TAILIEUCHUNG - Optoelectronics Devices and Applications Part 7

Tham khảo tài liệu 'optoelectronics devices and applications part 7', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | The Vertical-Cavity Surface Emitting Laser VCSEL and Electrical Access Contribution 229 Fig. 3. Vertical-Cavity Surface-Emitting Laser Vertical-Cavity Surface-Emitting Laser with GaInAsP InP and AlGaAs GaAs active region for optical fiber communications for the optical disks optical sensing and optical processing. The first goal of Prof. Iga was to grow a monolithic structure in a wafer and test the component before separation. In 1979 the first lasing surface emitting laser SEL was obtained with a GaInAsP InP structure at 77K under pulsed regime. The threshold current was about 900mA within or wavelength. In 1983 the first lasing at room temperature RT under pulsed operation with a GaAs active region was achieved but the threshold current remained higher than the Edge Emitting Laser EEL . In spite of the poor VCSEL performance in those days the progress of the microelectronic technology gave the opportunity to the researcher to improve the VCSEL structure in view of threshold reduction at RT. After a decade of improvement attempts the first continuous wave CW operation at RT was obtained by Iga with a GaAs structure. At the same time Ibariki Ibaraki et al. 1989 introduced into the VCSEL structure doped Distributed Bragg Reflector DBR as mirrors as well for the current injection. Jewell Jewell et al. 1989 presented the first characterisation of Quantum Wells QW GaAs Based Vertical-Cavity Surface Emitting Laser where the DBR and QW introduction is an important breakthrough for the VCSEL technology advance DBR involves the increase of the reflection coefficient and the QW strongly reduces the threshold current up to few milliamps. Furthermore the growth of the VCSEL structure by Molecular Beam Epitaxy MBE was a crucial advance toward its performance enhancement. MBE led to a broad-based production mainly for the AlGaAs GaAs structure involving cost effectiveness. Thus at the beginning of the 90 s we could find the 850nm VCSEL structure presented on Fig. 3

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