In addition to well-known effects, such as Stimulated Raman/Brillouin Scattering (SRS/SBS), Prof. Zervas will focus on thermally-driven nonlinear effects, such as thermal lensing (TL) and transverse modal instability (TMI). In addition, Prof. Zervas will consider the limitations introduced by the pump brightness and the mechanical reliability of packaged bent fibers. This results in the introduction of a critical pump brightness, i.e. the required minimum pump brightness at which the maximum signal power is achieved. The maximum achievable power is shown to depend primarily on the choice of fiber design, pumping wavelength, amplifier gain and heat coefficient.

In the case of SRS/TMI limited operation, maximum signal powers of ~28kW to ~38kW, for diode pumping (λp=976nm), and ~35kW to ~52kW, for tandem pumping (λp=1018nm), are predicted for single-mode fiber amplifiers operating at signal wavelength λs=1070nm, when the amplifier gain is increased from 10dB to 20dB. For an amplifier gain of 10dB, the maximum achievable signal power varies from 85kW to 25kW for tandem pumping, and 35kW to 20kW for diode pumping, when the heat coefficient varies from 1% to 15% and 5.5% to 20%, respectively. In the case of SBS/TMI limited operation, maximum signal powers of ~7-16kW are predicted, depending on the pump brightness and fiber design.

What You Will Learn:
• Thermally-driven limiting effects in fiber amplifiers, such as thermal lensing and transverse modal instability
• Impact of pump brightness and bend-induced mechanical reliability of fibers
• Interplay with well-known fiber nonlinearities, such as SRS and SBS

Who Should Attend:
• Graduate students
• Laser technology researchers
• Laser research and development engineers

About the Presenter: Michalis N. Zervas from Optoelectronics Research Centre, University of Southampton

Michalis graduated from the Electrical Engineering Department, University of Thessaloniki, Greece and received his PhD degree in Fibre Optics from University College London.  He joined the Optoelectronics Research Centre, University of Southampton in 1991 as a Research Fellow, promoted to Research Lecturer in 1995 and Professor in Optical Communications in 1999.  In 2016 he was awarded the prestigious Royal Academy of Engineering Chair in Advanced Fibre Laser Technologies for Future Manufacturing.  His research activities include  advanced optical fibre amplifier configurations, high power fibre lasers, fibre DFB lasers, Bragg grating theory and devices, surface-plasmon effects and devices, optical microresonators, and non-linear fibre optics.  He is a co-founder of Southampton Photonics Inc., a University of Southampton spin-off, now SPI Lasers Ltd, manufacturing high power fibre lasers, where he served as Chief Scientist from 2003 to 2016. He has authored/coauthored over 340 technical publications, about 40 patents/patent applications (of which 20 are granted) and has served on various conference program committees. He was the General Program Chair of the 1999 Optical Amplifiers Meeting (OSA) in Japan and General Chair of Specialty Optical Fibers (SOF) – OSA Advanced Photonics Congress in 2018. He has given a number of invited talks, tutorials and short courses in fiber amplifiers, fibre lasers and fiber Bragg gratings at major international conferences. He was a guest editor of the journal "Journal of Selected Topics in Quantum Electronics", special issue on Advanced Fibres and Waveguides. In 1996 he shared the prestigious Metrology award from the Confederation of British Industry for his work on grating measuring systems for characterizing reflection and dispersion performance of fiber Bragg gratings.   In 2006 he was finalist for the Royal Society of Engineering McRobert Award for the development of high power industrial fibre lasers.  He is Associate Editor of Optics Express and an Optical Society of America Fellow since 2015.