Comparative Study of Passive Modelocking Configurations in Semiconductor Lasers

Camacho Paez, Fernando (1997) Comparative Study of Passive Modelocking Configurations in Semiconductor Lasers. PhD thesis, University of Glasgow.

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Abstract

This thesis is concerned with the investigation of different configurations of semiconductor lasers to generate short optical pulses through passive modelocking, and the analysis of the possible uses for these optical pulse generators. Three different modelocking configurations have been studied to generate optical pulses at frequencies between 1 and 15 GHz; two of them monolithic configurations, namely all active cavity mode-locked lasers and extended cavity mode-locked lasers and the third one being an external cavity configuration. The all active cavity mode-locked lasers have the advantage of having the easiest and most reliable fabrication process, but exhibited high threshold, around 100 mA for 5 mm long laser, broad pulses, around 10 ps, and high timing jitter levels, up to 22 ps (1 kHz-l0MHz). The extended cavity mode-locked lasers, which incorporate active and passive sections, are also easy to fabricate, but the reliability of the fabrication process depends on the reliability of the technique to fabricate the passive section of the device. They are excellent short pulse generators with very low threshold current, around 25 mA for a 5 mm long laser, pulses as narrow as 3.5 ps and jitter levels as low as 9 ps (1 kHz- 10MHz), which indicates a high stability in the pulse generation. With the external cavity configuration the pulse generation frequency can be reduced to values as low as hundreds of MHz. The drawback with this type of laser is their mechanical instability, which makes them a difficult device to work with. An important application for these optical pulse generators is that of all-optical clock recovery. The locking range of the monolithic configurations, under external periodic excitation, was studied. The all active cavity lasers showed a locking range wider than 0.15% of the free running modelocking frequency, whilst the extended cavity lasers locking range was around 0.03% of the free running modelocking frequency.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: John Marsh
Keywords: Electrical engineering
Date of Award: 1997
Depositing User: Enlighten Team
Unique ID: glathesis:1997-75184
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 19 Nov 2019 21:51
Last Modified: 19 Nov 2019 21:51
URI: http://theses.gla.ac.uk/id/eprint/75184

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