Thesis

Organic lasers and nanostructred organic films for hybrid integration

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Awarding institution
  • University of Strathclyde
Date of award
  • 2012
Thesis identifier
  • T13331
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Abstract
  • Light emitting polymers (LEPs) are a promising category of organic materials for photonic applications owing to their potential for simple fabrication and availability of materials emitting across the whole visible spectrum. LEPs are already exploited commercially in the case organic light emitting diodes and their interesting properties for colour conversion and as laser gain material are under investigation. To keep the LEPs' benefit of simple and low-cost fabrication, integration onto inorganic semiconductor devices such as in particular gallium nitride light emitting diodes (LEDs) is an important research topic. In this thesis, developments towards integration of organic devices onto micro-pixellated ip-chip LEDs are presented. This particular format may be beneficial for applications such as displays, various sensing schemes and data transmission owing to spatio-temporal control, high modulation bandwidths and potential for simple integration with complementary metal oxide semiconductor electronics. The properties of LEP films as optical gain medium were assessed on smooth and corrugated substrates. In the former case, random laser action (RL) was observed which is attributed to the high optical gain delivered by these materials. Arguments are presented suggesting that RL may be very common in high gain media. In the latter case, mechanically flexible distributed feedback lasers were fabricated in a very simple way and their properties including operational lifetime were characterised. Nano-patterned LEP films for colour conversion of LED light exhibited strong modification of the LEP emission due to the photonic crystal (PhC) effect of the periodic pattern. PhCs allow tailoring of the emission properties by appropriate design of the nano-pattern and they can be created relatively easy in organic films. Furthermore, the modulation bandwidth of an organic PhC film excited by micro-LEDs was measured to be 168 MHz and was mainly limited by the inorganic LED. This underpins the potential of LEPs for communications applications. The suitability of micro-LEDs in flip-chip format as pump source for organic semiconductor lasers was investigated. For this purpose, stripe-shaped arrays of micro-LEDs were developed that were employed for the demonstration of the first micro-LED pumped polymer laser.
Resource Type
DOI
Date Created
  • 2012
Former identifier
  • 967009

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