We report a very compact (1.6μmx10μm) and low dark current (20nA) Germanium p-i-n photodetector integrated on
0.25μm thick silicon-on-insulator (SOI) waveguides. A thin layer of Germanium was selective-epitaxially grown on top
of SOI waveguides. Light is evanescently coupled into Germanium layer from the bottom SOI waveguide. The device
demonstrates superior performance with demonstrated responsivity of 0.9A/W and 0.56A/W at wavelength of 1300nm
and 1550nm, respectively, and dark current less than 20nA at -0.5V bias. The 3dB bandwidth of the device is measured
to be 23GHz at -0.5V bias.
A Si ridge waveguide integrated with a lateral p-i-n diode forms a basic optical amplitude
and phase modulator. An efficient Si modulator is expected to establish a carrier concentration in
the waveguide with a minimum amount of electrical drive power.
We show that P<sup>+</sup> and N<sup>+</sup> doping sections that are recessed below the slab lead to lower power
consumption. This configuration is compared with alternative doping section arrangements. The
optimum arrangement results in less Si active area and reduced carrier recombination.
Effective carrier lifetimes of Si modulators based upon a lateral p-<i>i</i>-n structure were measured using
the reverse-recovery method. Modulators of two different waveguide dimensions were
characterized using this approach. Two additional lifetime measurement methods were used to
check against this method and showed consistent results. Finally the physical meaning of this
measured effective carrier lifetime was discussed in reference to its relationship with the diode
transit time, surface recombination velocity and the bulk carrier lifetime.
While investment in sub-wavelength silicon photonics research has gained popularity, Kotura has forged significant
customer traction with first generation silicon-photonics products by focusing on manufacturable designs and processes.
This paper reviews recent gains in engineering developments where mature monolithic and hybrid methods are
integrated to form high-performance manufacturable products with proven long-term reliability. Components and
methods are described that lead to photonic modules and subsystems suitable for automated manufacturing techniques.
We report the design of a 10 GHz non-return-to-zero (NRZ) silicon modulator based upon 0.25-μm CMOS/BiCMOS processes. The basic optical component is a ridge waveguide slightly-doped with P and N impurities, which forms a reverse-biased P/N junction. The diode typically operates between reverse and zero biases, so as to change the number of free carriers overlapping with the optical mode and consequently modulate the phase of the light. This type of phase shifters form the arms of a push-pull Mach-Zehnder interferometer to realize amplitude modulation.