WECSL

We have designed and demonstrated a new waveguide external-cavity semiconductor laser (WECSL Ô ) using grating feedback in Littrow configuration in a planar optical-waveguide form factor. A novel liquid crystal waveguide geometry provides a giant electro-optic effect capable of changing the effective index by D neff = 0.02. This forms the basis for extended synchronous tuning of both the optical path delay (OPD) and lasing wavelength. The waveguide is coupled to commercially available laser diodes with either microlenses or direct butt coupling. The light from the laser then passes through an OPD tuning element and a beamsteering element before encountering a blazed reflection grating bonded to the end facet of the waveguide resulting in an entirely electro optic and monolithic device. The unused facet from the laser diode provides a non-steering output and another steering output can be taken from the grating.

The WECSL can be designed to tune over 100 nm ranges for applications such as distributed fiber sensing or detection of multiple trace-gas species. Alternatively, for sensing of a single trace-gas specie, the center frequency of the WECSL can be adjusted during manufacturing to tune over a smaller range anywhere inside the gain profile of the laser diode. In addition to providing electronic tuning in a environmentally robust package, the WECSL design reduces manufacturing costs of external-cavity tunable diode lasers while maintaining their primary benefits such as spectral linewidth, side-band suppression ratio, and continuous mode-hop-free tuning range. Recent results will be presented.

To download a poster on this technology from the 2006 International Liquid Crystal Conference click here.