An Ultracompact Directional Coupler Based on GaAs Cross-Slot Waveguide

Passive technologies for future large-scale photonic integrated circuits on silicon: polarization handling, light non-reciprocity and loss reduction

“…Several kinds of waveguide type PBSs have been reported by using various structures, e.g., Mach-Zehnder interferometers (MZIs), 30,31 multimode interference (MMI) structure, [32][33][34][35] directional couplers (DCs) [36][37][38][39][40][41] and photonic crystal (PhC)/grating structures. 42,43 For the conventional MMI-based PBS, the MMI length is usually chosen as the common multiple of the beat lengths for transverse electric (TE) and transverse magnetic (TM) polarizations.…”

A compact plasmonic MOS-based 2×2 electro-optic switch

“…An interesting finding is that the insertion loss can be about 1-2 dB only; this is not only about an order of magnitude lower compare to~19.8 dB insertion loss obtained by a directional coupler structure [4], but also states that plasmonics is not necessarily a high-loss technology [35]. This denotes that plasmonics can be strategically used to enhance the LMI, if synergistically integrated in passive data routing (i.e.…”

“…An important building block for network-on-chip architectures is the 2×2 crossbar switch, a device with two inputs and outputs whereas the optical routing is controlled by an electrical gate. A variety of photonic switches have been investigate such as those based on directional couplers (DC) [2][3][4], multimode interference (MMI) [5,6], ring resonators, Mach-Zehnder interferometers (MZI) [7,8] and photonic-crystal-based (PhC) structures [9][10][11]. While these approaches are able to reduce the footprint into the ten's of micrometer scale for instance by deploying high-Q ring resonators, they introduce other limitations relating to bandwidths (spectrally and temporally) and demand tighter fabrication tolerances for mode-coupled devices [12,13].…”

Silicon-based on-chip multiplexing technologies and devices for Peta-bit optical interconnects

“…It has been realized that most photonic integrated devices are polarization dependent due to the birefringence of optical waveguides (as summarized in Table 2), which provides various ways to realize waveguide-type PBSs, including multimode interferometers (MMIs) [106][107][108][109][110], DCs [111][112][113][114][115][116][117][118], MZIs [119][120][121], photonic crystal (PhC) structures [122][123][124][125][126], AWGs [127], MRRs [128], etc. Among them, a DC structure is an attractive option for PBSs because of its structural simplicity.…”

“…The beat length L π MZI [119][120][121] The central wavelengths DC [111][112][113][114][115][116][117][118] The coupling length/the coupling ratio PhC/Grating [122][123][124][125][126] The bandgap (reflection/transmission) AWG [127] The central wavelengths (@ x = x o ) The imaging position (@λ = λ 0 ) MRR [128] The resonance wavelength Figure 16 The cross section of the two waveguides for an asymmetrical coupling system.…”