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Distributed Feedback Lasers Based on Green Fluorescent Protein and Conformal High Refractive Index Oxide Layers
Author(s) -
Karl Markus,
Meek Andrew,
Murawski Caroline,
Tropf Laura,
Keum Changmin,
Schubert Marcel,
Samuel Ifor D. W.,
Turnbull Graham A.,
Gather Malte C.
Publication year - 2020
Publication title -
laser and photonics reviews
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.778
H-Index - 116
eISSN - 1863-8899
pISSN - 1863-8880
DOI - 10.1002/lpor.202000101
Subject(s) - materials science , laser , lasing threshold , net gain , refractive index , optoelectronics , optics , resonator , waveguide , high refractive index polymer , wavelength , cmos , amplifier , physics
Fluorescent proteins have emerged as an attractive gain material for lasers, especially for devices requiring biocompatibility. However, due to their optical properties, integration with distributed feedback (DFB) resonators is not readily achievable. Here, a DFB laser with enhanced green fluorescent protein (eGFP) as the gain material is demonstrated by incorporating a thin (65 nm), high refractive index ( n = 2.12) ZrO 2 interlayer as waveguide core. Deposition of ZrO 2 via atomic layer deposition yields a smooth and conformal film as required to minimize optical losses. Lasing emission is obtained from 2D second‐order DFB eGFP lasers at pump power densities above 56.6 kW cm –2 and a wavelength tuning range of Δ λ = 51.7 nm is demonstrated. Furthermore, it is shown that in contrast to conventional organic DFB lasers, both transverse electric (TE) and transverse magnetic (TM) modes are accessible. The effective refractive index of these modes can be predicted accurately through optical modelling. Using far‐field imaging, the laser beam profile is studied and TE and TM modes are distinguished.