Highly Efficient Second-Harmonic Generation in Monolithic Matching Layer Enhanced Al$_x$ Ga$_{1-x}$ As Bragg Reflection Waveguides

In this letter, we demonstrate significant improvement in second-harmonic (SH) generation using matching layer enhanced Al
_x
Ga
_1-x
As Bragg reflection waveguide in type-I and type-II phase-matching schemes. For a 1.8-ps pulsed pump around 1550 nm with an average power of 3.3 mW, peak SH powers of 28 and 60 muW were measured in type-I and type-II interactions, respectively. The associated normalized conversion efficiencies were estimated to be 5.30 times 10
³
% and 1.14 times 10
⁴
% W
^-1
middot cm
^-2
with SH process bandwidths of 1.7- and 1.8-nm full-width at half-maximum. Waveguides with various ridge widths ranging between 2.8 and 4.8 mum with 2.17-mm length were characterized.