A sub-micron depletion-type photonic modulator in Silicon On Insulator

Abstract

We provide detailed analysis of a four terminal p+pnn+ optical modulator integrated into a silicon-on-insulator (SOI) rib waveguide. The proposed depletion device has been designed to approach birefringence free operation. The modulation mechanism is the carrier depletion effect in a pn junction; carrier losses induced are minimised in our design and because we use a depletion device, the device is insensitive to carrier lifetime. The rise time and fall time of the proposed device have both been calculated to be 7 ps for a reverse bias of only 5 volts. A maximum excess loss of 2 dB is predicted for TE and TM due to the presence of p type and n type carriers in the waveguide.

Recent breakthroughs in carrier depletion based silicon optical modulators

“…The first proposed [18] and demonstrated [19] waveguide based carrier depletion modulators were of this type. The simulated performance by Gardes et al [18] carrier depletion devices, which was a break through at that time [18]. Two years later the Intel Corporation demonstrated this version of the device experimentally with modulation at 30 Gbit/s presented [19].…”

Fabrication of depletion type micro-ring modulator with high extinction ratio and high coupling quality factor

“…The main method is altering the refractive index of Silicon, which is based on thermo-optic effect or plasma dispersion effect [4]. The thermo-optic effect is too slow to realize modulation frequencies higher than 1-MHz [8]. Thus, the plasma dispersion effect is considered as the most effective way of refraction index modulation in silicon [4].…”

Addressing Fiber-to-Chip Coupling Issues in Silicon Photonics

“…The strong light confinement in SOI, given by the high index contrast between silicon core (n = 3.48 at λ = 1550nm) and silicon dioxide (SiO 2 ) (n = 1.45 at λ = 1550nm), makes it feasible to scale photonic devices to the hundreds of nanometer level. Moreover, it is possible to reduce the minimum bending radius radii can improve the characteristics of basic photonic devices such as modulators and optical filters [13,14]. Moreover, such small waveguides can realise an ultra-high optical power density, which can be as much as 1000 times that in a conventional singlemode fiber, enhancing nonlinear optical effects in chipscale devices [15].…”

“…The electronic circuit (11) for processing and distributing the electrical signals to the photonic circuits is placed on top of the carrier. Then, electronic an photonic circuits are wire bonded (12,13) to the FLEX, thus making easier the bonding, as there is no need to bond in the corners of the sub mount carrier due to the presence of the FLEX. seen as the sides of the sub mount carrier (1) are slightly tilted depending on the coupling angle of the resonant vertical fiber coupling technique of the photonic circuits (2,3).…”

“…The electronic circuit (11) which drives electrical signals to the photonic circuits is placed on the top of the carrier. By using the FLEX, the electrical connections of all the circuits can be first wire bonded (12,13) to the flexible layer and then attach the flexible layer containing the circuits to the carrier, thus avoiding an out of plane wire bonding, which would be much more complicated, especially because of the high slopped corners of the carrier. The fiber arrays (4,5) holding the optical fibers can then be aligned and attached to the sub mount carrier containing all the circuits electrically interconnected through the FLEX underneath.…”