Improvement of amplified spontaneous emission performance of conjugated polymer waveguides with a low loss cladding

Abstract

We report the improvement of the amplified spontaneous emission (ASE) performance in the optically pumped symmetric thin film waveguide glass/indium-tin oxide (ITO)/SiO2/poly[2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylenevinylene]/SiO2/Al or Ag by optimizing the thickness of SiO2 and replacing the Al electrode with Ag, where SiO2 acted as a spacer layer to prevent the ASE at 620 nm from being destructed. The results show that the SiO2/Ag cladding reduced the ASE threshold to 4 μJ/pulse compared with the SiO2/Al cladding, owing to the higher work function and reflection rate as well as lower absorption loss of the Ag electrode. No photoluminescence at 580 nm being observed makes it possible for an electric field to only modulate the ASE at 620 nm in the device with the SiO2/Ag cladding. The electric-field quenching of the ASE has been observed, which increases with the electric field. The field dependence of ASE can be attributed to field-induced dissociation of photogenerated excitons in the polymer waveguides.

Significant Lowering Optical Loss of Electrodes via using Conjugated Polyelectrolytes Interlayer for Organic Laser in Electrically Driven Device Configuration

“…The refractive index (n) at wavelength of 450 nm is 1.76 for PFO, 1.46 for quartz, 1.53 for glass and 1.9 for ITO. The relatively high index of ITO lead to high optical leakage loss between PFO and ITO interface, i.e., bad optical confinement 2 13 14 , therefore, high ASE threshold. On the other hand, the extremely rough surface of ITO causes strong scattering loss 18 21 .…”

“…This problem has to be addressed in device configuration. Although thermally evaporated or sputtered SiO 2 layers with about 100 nm thickness have been introduced between electrode and gain media to reduce the losses associated with the electrode contact 13 14 15 , SiO 2 could also block electrons and holes injecting from electrode into the active layer due to its insulation character. As a result, the device with SiO 2 as interlayer is hardly to reach the high current density required by laser action.…”

Conjugated polymer-based broadband terahertz wave modulator

“…However, the processing of small organic molecules for device fabrication is more complex (and expensive) than the processing of conjugated polymers. Conjugated polymers have attracted considerable interest for applications in the fields of light-emitting diodes, flat panel displays, and solar cells, because they are compatible with inorganic semiconductors, have high photoluminescence quantum efficiencies, and are inexpensive to fabricate [12][13][14][15][16][17]. Additionally, most conjugated polymers are transparent in the THz range, and they have not yet been used in THz modulators and switches.…”

“…The generated THz pulses had a normal angle of incidence to the polymer/inorganic hybrid structures, while the external CW semiconductor laser beam had an oblique angle of incidence. The external CW laser beam has a wavelength of 450 nm, which is strongly absorbed by silicon, although it locates in the absorption band of MEH-PPV [15,16,18]. The transmitted THz waveform was detected using a ZnTe crystal, with an electro-optic sampling technique [19].…”

Enhancement of optical gain and amplified spontaneous emission due to waveguide geometry in the conjugated polymer poly[2-methoxy-5-(2′-ethylhexyloxy)-p-phenylene vinylene]

“…Note that while ASE threshold reductions have recently been demonstrated using glass/indium-tin oxide (ITO)/SiO 2 /MEH-PPV/SiO 2 /Ag SWG structures, the performance enhancements were achieved based on optimization of the SiO 2 spacer layer thickness; however, there was no analysis provided regarding the influence of WG symmetry and mode confinement on threshold and gain. 24 MEH-PPV was purchased from Sigma-Aldrich and used as received. Asymmetric WGs of Si(100)/SiO 2 /MEH-PPV/ air were fabricated by spin coating films of MEH-PPV from 1.0% w/v chlorobenzene solution onto Si(100) substrates with a 1-lm-thick layer of thermally grown oxide.…”