants that are needed to describe the optical properties of materials. The electromagnetic spectrum embraces a wide range of wavelengths, from the very short γ rays to the long radio waves. The portion of the spectrum that the human eye can detect is quite small. To put this in context, the full electromagnetic spectrum is shown in Figure 32.1. Radiation with a single wavelength is referred to as monochromatic; λ and f are related through c.

$$ f = \frac{c}{\lambda } $$

1 People and History

Coble, R.L. (Bob) developed Lucalox^®, a transparent polycrystalline alumina (Al₂O₃) ceramic, at the GE Laboratory in Schenectady in 1961. GE is still a major supplier of lamp envelopes, but Silvania, Osram, and others also manufacture the envelopes now. (He was also interested in sintering).

Maxwell, James Clerk (1831–1879) developed the electromagnetic wave theory of light.

Seabright, Clarence A in the United States, was one of the key contributors to the development of ceramic pigments: (1948) Ceramic Pigments, U.S. Patent 2,441,367; (1961) Yellow Ceramic Pigments, U.S. Patent 3,012,898; (1965) Iron Ceramic Pigment, U.S. Patent 3,166,430.

van Royen, Willebrod Snell (1581–1626), the Dutch scientist who first described Snell’s law; the derivation is given in standard textbooks on electromagnetism (Panofsky and Philips 1961) or optics (Born and Wolf 1970).

2 Exercises

• 32.1 Why have we used this title for the chapter rather than calling it “Optics”?

• 32.2 Explain why BaTiO₃ is a linear electro-optic material below ${T_C}$ but a quadratic electro-optic material above ${T_C}$.

• 32.3 Polarized lead-lanthanum-zirconate-titanate (PLZT) ceramics belonging to either the tetragonal or rhombohedral crystal systems are classified as optically uniaxial. Which other crystal system or systems are also optically uniaxial?

• 32.4 Several methods have been used to produce PLZT thin films. Try to find as many methods as you can and discuss the pros and cons of each.

• 32.5 Prior to the development of transparent alumina ceramics, the material of choice for the lamp-envelope market was silica-based glass. Explain why such materials are not suitable for use in the sodium-vapor lamp but dominate the incandescent, fluorescent, and electric discharge lamp-envelope markets.

• 32.6 With the increasing demand for optical fiber communication systems, new glass and fiber processing methods are being investigated. One such example is the sol–gel route for silica fibers. What advantages do you think the sol–gel route would offer over the present chemical vapor deposition (CVD) processes? Can you think of any disadvantages of the sol–gel route?

• 32.7 The single crystals required for solid-state lasers are often made by the Czochralski process. Describe the advantages and disadvantages of using this process for producing single crystals of ruby and yttrium aluminum garnet (YAG).

• 32.8 Explain briefly why the transparency range of single-crystal NaCl is much greater than for single-crystal MgO.

• 32.9 Why are house bricks different colors? (You can answer this in 2 min or 2 h.)

• 32.10 How is the numerical aperture (NA) of a fiber linked to the NA of a camera lens?

• 32.11 What causes refraction in glass?

• 32.12 Did Beer and Lambert work together to come up with their law, and why are they linked to Bouguer?

• 32.13 “Refraction in ceramics is the most important phenomena in the development of biomedical engineering.” Discuss and criticize this statement.

• 32.14 Noncubic ceramics are birefringent. Explain why this is important for transparent polycrystalline alumina nose cones.

• 32.15 Discuss what the eye shown in Figure 32.27 and the lens in Figure 32.28 have in common and how you might use this idea in a new product.

• 32.16 The price of Ce-doped YAG is given in Section 32.15. How does this compare to the cost of commercial sapphire?

• 32.17 In Section 32.14 we get a bit carried away with PLZT-based devices. Are there environmental concerns with these materials? If so, what is being done to address them?

• 32.18 Is Si an electro-optic material? Discuss and reference your sources.

• 32.19 The topic of phosphors and emitters is dealt with very briefly but has enormous potential economic value. Explore the current literature and summarize the most active areas for research and development and how this relates to solid-state lighting.

• 32.20 We mention Nd-YAG lasers, but Nd is also used as a dopant in glass for laser applications. Explore why and what type of glass is used.