A simple perturbative analysis for fast design of an electrically pumped micro-disk laser

Abstract

A perturbative analysis is proposed to estimate optical losses for electrically pumped micro-disk lasers. The optical field interaction with the electrical contacts and the optimization of their implementation is investigated. Our model shows a good agreement with 3D Finite Difference Time Domain (FDTD) computation and can be used for designing contacts for thin micro-disks, with a considerably reduced calculation time. We also demonstrate that losses induced by the contacts can be exploited to select the optical mode of a micro-laser.

Nanophotonic Devices for Optical Interconnect

“…By careful design of the metal top contact and the position of the gain layer the modes (0, m, 0) will have a considerable lower intrinsic loss rate τ −1 0 , compared to the higher order modes with nonzero l and n numbers and will have a much lower threshold gain [31]. However, there is no clear mechanism to select the azimuthal mode number m. For microdisks with radius larger than 2 µm, the FSR will typically be smaller than the gain bandwidth and lasing in multiple orders may occur.…”

“…The laser mode is evanescently coupled to this waveguide. Careful alignment of the disk with respect to the waveguide is important to achieve a good coupling efficiency (see [31] for details on the disk-waveguide coupling design). Electrical injection is possible via a top metal contact in the cm −3 ) InP contact layer.…”

Improvement of threshold and mode selectivity of a microdisk laser by engineering its coupling to an external passive cavity

“…The very thin high index layer (called "slab"), leads to low Q factors compared to the intrinsic ones [7]. It can be demonstrated that a 100 nm thick slab leads to quality factors limited to a few tens of thousands for 2.5 μm radius micro-disks, around λ =1.55 μm, and, if a top contact is overpassing this weakly confined slab waveguide, global losses can be increased due to absorption in the top contact [8]. Moreover, the undesired coupling between the Si waveguide and the slab must be avoided.…”

“…This model provides a very accurate value of the resonant wavelengths and 3D field compared to 3D FDTD [8] when given the geometry of the disk, optical indexes and the 3 mode orders (l, m, n) : radial, azimuthal, and vertical order. We define the Free Spectral Range for Transverse Electrical (TE) modes (F SR T E ), as the frequency difference between modes T E(l, m+1, n) and T E(l, m, n).…”

CMOS CW tunable III–V microdisk LASERs for optical interconnects in integrated circuits

“…Fabrication and microdisks design, including their contacts position and coupling to Si waveguides, are detailed in [5], [6]. A 3D drawing of such a LASER is shown in fig.…”