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Port Glasgow, United Kingdom

Nshii C.C.,University of Glasgow | Ironside C.N.,University of Glasgow | Sorel M.,University of Glasgow | Slight T.J.,University of Glasgow | And 4 more authors.
Applied Physics Letters | Year: 2010

We report on the design, fabrication, and characterization of a unidirectional quantum cascade ring laser operating at a wavelength of around 3.4 μm at 200 K. A unidirectional operation is achieved by incorporating an "S-shaped" crossover waveguide in a manner that it couples light from the counterclockwise direction to the preferred clockwise direction. The ring laser unidirectionality is confirmed by measuring the counterpropagating wave suppression ratio (CWSR) as a function of injection current. At 1.5 times the threshold current, the CWSR is 9 that is 90% of the light is emitted in the favored (clockwise) direction. © 2010 American Institute of Physics.

Dhirhe D.,University of Glasgow | Slight T.J.,CST Global Ltd | Holmes B.M.,University of Glasgow | Ironside C.N.,University of Glasgow
Optics Express | Year: 2013

We discuss the design, modelling, fabrication and characterisation of an integrated tuneable birefringent waveguide for quantum cascade lasers. We have fabricated quantum cascade lasers operating at wavelengths around 4450 nm that include polarisation mode converters and a differential phase shift section. We employed below laser threshold electroluminescence to investigate the single pass operation of the integrated device. We use a theory based on the electro-optic properties of birefringence in quantum cascade laser waveguides combined with a Jones matrix based description to gain an understanding of the electroluminescence results. With the quantum cascade lasers operating above threshold we demonstrated polarisation control of the output. © 2013 Optical Society of America.

Dhirhe D.,University of Glasgow | Slight T.J.,CST Global Ltd | Nshii C.C.,University of Strathclyde | Ironside C.N.,University of Glasgow
Semiconductor Science and Technology | Year: 2012

The design, fabrication and characterization of a monolithic double-ring quantum- cascade laser (DRQCL) are described. At a wavelength of 4.6m, we demonstrate tunable, single-mode operation of a DRQCL and use it as a source for spectroscopy of CO gas. © 2012 IOP Publishing Ltd.

Dhirhe D.,University of Glasgow | Slight T.J.,CST Global Ltd | Holmes B.M.,University of Glasgow | Hutchings D.C.,University of Glasgow | Ironside C.N.,University of Glasgow
Optics InfoBase Conference Papers | Year: 2012

By integrating a polarization mode converter we have obtained significant amounts of Transverse Electrical light from a quantum cascade laser. First results indicate up to around 18%TE light in an elliptically polarized output. © OSA 2012.

Hou L.,University of Glasgow | Tan M.,University of Glasgow | Haji M.,University of Glasgow | Eddie I.,CST Global Ltd | Marsh J.H.,University of Glasgow
IEEE Photonics Technology Letters | Year: 2013

We, for the first time, present electroabsorption modulator lasers based on side-wall gratings and the identical epitaxial layer scheme using very simple fabrication processes. The devices show stable single-mode operation with little mode-hopping and a side mode suppression ratio of more than 45 dB, which is maintained until the applied current exceeds 6 times that of the threshold value. The drive voltage required to obtain a 12-dB extinction ratio is-2V. The devices can be operated with a 3-dB bandwidth of 7 GHz allowing for error-free large signal modulation at 5 Gb/s with a dynamic extinction ratio of 11 dB. © 1989-2012 IEEE.

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