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Advances in optical and photonic devices Part 2

Tham khảo tài liệu 'advances in optical and photonic devices part 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Broadband Emission in Quantum-Dash Semiconductor Laser 11 dash variation from different dash stacks. The light-current L-I curve of the short cavity Qdash laser L 300pm yields a Jth and slope efficiency of 2.3 kA cm2 and 0.46 W A respectively as depicted in Fig. 7 a . Measuring the temperature dependent Jth over a range of 10-50 C reveals the temperature characteristic To of 41.3 K. On the other hand the long cavity Qdash laser L 1000pm yields Jth 1.18 kA cm2 slope efficiency of 0.215 W A and To of 46.7 K over the same temperature range as shown in Fig. 8 a . Fig. 6. The lasing spectra show the changes of multi-state emission from ground state GS first excited state ES 1 and second excited state ES 2 of the 50 x 500 pm2 broad area Qdash intermixed laser under different current injection of 1.1 x Ith 1.5 x Ith and 2.25 x Ith. Fig. 7. a L-I characteristics of the 50 x 300 pm2 broad area intermixed Qdash laser at different temperatures. Up to 450 mW total output power from both facets has been measured at J 4.0 x Jth at 20 C. b The progressive change of lasing spectra above threshold condition. Compared to the laser with long cavity the shorter cavity laser exhibits the progressive appearance of short wavelength emission line with an increase in injection level. The L-I curve of the short cavity laser shows kinks as compared to the long cavity laser. The jagged L-I curve below 3 x Jth implies that the lasing actions from different confined energy levels are not stable due to the occurrence of energy exchange between short and long wavelength 12 Advances in Optical and Photonic Devices Fig. 8. a L-I characteristics of the 50 x 1000 m2 broad area intermixed Qdash laser at different temperatures. Up to 340 mW total output power from both facets has been measured at J 4.0 x Jth at 20 C. b The progressive change of lasing spectra above threshold condition. lasing modes Hadass et al. 2004 as can be seen in the lasing spectra of Fig. 7 b . In addition the observation of kink