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Optical Properties of Quantum Nanostructures
Published in Jyoti Prasad Banerjee, Suranjana Banerjee, Physics of Semiconductors and Nanostructures, 2019
Jyoti Prasad Banerjee, Suranjana Banerjee
This chapter deals with studies on optical properties of low-dimensional semiconductor structures such as quantum well, wire, and dots. These studies provide the necessary tools for experimental verification of Density of States (DOS) function and the existence of excitons in low-dimensional systems. The basic principle of new generation of optoelectronic and photonic devices based on quantum nanostructures such as Quantum Well Laser (QWL), Quantum Dot Laser (QDL), Infrared Photodetector, and electro-optic modulators will be introduced here. The principle of operation of these devices can be understood from the fundamental optoelectronic properties of low-dimensional semiconductors. With the advent of modern epitaxial growth techniques and fine line lithography (FLL), the practical realization of the aforementioned nano-photonic devices has become a reality. Many of these devices are routinely fabricated, showing improved performance.
Modulation for Short-Reach Access Optical Transmission
Published in Le Nguyen Binh, Optical Modulation, 2017
In access networks, the 1300 nm can be employed to avoid the dispersion effects of the SSMF. One such comb laser in the 1310 nm is shown in Figure 9.60a. The cob laser is fabricated using quantum dot structures in InGaAs with flat broadband mirror at the two end of the laser cavity [39]. A comb line can be filtered as shown in Figure 9.60b. Such a comb laser in the 550 nm region can be generated by an embedded modulator in a quantum dot laser cavity as reported in References 40 and 41. These comb lasers would offer the generation of modulated channels reaching a total capacity of 9.4 Tbps over the entire C-band with 100 Gbps per channel and 94 sub-carriers of 50 GHz spacing. This band has now been extended to 94 wavelength carriers as optical amplifiers have been available and optimized over the C-band.
Lasers and Their Emission Characteristics
Published in F.J. Duarte, Tunable Laser Optics, 2017
Quantum dot lasers engineered with external cavities have demonstrated tuning ranges within the 1000 ≤ λ ≤ 1300 nm region as indicated in Table 9.26. A tunable quantum dot laser, using InAs as gain medium and employing a diffraction grating deployed in Littrow configuration, is reported to yield a laser linewidth of Δν ≈ 200 kHz and a tuning range of 1125 ≤ λ ≤ 1288 nm. Frequency stabilization reduced the linewidth to Δν ≈ 30 kHz (Nevsky et al. 2008).
Fuzzy logic based feedback control system for the frequency stabilization of external-cavity semiconductor lasers
Published in International Journal of Optomechatronics, 2020
Yang Wang, Xiaoyan Wu, Yuhang Wang, Xiaoping Zhou
According to the principle of the feedback control loop,[17] the schematic diagram of the ECL frequency stabilization system is shown in Figure 1. The laser diode was mounted on a Peltier cooler at a temperature of 20 °C[18] and was constructed in a Littrow external-cavity configuration. Here we choose the Littrow configuration to build the ECL model, which is simpler and more convenient than the Littman configuration. The laser diode was a home-made InAs/InP quantum dot laser, with the center wavelength at around 1.55 μm. In Figure 1, the light emitted from the front facet of the laser diode were collimated by a lens and the first-order diffracted light were reflected back by grating and fed into the laser diode again. The light emitted from the back facet of the laser diode were collimated as well for optical frequency measurement. The optical frequency measurement is an optical wavelength meter, which responses to the ECL output frequency fastly and accurately. The optical output frequency of the ECL is determined by the first-order diffracted light, which is controlled by the rotation angle of the grating.[19]