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Title: Self-pulsing 1050 nm quantum dot edge emitting laser diodes for optical coherence tomography
Author: Liu, Haoling
ISNI:       0000 0004 2750 812X
Awarding Body: Cardiff University
Current Institution: Cardiff University
Date of Award: 2010
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Self pulsed quantum dot lasers are proposed as a means to generate broadband emission in the 1050 nm region for optical coherence tomography applications. Existing quantum dot materials which are not intentionally designed for broad band emission are examined. Devices for self pulsation are configured with sr. it contacts. When operated without a saturable absorber the laser emits a number of discrete narrow (1 nm) modes, which merge to form a broad continuous lasing spectrum (10 nm) on application of the saturable absorber. Under a continuous drive current, a single mode ridge waveguide laser was operated at 15 C such that a spectral width of 10 nm at FWHM centred at 10'SO nm with an average output power of 7.5 mW was achieved. The measured gain/loss spectra have been used in a rate equation modal to explain the spectral broadening that has been obtained and to show that the broadened spectra are consistent with the modulated carrier density expected under Q-switched ope i- tion. The mechanism and the operational principle of self pulsation quantum dot lasers have been studied. A comparison with a quantum well material shows that the realisation of self pulsation and the spectrum broadening induced by the self pulsation are closely related to the specific gain spectra of the quantum dot ma e- rials. A self pulsed quantum well laser only emits light with a bandwidth of 2 5 nm. Experimental result and simulation show that a bandwidth of 30 nm may be obtained from the existing quantum dot material. If self pulsation can be per formed using an intentionally designed quantum dot material for broadband emission, even broader bandwidth may be obtained. This provides a simple technique for generation of fast broadband laser emission not only for OCT but also for other applications.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available