"Introduction". In: Fiber-Optic Communication Systems
82 CHAPTER 3. OPTICAL TRANSMITTERS (a) (b) Figure 3.3: Energy-band diagram of (a) homostructure and (b) double-heterostructurep– ...
3.1. BASIC CONCEPTS 83 Figure 3.4: Simultaneous confinement of charge carriers and optical field in a double- heterostructure de ...
84 CHAPTER 3. OPTICAL TRANSMITTERS rate, andRtot≡Rrr+Rnris the total recombination rate. It is customary to introduce the recomb ...
3.1. BASIC CONCEPTS 85 Figure 3.5: Lattice constants and bandgap energies of ternary and quaternary compounds formed by using ni ...
86 CHAPTER 3. OPTICAL TRANSMITTERS bandgap is not necessarily direct for such semiconductors. The shaded area in Fig. 3.5 repres ...
3.2. LIGHT-EMITTING DIODES 87 the laser performance. Suchquantum-well lasershave been studied extensively [14]. Often, multiple ...
88 CHAPTER 3. OPTICAL TRANSMITTERS Figure 3.6: Total internal reflection at the output facet of an LED. Only light emitted withi ...
3.2. LIGHT-EMITTING DIODES 89 Figure 3.7: (a) Power–current curves at several temperatures; (b) spectrum of the emitted light fo ...
90 CHAPTER 3. OPTICAL TRANSMITTERS injection [5]. The result is Rspon(ω)=A 0 ( ̄hω−Eg)^1 /^2 exp[−(h ̄ω−Eg)/kBT], (3.2.7) whereA ...
3.2. LIGHT-EMITTING DIODES 91 Figure 3.8: Schematic of a surface-emitting LED with a double-heterostructure geometry. In analogy ...
92 CHAPTER 3. OPTICAL TRANSMITTERS etching a well and bringing the fiber close to the emissive area. The power coupled into the ...
3.3. SEMICONDUCTOR LASERS 93 fibers. A relatively narrow spectral width of emitted light allows operation at high bit rates (∼10 ...
94 CHAPTER 3. OPTICAL TRANSMITTERS Figure 3.9: (a) Gain spectrum of a 1.3-μm InGaAsP laser at several carrier densitiesN. (b) Va ...
3.3. SEMICONDUCTOR LASERS 95 Figure 3.10: Structure of a semiconductor laser and the Fabry–Perot cavity associated with it. The ...
96 CHAPTER 3. OPTICAL TRANSMITTERS Figure 3.11: Gain and loss profiles in semiconductor lasers. Vertical bars show the location ...
3.3. SEMICONDUCTOR LASERS 97 Figure 3.12: A broad-area semiconductor laser. The active layer (hatched region) is sandwiched betw ...
98 CHAPTER 3. OPTICAL TRANSMITTERS Figure 3.13: Cross section of two stripe-geometry laser structures used to design gain-guided ...
3.4. CONTROL OF LONGITUDINAL MODES 99 Figure 3.14: Cross section of two index-guided semiconductor lasers: (a) ridge-waveguide s ...
100 CHAPTER 3. OPTICAL TRANSMITTERS L Figure 3.15: Gain and loss profiles for semiconductor lasers oscillating predominantly in ...
3.4. CONTROL OF LONGITUDINAL MODES 101 Figure 3.16: DFB and DBR laser structures. The shaded area shows the active region and th ...
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