Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userOn-chip polarization rotator for type I second harmonic generation
323
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We demonstrate a polarization rotator integrated at the output of a GaAs waveguide producing type I second harmonic generation (SHG). Form-birefringent phase matching between the pump fundamental transverse electric (TE) mode near 2.0 $mu$m wavelength and the signal fundamental transverse magnetic (TM) mode efficiently generates light at 1.0 $mu$m wavelength. A SiN waveguide layer is integrated with the SHG device to form a multi-functional photonic integrated circuit. The polarization rotator couples light between the two layers and rotates the polarization from TM to TE or from TE to TM. With a TE-polarized 2.0 $mu$m pump, type I SHG is demonstrated with the signal rotated to TE polarization. Passive transmission near 1.0 $mu$m wavelength shows ~80 % polarization rotation across a broad bandwidth of ~100 nm. By rotating the signal polarization to match that of the pump, this SHG device demonstrates a critical component of an integrated self-referenced octave-spanning frequency comb. This device is expected to provide crucial functionality as part of a fully integrated optical frequency synthesizer with resolution of less than one part in 10$^{14}$.
rate research
Read More
Nonlinear frequency conversion plays a crucial role in advancing the functionality of next-generation optical systems. Portable metrology references and quantum networks will demand highly efficient second-order nonlinear devices, and the intense nonlinear interactions of nanophotonic waveguides can be leveraged to meet these requirements. Here we demonstrate second harmonic generation (SHG) in GaAs-on-insulator waveguides with unprecedented efficiency of 40 W$^{-1}$ for a single-pass device. This result is achieved by minimizing the propagation loss and optimizing phase-matching. We investigate surface-state absorption and design the waveguide geometry for modal phase-matching with tolerance to fabrication variation. A 2.0 $mu$m pump is converted to a 1.0 $mu$m signal in a length of 2.9 mm with a wide signal bandwidth of 148 GHz. Tunable and efficient operation is demonstrated over a temperature range of 45 $^{circ}$C with a slope of 0.24 nm/$^{circ}$C. Wafer-bonding between GaAs and SiO$_2$ is optimized to minimize waveguide loss, and the devices are fabricated on 76 mm wafers with high uniformity. We expect this device to enable fully integrated self-referenced frequency combs and high-rate entangled photon pair generation.
We report second harmonic generation from a titanium indiffused lithium niobate waveguide resonator device whose cavity length is locked to the fundamental pump laser using an on-chip phase modulator. The device remains locked for more than 5 minutes, producing more than 80% of the initial second harmonic power. The stability of the system is seen to be limited by DC-drift, a known effect in many lithium niobate systems that include deposited electrodes. The presented device explores the suitability of waveguide resonators in this platform for use in larger integrated networks.
We report the observations of unexpected layer-dependent, strong, and anisotropic second harmonic generations (SHGs) in atomically thin ReS2. Appreciable (negligible) SHGs are obtained from even (odd) numbers of ReS2 layers, which is opposite to the layer-dependence of SHGs in group VI transition metal dichalcogenides, such as MoS2 and WS2. The results are analyzed from ReS2s crystal structure, implying second harmonic polarizations generated from the interlayer coupling. Pumped by a telecomband laser, SHG from the bilayer ReS2 is almost one order of magnitude larger than that from the monolayer WS2. The estimated second-order nonlinear susceptibility of 900 pm/V is remarkably high among those reported in two-dimensional materials. The laser polarization dependence of ReS2s SHG is strongly anisotropic and indicates its distorted lattice structure with more unequal and non-zero second-order susceptibility elements.
Second harmonic generation (SHG), as one of the most significant c{hi}(2) nonlinear optical processes, plays crucial roles in a broad variety of optical and photonic applications. Designing various delicate schemes to achieve highly efficient SHG has become a long standing and challenging topic in field of nonlinear optics. Despite numerous success on SHG based on birefringent phase matching and quasi-phase matching, so far, modal phase matching (MPM) for SHG in tightly light-confined structures has still in its infancy. Here, we propose a new scheme to realize highly-efficient SHG via MPM by using a nanophotonic LiNbO3 thin-film waveguide consists of two bonded layers with internally reversed polarizations. In such a dual-layer ridge waveguide based on lithium niobate on insulator, upon optical excitation at 1574.6 nm, we observe SHG at 787.3 nm with ultrahigh conversion efficiency of 5,540% /W/cm/cm experimentally. This work advances our understanding on modal-phase-matched SHG and other quadratic optical nonlinear process, offering additional strategies for development of high-performance nonlinear photonic devices in on-chip platforms.
Second-harmonic generation (SHG) is a direct measure of the strength of second-order nonlinear optical effects, which also include frequency mixing and parametric oscillations. Natural and artificial materials with broken center-of-inversion symmetry in their unit cell display high SHG efficiency, however the silicon-foundry compatible group-IV semiconductors (Si, Ge) are centrosymmetric, thereby preventing full integration of second-order nonlinearity in silicon photonics platforms. Here we demonstrate strong SHG in Ge-rich quantum wells grown on Si wafers. The symmetry breaking is artificially realized with a pair of asymmetric coupled quantum wells (ACQW), in which three of the quantum-confined states are equidistant in energy, resulting in a double resonance for SHG. Laser spectroscopy experiments demonstrate a giant second-order nonlinearity at mid-infrared pump wavelengths between 9 and 12 microns. Leveraging on the strong intersubband dipoles, the nonlinear susceptibility almost reaches 10^5 pm/V
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
