1. Yonsei Univ. High-Speed Information Transmission Lab. Lect. 3-4-(1) Optical Amplifier 2003. 5. 19 (Mon.) ● About “ Semiconductor ” Si : 4 족이므로, Valence electron 이 4 개 * 구조의 특징 : 단단하고 안정적이다. Si + …… 원자 수준에서는 discrete 한 energy level 이 결정이 되면, energy band 가 된다.

2. Yonsei Univ. High-Speed Information Transmission Lab. Lect. 3-4-(2) Optical Amplifier 2003. 5. 19 (Mon.) Conduction Band E k Valence Band Band Gap : At Conduction Band… At Valence Band… 의 관계에 따라서 Absorption, Spontaneous emission, Spontaneous emission 이 일어난다. Band Gap

3. Yonsei Univ. High-Speed Information Transmission Lab. Lect. 3-4-(3) Optical Amplifier 2003. 5. 19 (Mon.) The E-k diagram of a direct bandgap semiconductor such as GaAs. The E-k curve consists of many discrete points with each point corresponding to a possible state, wavefunction on, that is allowed to exist in the crystal. The points are so close that we normally draw the E-k relationship as a continuous curve. In the energy range to there are no points ( solutions). E k 절대온도 (0 K) 에서는, 전자가 안정적이므로 모든 전자가 Valence Band 에 모여있다. 온도가 상승하면 E k - - - - - : Electron : Hole -

4. Yonsei Univ. High-Speed Information Transmission Lab. Lect. 3-4-(4) Optical Amplifier 2003. 5. 19 (Mon.) Free space wavelength coverage by different LED materials from the visible spectrum to the infrared including wavelengths used in optical communications. Hatched region and dashed lines are indirect Eg materials. Conduction Band 와 Valence Band 의 peak 위치가 틀려서, pumping 을 해도 빛이 나오지 않는 다. 이러한 상태를 Indirect Bandgap 이라 하고 대표적으로 실리콘을 들 수 있다. E k 결국, 빛을 발생시키려면, Direct Bandgap 이어야 한다.

5. Yonsei Univ. High-Speed Information Transmission Lab. Lect. 3-4-(5) Optical Amplifier 2003. 5. 19 (Mon.)

6. Yonsei Univ. High-Speed Information Transmission Lab. Lect. 3-4-(6) Optical Amplifier 2003. 5. 19 (Mon.) ● SOA (Semiconductor Optical Amplifier) Electrical pumping by PN junction → Forward bias → Population Inversion → 빛 방출 → LED (Light Emitting Diode) → SOA Recall) Population Inversion 조건 At Semiconductor,