All-Optical Frequency Shifting - Optical Signal Processing by Silicon Photonics - page 87

Fig. 7.6 Silicon resonant structure [ 39 ]
structure is to be incorporated and biased to sweep out free carriers from the opti-
cal waveguide generated in response to TPA in the optical waveguide [ 41 ].
Stimulated Raman scattering (SRS) effect at infrared frequencies was discovered
in 1962 and TPA process with a full quantum mechanical calculation was described
afterwards to account for anti-Stokes generation and higher order Raman effects,
while coupled-wave formalism was adopted to describe the stimulated Raman-
effect. Self-focusing was later included to give a reason for the much larger gain
observed in SRS which facilitated the study and design of Raman amplifiers and
lasers. The Trustees of Columbia University patented their design in [ 42 , 43 ].
There is an increasing demand for tunable lasers fueled by the advent of WDM
which has become widespread in fiber optic communication systems. In [ 44 ]
Light wire formed an SOI based tunable laser, consisting of a tunable wavelength
reflecting element and associated phase matching elements, these are formed on
the surface of the SOI structure, with optical waveguides shaped in the SOI sur-
face layer providing communication between these components. The tunable
wavelength element is controlled to adjust the optical wavelength. Macquarie
University, New South Wales patented the design of an optical amplifier laser [ 45 ],
on a similar principle.
7.6 Optical Parametric Amplifier
An optical parametric amplifier, abbreviated as OPA, is a laser light source that
emits light of variable wavelengths by an optical parametric amplification (OPA)
process.