Title :
Long-wavelength InGaAsP/InP distributed feedback lasers incorporating gain-coupled mechanism
Author :
Tsang, W.T. ; Choa, F.S. ; Wu, M.C. ; Chen, Y.K. ; Logan, R.A. ; Sergent, A.M. ; Burrus, C.A.
Author_Institution :
AT&T Bell Labs., Murray Hill, NJ, USA
fDate :
3/1/1992 12:00:00 AM
Abstract :
Successful operation of long-wavelength InGaAsP low-threshold-current gain-coupled DFB lasers was demonstrated by using an InGaAsP quaternary grating that absorbs the DFB (distributed feedback) emission. The amount of gain (loss)-coupling is controlled by the composition (bandgap) and thickness of the grating quaternary and the InP-spacer layer between the grating and the active layer. With optimally designed lasers, CW (continuous-wave) threshold currents were 10-15 mA (250- mu m cavity, as-cleaved), slope efficiency was approximately 0.4 mW/mA (both facets) and SMSR (side-mode suppression ratio) was as high as 52 dB. The laser operated in the same DFB mode with SMSR staying approximately 50 dB throughout the entire current range. At 100 degrees C, the CW threshold current stayed low, approximately 50 mA, and SMSR was approximately 40 dB. Results also indicate that the presence of gain-coupling removes the degeneracy in lasing wavelength.<>
Keywords :
III-V semiconductors; diffraction gratings; distributed feedback lasers; gallium arsenide; gallium compounds; indium compounds; laser modes; semiconductor junction lasers; 10 to 15 mA; 100 degC; 50 mA; CW lasing; CW threshold current; DFB lasers; DFB mode; InGaAsP-InP; InP-spacer layer; active layer; as-cleaved; distributed feedback lasers; gain-coupled; gain-coupled mechanism; grating quaternary layer thickness; long-wavelength; low-threshold-current; quaternary grating; semiconductors; side-mode suppression ratio; slope efficiency; Distributed feedback devices; Gratings; Indium phosphide; Laser feedback; Laser modes; Laser theory; Performance gain; Phase modulation; Semiconductor lasers; Threshold current;
Journal_Title :
Photonics Technology Letters, IEEE
