Chapters authored
Technological Challenges for Efficient AlGaAs Nonlinear Sources on Chip
Part of the book: Optoelectronics
Widely Tunable Quantum-Dot Source Around 3 μm
We propose a widely tunable parametric source in the 3 μm range, based on intracavity spontaneous parametric down conversion (SPDC) of a quantum-dot (QD) laser emitting at 1.55 μm into signal and idler modes around 3.11 μm. To compensate for material dispersion, we engineer the laser structure to emit in a higher-order transverse mode of the waveguide. The width of the latter is used as a degree of freedom to reach phase matching in narrow, deeply etched ridges, where the in-plane confinement of the QDs avoids non-radiative sidewall electron-hole recombination. Since this design depends critically on the knowledge of the refractive index of In1−xGaxAsyP1−y lattice matched to InP at wavelengths where no data are available in the literature, we have accurately determined them as a function of wavelength (λ = 1.55, 2.12 and 3 μm) and arsenic molar fraction (y = 0.55, 0.7 and 0.72) with a precision of ±4 × 10−3. A pair of dichroic dielectric mirrors on the waveguide facets is shown to result in a continuous-wave optical parametric oscillator (OPO), with a threshold around 60 mW. Emission is tunable over hundreds of nanometers and expected to achieve mW levels.
Part of the book: Quantum-dot Based Light-emitting Diodes
Widely Tunable Quantum-Well Laser: OPO Diode Around 2 μm Based on a Coupled Waveguide Heterostructure
We present the design of a widely tunable monolithic source on GaAs/AlGaAs. It consists of a quantum-well distributed feedback (DFB) laser vertically coupled with a waveguide engineered for nonlinear frequency conversion. No regrowth or alignment is necessary, and all the structure stems from a single epitaxy step. Light is emitted by the 0.98 μm DFB laser and transmitted to the underlying waveguide by an adiabatic taper, where it can undergo parametric down-conversion, providing signal and idler beams around 2 μm. Transfer rates and tolerances for transfer and conversion efficiency are calculated to be compatible with the tolerances of current fabrication processes. We estimate that an OPO threshold can be reached in the underlying waveguide for a laser emitted power of 20–100 mW, if high-reflectivity distributed Bragg reflectors (DBRs) are used.
Part of the book: Nonlinear Optics