Thermo-optically tunable silicon photonic crystal light modulator

Abstract

We designed, fabricated, and characterized a thermo-optically tunable compact (10 μm × 10 μm) silicon photonic crystal (PhC) light modulator that operates at around 1.55 µm for TE polarization. The operational principle of the device is the modulation of the cutoff frequency in a silicon-based line defect PhC. The cutoff frequency is shifted because of the thermo-optic tuning of the silicon refractive index, which is realized by localized heating on the PhC. The modulator is formed by a triangular lattice array of cylindrical air holes on a silicon-on-insulator wafer. Optical characterization was carried out, and the result clearly showed thermo-optic tuning of the cutoff frequency at around 1.55 µm.

Indium-Tin-Oxide for High-performance Electro-optic Modulation

“…The thermo-optic effect results from a temperature dependent refractive index of a material, [33]. Another widely used thermo-optic effect material is polymer, which has the advantages of low density and refractive index, less dispersion, cheap manufacturing cost, easy to make complex shapes, and good electrical insulation.…”

Thermo-optic switch based on transmission-dip shifting in a double-slot photonic crystal waveguide

“…16 The reported extinction ratio for the switch with cutoff effect in PCWG is just about $0.42 ($3.8 dB) while the applied current is 70 mA. 15 In this paper, we experimentally demonstrate a different operating principle for PCWG switches by the unique coupling between the defect modes in PBG, which is realized by our previously proposed double-slot photonic crystal waveguide (DS-PCWG). 17 The DS-PCWG is formed by introducing two slots into a W3 PCWG (a line-defect PCWG with three rows of holes missing).…”

“…The other one is based on the cutoff effect in a single PCWG. 14,15 Around the cutoff frequency at the edge of photonic band gap (PBG), there is an abrupt drop of the light transmission. By shifting the transmission dip, optical switch could be obtained.…”

“…By shifting the transmission-dip, the TO switching phenomenon is observed by the fabricated DS-PCWG with a length of 16 lm and covered with titanium (Ti)/aluminum (Al) microheater. Compared with the PCWG used cut-off effect to realize switching functionality, typically W1 PCWG, 14,15 the width of DS-PCWG is enlarged so that the coupling efficiency can be improved while a simple and compact structure could still be obtained. According to the experimental results, extinction ratio of 17 dB and switching power of 9.2 mW are achieved.…”

Ultra-compact variable optical attenuator based on slow light photonic crystal waveguide

“…The third way is to utilize the cutoff effect of a single PCWG, which provides a simple platform for compact devices with less complex structure designs. Tinker et al [12,13] theoretically analyzed the realization of the tunable single PCWG by thermo-optical effect, demonstrating a PCWG modulator with the cutoff effect. Wang et al theoretically modeled the mechanism of the cutoff effect to realize a switch using a single PCWG [14] .…”