Inverse Design for Full Control of Spontaneous Emission Using Light Emitting Scattering Optical Elements

Full control of spontaneous emission is essential in various fields of optics. This work presents an inverse designed light-emitting scattering optical element that includes full control of spontaneously emitted photons (i.e., enhancement at a central frequency and suppression at neighboring frequencies) and directionality of the output beam. This is achieved by embedding a one-dimensional optical active element inside a cluster of square shaped gallium arsenide dielectric rods whose positions are optimized by a genetic algorithm. Large spontaneous emission enhancement of $>70$ is predicted at the transition wavelength if high-quality sources are employed. Moreover, neighboring wavelengths are simultaneously suppressed over 10 times. Finally, the radiated beam is highly collimated to only 6° and contains 30 times the energy emitted by the source placed in free space.

Figure 1

Schematic view of a light-emitting SOE. An active optical element (yellow rod) is incorporated into the central plate. The red beam illustrates the collimated emitted light. The white plane is an image projection of the emitted light in the far field.

Figure 2

Performance of the optimized LE-SOE device at the central wavelength of the emitting source. (a) Amplitude of the electric field showing the collimation of light emission in the far field. (b) The real part of the electric field in near field. The white squares represent the position of GaAs rods in the LE-SOE device. The unit length, $a$, in both figures represents the thickness of the plates proposed in the fabrication method.

Figure 3

Spontaneous emission modification for ideal emitters (of deltalike distribution and zero linewidth) having wavelengths within the spectral range used in the design process. The white circles define the five wavelengths incorporated in the optimization process. The $Q$- value is obtained at the peak half maximum.

Figure 4

Angular dependence of the square of the electric field calculated at a radius of $250a$ from the center of the optimized LE-SOE (see Fig. 2).