CUED Publications database

169 GHz repetition rate passively harmonically mode-locked VECSEL emitting 265 fs pulses

Quarterman, AH and Wilcox, KG and Perevedentsev, A and Apostolopoulos, V and Mihoubi, Z and Chung, AL and Beere, HE and Farrer, I and Ritchie, DA and Tropper, AC (2011) 169 GHz repetition rate passively harmonically mode-locked VECSEL emitting 265 fs pulses. Proceedings of SPIE - The International Society for Optical Engineering, 7919. ISSN 0277-786X (Unpublished)

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High repetition rate passively mode-locked sources are of significant interest due to their potential for applications including optical clocking, optical sampling, communications and others. Due to their short excited state lifetimes mode-locked VECSELs are ideally suited to high repetition rate operation, however fundamentally mode-locked quantum well-based VECSELs have not achieved repetition rates above 10 GHz due to the limitations placed on the cavity geometry by the requirement that the saturable absorber saturates more quickly than the gain. This issue has been overcome by the use of quantum dot-based saturable absorbers with lower saturation fluences leading to repetition rates up to 50 GHz, but sub-picosecond pulses have not been achieved at these repetition rates. We present a passively harmonically mode-locked VECSEL emitting pulses of 265 fs duration at a repetition rate of 169 GHz with an output power of 20 mW. The laser is based around an antiresonant 6 quantum well gain sample and is mode-locked using a semiconductor saturable absorber mirror. Harmonic modelocking is achieved by using an intracavity sapphire etalon. The sapphire then acts as a coupled cavity, setting the repetition rate of the laser while still allowing a tight focus on the saturable absorber. RF spectra of the laser output show no peaks at harmonics of the fundamental repetition rate up to 26 GHz, indicating stable harmonic modelocking. Autocorrelations reveal groups of pulses circulating in the cavity as a result of an increased tendency towards Q-switched modelocking due to the low pulse energies.

Item Type: Article
Divisions: Div B > Photonics
Depositing User: Cron Job
Date Deposited: 17 Jul 2017 19:17
Last Modified: 25 May 2018 20:26