Title :
On the spectral properties of widely tunable lasers using grating-assisted codirectional coupling
Author :
Chuang, Z.M. ; Coldren, L.A.
Author_Institution :
Dept. of Electr. & Comput. Eng., California Univ., Santa Barbara, CA, USA
Abstract :
The analysis of mode-suppression-ratio (MSR) and wavelength tunability of widely tunable semiconductor lasers using grating-assisted codirectional-coupler (GACC) filters is considered. A tradeoff is found between tuning range and spectral purity when using this type of filter as an intracavity mode selector. It is shown that in order to improve the tuning range by a factor of 10 compared to a conventional tunable laser using distributed feedback reflectors (DBRs), one has to tolerate a MSR around 23 dB at 1 mW output optical power/facet for an ideal cavity design. Limitations imposed by the materials are illustrated with design curves based on a vertical-twin-guide structure in both GaAs and InP systems for lasing wavelengths at 0.98 and 1.55 mu m, respectively.<>
Keywords :
diffraction gratings; directional couplers; integrated optics; laser cavity resonators; laser modes; laser tuning; optical couplers; optical filters; semiconductor lasers; 0.98 micron; 1 mW; 1.55 micron; GaAs; GaAs-AlGaAs; InP; InP-InGaAsP; design curves; filters; grating-assisted codirectional coupling; ideal cavity design; intracavity mode selector; mode-suppression-ratio; output optical power; semiconductor lasers; spectral properties; spectral purity; tuning range; vertical-twin-guide structure; wavelength tunability; widely tunable lasers; Distributed feedback devices; Gratings; Laser feedback; Laser modes; Laser tuning; Optical filters; Optical tuning; Power lasers; Semiconductor lasers; Tunable circuits and devices;
Journal_Title :
Photonics Technology Letters, IEEE
