Mode characteristics for 1.55 μm square microcavity laser monolithically integrated on GaAs substrates

We report a 1.55μm square microcavity laser monolithically integrated on GaAs substrates. The mode characteristics of the microcavity laser are numerically investigated by three-dimensional finite difference time domain method. The dependences of the whispering-gallery modes on the width of the output waveguide and the etching depth are discussed. For the cavity with the side length of 12μm and the output waveguide of 1μm, it is easy to excite whispering-gallery modes around 1.55μm. The mode wavelength is 1542.88nm and the mode Q factor is 2389.23. The Q factor degrades rapidly with the waveguide width increasing and increases with the increasing of the etching depth.