InGaAsP Membrane Research Articles

Lasing Action from Anapole Metasurfaces.

We study active dielectric metasurfaces composed of two-dimensional arrays of split-nanodisk resonators fabricated in InGaAsP membranes with embedded quantum wells. Depending on the geometric parameters, such split-nanodisk resonators can operate in the optical anapole regime originating from an overlap of the electric dipole and toroidal dipole Mie-resonant optical modes, thus supporting strongly localized fields and high-Q resonances. We demonstrate room-temperature lasing from the anapole lattices of engineered active metasurfaces with low threshold and high coherence.

III–V/Si Hybrid MOS Optical Phase Shifter for Si Photonic Integrated Circuits

We present a novel optical phase modulation scheme on a Si photonic platform that uses a III–V/Si hybrid metal–oxide–semiconductor (MOS) capacitor formed by bonding an n-type InGaAsP membrane on a p-type Si waveguide. We numerically revealed that the phase modulation efficiency was improved by a factor of 7–8 owing to electron accumulation at the InGaAsP MOS interface when the n-type Si layer in a Si MOS optical phase shifter was replaced by an n-type InGaAsP layer. To realize the III–V/Si hybrid MOS capacitor, we developed an Al2O3 bonding interface deposited by atomic layer deposition that enabled a low interface trap density of μ m wavelength owing to the electron-induced change in the refractive index of InGaAsP. Since no holes were induced in the III–V layer of the III–V/Si hybrid MOS capacitor, we avoided large hole-induced absorption in InGaAsP. As a result, when we had a π phase shift, we obtained optical absorption of 0.23 dB, approximately ten times smaller than that of a Si MOS optical phase shifter. We found by numerical analysis that the efficient low-loss III–V/Si hybrid MOS optical phase shifter improved markedly the optical modulation amplitude, indicating its suitability for high-speed modulation beyond 100 Gb/s. We also demonstrated a Mach–Zehnder interferometer optical switch using the proposed optical phase shifter with a switching time of less than 20 ns. We achieved an extremely low switching power of approximately 1 nW, enabling a large-scale optical switch and universal photonic integrated circuits. We also discuss the feasibility of a photonic neural network for deep learning.

Thermal analysis of line-defect photonic crystal lasers.

We report a systematic study of thermal effects in photonic crystal membrane lasers based on line-defect cavities. Two material platforms, InGaAsP and InP, are investigated experimentally and numerically. Lasers with quantum dot layers embedded in an InP membrane exhibit lasing at room temperature under CW optical pumping, whereas InGaAsP membranes only lase under pulsed conditions. By varying the duty cycle of the pump beam, we quantify the heating induced by optical pumping in the two material platforms and compare their thermal properties. Full 3D finite element simulations show the spatial temperature profile and are in good agreement with the experimental results concerning the thermal tolerance of the two platforms.

Multimodal strong coupling of photonic crystal cavities of dissimilar size

A photonic crystal three missing holes nanocavity, having only a few modes, is coupled to a 60 missing holes long multimode cavity, both fabricated in the same InGaAsP membrane. The coupling was studied in detail by the photothermal tuning of the small cavity over about three free spectral ranges of the large cavity. Strong coupling effects, involving at least three large cavity modes simultaneously, were observed from level anticrossing data. The observations are excellently reproduced by a model of coupled Fabry Perot resonators.

Hybrid Integration of Photonic Crystal Membrane Lasers via Postprocess Bonding

Photonic crystal (PhC) lasers in InGaAsP membranes are bonded after fabrication to a sapphire substrate. The processed devices are held to the sapphire by van der Waals forces and do not require a high temperature anneal. PhC H2 defect cavity devices are found to lase continuous wave and line defect heterostructure devices lase pulsed, both under optical excitation. Postprocess bonding allows extensive fabrication on the native substrate before being transferred to a new substrate, which may be useful for making more complex nanophotonic devices and/or electrically injected devices.

Electromechanical wavelength tuning of double-membrane photonic crystal cavities

We present a method for tuning the resonant wavelength of photonic crystal cavities (PCCs) around 1.55 μm. Large tuning of the PCC mode is enabled by electromechanically controlling the separation between two parallel InGaAsP membranes. A fabrication method to avoid sticking between the membranes is discussed. Reversible red/blueshifting of the symmetric/antisymmetric modes has been observed, which provides clear evidence of the electromechanical tuning, and a maximum shift of 10 nm with <6 V applied bias has been obtained.

Controlling mode degeneracy in a photonic crystal nanocavity with infiltrated liquid crystal

We demonstrate the control of the mode degeneracy when a liquid crystal (LC) is infiltrated into an InGaAsP membrane photonic crystal nanocavity with embedded InAs quantum dots. Mode splitting exists in the anisotropic nematic LC state, and not in the unfilled or isotropic LC state. The degeneracy lifting of the quadrupole mode is attributed to the different interactions of the two orthogonal basis modes of the degenerate mode with the two components of the refractive index of the LC. The interpretation is supported by the quantitative agreement between the experimental results and the three-dimensional finite-difference time-domain computations.

Efficient Membrane Grating Couplers on InP

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> We demonstrate an efficient coupler on InP using an etched grating on a suspended InGaAsP membrane. We measure a peak coupling efficiency of 40% (<formula formulatype="inline"><tex Notation="TeX">$-$</tex></formula>4 dB) between a cleaved standard single-mode fiber and a conventional nonsuspended InGaAsP waveguide with a 3-dB bandwidth of <formula formulatype="inline"> <tex Notation="TeX">$\sim$</tex></formula>45 nm. </para>

Lithographic and optical tuning of InGaAsP membrane photonic crystal nanocavities with embedded InAs quantum dots

Hexagonal symmetry InGaAsP membrane type cavities with embedded InAs quantum dots as active emitters were investigated by room temperature photoluminescence experiments at wavelengths near 1.50 µm. Cavities consisting of simple defects of just removing one or seven air holes were studied as well as modified cavities with additional holes decreased in size and shifted in position. The latter include the H0 cavity, in which only two adjacent holes were modified, but none removed. Low-Q cavity modes were observed for the simple cavities while high-Q modes were observed after modification of the surrounding holes. The resonant frequencies were varied over a large range of lithographic parameters both by changing the lattice spacing or the size of the modified holes. More than 15 nm reversible dynamic optical tuning of the resonance modes was observed by changing the applied laser power up to 5 mW. For thermo-optic tuning, this corresponds to a heating of up to 200 °C.

Modified spontaneous emission from laterally injected photonic crystal emitter

The first use of lateral current injection to excite membrane photonic crystal light emitters is reported. The devices utilise a transverse diode that is created via ion implantation into a 280 nm-thick InGaAsP membrane. Photonic bandgap effects and spectral tuning of the electroluminescence spectra due to the graphene geometry photonic crystal are presented.

Photonic crystal lasers in InGaAsP on a SiO2/Si substrates and its thermal impedance

Two-dimensional photonic crystal defect lasers in InGaAsP membranes directly bonded to a SiO(2)/Si substrate have been demonstrated. Lasing at wavelengths near 1550 nm was obtained with incident threshold pump powers as low as 1.5 mW. Good agreement between experimental data and three-dimensional finite-difference time-domain (FDTD) simulation was achieved. The thermal impedance of this laser is also characterized.