Two-dimensional simulation of high-order laterally-coupled GaAs-AlGaAs DFB laser diodes

Abstract

Laterally-coupled distributed feedback (LC-DFB) laser diodes made without an epitaxial re-growth process have the advantage of a simple fabrication process. In this paper, two-dimensional optical field distribution of the fundamental quasi TE (transverse electric) mode is calculated by means of a semivectorial finite-difference method (SV-FDM). The dependence of the effective coupling coefficient (κ eff ) on the dutycycle of first-, second-and third-order LC-DFB LDs is investigated using modified coupled wave equations.

Dynamic analysis of high-order quantum dot based laterally-coupled distributed feedback lasers

“…This light is responsible for a complex effective coupling coefficient which, for higher-order gratings, can be significantly different than the first-order approximation 19 . As a result, the coupling coefficient evaluation in this paper has been extended to include Streifer et al's modified coupledmode analysis 6 .…”

GaN-based distributed feedback laser diodes for optical communications

“…To maximise the coupling coefficient, as 3 rd order gratings exhibit weaker coupling coefficients compared to their 1 st -order counterparts, an 80% duty cycle was implemented for the application of a third order grating [11]. In this work, however, devices based on 39 th order notched gratings were used [12], which provide somewhat easier etching methods compared to a previously discussed 3 rd -order grating device [7] [10]. The main advantage of the higher-order grating geometry is the potential for a much narrower linewidth.…”

Y-branch coupled DFB-lasers based on high-order Bragg gratings for wavelength stabilization

“…Because the grating section in DFB-lasers must be pumped electrically, the use of first-to third-order deeply etched gratings is hard to realize. DFB-lasers made without grating overgrowth are, therefore, often based on side coupled gratings [9][10][11][12][13][14]. However, side coupled gratings have two disadvantages.…”

“…First, the overlap between the fundamental mode and the grating is low [15], which can result in undesirable higher order mode lasing. Second, the duty cycle of the gratings is very sensitive to the waveguide width [14,15].…”