Low-loss, single-mode GaAs/AlGaAs waveguides with large core thickness

Low-loss, single-mode waveguides with a large core thickness have been designed and fabricated in gallium arsenide/aluminium gallium arsenide waveguides. Detailed beam propagation method simulations were carried out to investigate the modal properties of the waveguides and were compared with measured results. For lengths of 2 cm, insertion losses of ≤3.5 dB were achieved when coupled to conical lensed fibre. This demonstrates a simple method of achieving minimal coupling losses without the need for complex structures such as waveguide tapers. In addition, the propagation loss was measured to have a low value of 0.2±0.09 dB/cm.