Electroabsorption Modulator Schemes Based on Uniaxial Tensioned Germanium / Silicon Germanium Multiple Quantum Wells

Due to the serious power consumption and bandwidth constraints of the development of large scale integrated circuits, on-chip interconnection has been considered as a potential development path. Silicon photonics is the most suitable platform for integrating optics and electronics, but is constrained by active devices. Germanium and silicon germanium alloy materials have received more and more attention recently. This is due to the fact that the direct bandgap energy of germanium corresponds to a wavelength in the C band, whereas the indirect bandgap L valley edge is only 140 eV below the direct bandgap Γ valley. Researchers have proposed and developed various CMOS-compatible methods to change the band structure of germanium-related materials, including germanium / silicon germanium quantum wells, vacant germanium microstructures, and germanium-tin alloys. In the silicon-based modulator field, Germanium / silicon germanium quantum well electro-absorption modulator has the advantages of small size and low power consumption. Due to the quantum confinement effect, the direct bandgap absorption energy of the germanium / silicon germanium quantum well is larger than that of the germanium material. The previous 10 nm wide germanium quantum well operates at zero bias voltage at 1420 nm. Although the absorption edge can be regulated by applying a different bias voltage, the absorption contrast also deteriorates with increasing bias voltage. Higher bias voltage is not suitable for large-scale integration. Thus, the operating wavelength of germanium / silicon germanium multiple quantum well electroabsorption modulator is limited.

Wuhan Optoelectronics National Laboratory Optoelectronic Devices and Integrated Functional Laboratory Professor Sun Junqiang lead doctoral students such as Gao Jian-feng proposed a uniaxial tensile strained germanium / silicon germanium multi-quantum well electroabsorption modulator scheme. The scheme greatly broadens the working wavelength range of the electroabsorption modulator of the germanium / silicon germanium multi-quantum well, and can improve the absorption contrast of the TE mode. By introducing a uniaxial tensile strain of 0.18% -1.6%, a zero-bias electroabsorption modulator covering a wavelength range of 1380-1550 nm can be fabricated on a 10/12 nm Ge / Si 0.19 Ge 0.81 chip. For waveguide applications, uniaxial tensile strain germanium / silicon germanium quantum wells have enhanced TE absorption contrast and suppressed TM absorption. At 1.6% uniaxial tensile strain and 0V / 2V operating voltage, the TE absorption contrast was increased by 3.1 dB and the TM absorption coefficient was reduced by two thirds. The enhanced TE absorption contrast and wide operating wavelength range make the device ideal for waveguide integration and high-efficiency modulation applications.

The research result "Design and analysis of electro-absorbing modulators with uniaxially stressed Ge / SiGe multiple quantum wells", published May 2, 2017, is published in OSA's Journal Optics Express (Vol.25, No.10, pp. , 2017) magazine. The research was funded by the National Natural Science Foundation of China (61435004).

(A) Ge / SiGe multiple quantum well structure. (B) Schematic diagram of the structure of an electroabsorption modulator based on a suspended micro-bridge. (C) Stereo tensor εxx distribution. (D) The xy plane strain tensor εxx (E) Mode field component Ey distribution of quasi-TE fundamental mode at 1550 nm wavelength.

The jet water pipe is part of Trailing Suction Hopper Dredger, work together with Suction Pipe, through suction pipe, from the seabed dredging ship, the dredging method is similar to a vacuum cleaner. Ship fitted with one or several pumps, centrifugal pumps suck up water from the sea floor and mud, into the hopper of the ship. These operations are carried out during the voyage , while digging edge flight, heading for the hopper filled to throw mud mud area, through the mud bilge cases out the door. shiploads are trailing suction hopper with its capacity to indicate the size specifications, the general compartment volume is 500 ~ 1000m3. the minimum energy of trailing suction boat under construction in water depths of about 3 conditions deepened the largest trailing suction ship up to 3 to 35 or more. this ship belongs to the trailing suction ship, dredging can be considerable in the storm at sea, navigation and throwing mud. The Jet Pipe can clean the dirty material from sea

Basic introduction

Any pipeline used to make the gas flow down the growth rate is called the nozzle, there are two kinds of commonly used in thermal power nozzle: one is the gradual shrink nozzle, the other is a convergent divergent nozzle, or Lawal nozzle.

In the jet engine, high pressure gas (or air) is converted into kinetic energy, so that the air flow in which the expansion of the acceleration of high speed outward jet to produce the reverse thrust of the component, also known as exhaust nozzle, thrust nozzle or tail nozzle. There are many types of nozzle, such as fixed or adjustable convergent divergent nozzle, convergent divergent nozzle, ejector nozzle and plug nozzle. High-speed fighter mostly adopts adjustable convergent nozzle and adjustable convergence diffusion nozzle and ejector nozzle; rocket engine fixed convergent divergent nozzle; vertical or short takeoff and landing aircraft by converting nozzle.

The ratio of total pressure at the inlet of the nozzle and the static pressure at the outlet is called the nozzle pressure ratio, the expansion ratio or the pressure ratio. Convergent divergent nozzle exit area and critical section area (the minimum cross section area of over expansion area ratio, known as the area ratio of the nozzle. When the gas stream is expanded to the static pressure of the nozzle exit exactly equal to the atmospheric pressure, known as fully expanded nozzle, its performance best when the flow in the nozzle exit static pressure is greater than the outside atmospheric pressure, said is not fully expanded nozzle, the pressure of the gas flow can not fully converted to kinetic energy. When the static pressure at the nozzle exit is lower than that of the external pressure, it is called the over expansion nozzle.

Photo of our Jet pipe:

Jet Pipe

Steel Jet Pipe,Steel Water Jet Pipe,Water Jet Pipe,Jet Pipe Steel

Unisite Group Ltd. , https://www.shipsparts.nl