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A monolithic CMOS compatible process has been developed to realize vertically integrated devices in silicon. The method involves the implantation of an oxygen into a patterned silicon substrate to form buried guiding structures. These buried devices are separated from a surface silicon layer by an intervening layer of silicon dioxide formed through the implantation process. Photolithography and etching is used to define devices on the surface silicon layer. The method has been utilized to realize the vertically coupled microdisk resonators and a variety of microresonator-based integrated optical elements. A new method for extraction of the unloaded Q of a cavity from its measured spectrum is also described.

A modified separation by implantation of oxygen process has been developed to sculpt vertically coupled microdisk resonators in silicon. The approach involves the implantation of oxygen ions into a silicon substrate, patterned with thermal oxide, to define waveguides on the bottom silicon layer, and photolithography and reactive ion etching to define the microdisk resonators on the top silicon layer. The top and the bottom silicon layers are separated by the oxide layer that was formed after the oxygen implantation. Fabricated microdisk resonators show resonances with a Q value of 10 300 and a free spectral range of 5.4nm.

Stimulated supercontinuum generation via coherent seeding is numerically demonstrated to produce continua of broader bandwidth and higher coherence than the conventional unseeded case. Implications for energy efficient generation of WDM channels are discussed.

Nonlinear losses limit supercontinuum efficiency in silicon. This fundamental limitation can be relaxed and higher energy efficiency and a more stable output can be obtained by stimulating modulation instability with an off-resonant weak seed.

We describe our recent achievements in the integration of narrowband photonic RF receivers and discuss their ultimate performance parameters. The best sensitivity and the spurious free dynamic range achieved in the current built of our coherent receiver approaches −145 dBm/Hz and 90 dB/Hz2/3 respectively. We plan to improve these values to −164 dBm/Hz and 105 dB/Hz2/3 in the next generation receivers, while keeping the 13.5×8.5×4.7 mm form factor intact.

This talk will review recent progress in our laboratory Raman amplification in silicon, including the achievable noise figure and gain, creating broadband gain, inverse Raman scattering phenomenon, and extreme value fluctuations.

Broadband coherent antistokes Raman scattering (CARS) is observed experimentally in silicon, facilitated by self‐phase modulation induced spectral broadening of the pump. Numerical modeling reveals the strong influence of free carrier dynamics on the CARS process.

Stimulated Raman scattering has been harnessed to produce the first silicon lasers and amplifiers. The Raman effect can also produce intensity-dependent nonlinear loss through a corollary process, inverse Raman scattering (IRS). This process has never been observed in a semiconductor. We demonstrate IRS in silicon---a process that is substantially modified by optically generated free carriers---achieving attenuation levels $g15\text{ }\text{dB}$ with a pump intensity of $4\text{ }\text{GW}/{\text{cm}}^{2}$. Surprisingly, free-carrier absorption, the detrimental effect that generally suppresses nonlinear effects in silicon, actually facilitates IRS by delaying the onset of contamination from coherent anti-Stokes Raman scattering. Silicon-based IRS could be a valuable tool for chip-scale signal processing.

We experimentally demonstrate unprecedented wavelength conversion efficiency of 58% from coherent anti-Stokes Raman scattering (CARS) in a silicon waveguide. CARS is modeled by incorporating Raman scattering and free carrier effects into the nonlinear Schrodinger equation.

Spectral broadening in silicon is studied numerically as well as experimentally. Temporal dynamics of the free carriers generated during the propagation of optical pulses, through the process of two-photon absorption (TPA), affect the amplitude and phase of the optical pulses, thereby determining the nature and extent of the generated spectral continuum. Experimental results are obtained by propagating pico-second optical pulses in a silicon waveguide for intensities that span two orders of magnitude (1-150 GW/cm2). These results validate the conclusions drawn from numerical simulations that the continuum generation has a self-limiting nature in silicon., Comment: 16 pages, 6 figures

An attempt at creating a multi-wavelength silicon light source is reported. Self phase modulation is used to broaden the spectrum of an off-chip seed pulse. The spectrum is filtered into discrete channels using vertically-coupled microresonators.

The integration of photonics and electronics on a single silicon substrate requires technologies that can add optical functionalities without significantly sacrificing valuable wafer area. To this end, we have developed an innovative fabrication process, called SIMOX 3-D Sculpting, that enables monolithic optoelectronic integration in a manner that does not compromise the economics of CMOS manufacturing. In this technique, photonic devices are realized in subsurface silicon layers that are separated from the surface silicon layer by an intervening SiO2 layer. The surface silicon layer may then be utilized for electronic circuitry. SIMOX 3-D sculpting involves (1) the implantation of oxygen ions into a patterned silicon substrate followed by (2) high temperature anneal to create buried waveguide-based photonic devices. This process has produced subterranean microresonators with unloaded quality factors of 8000 and extinction ratios >20dB. On the surface silicon layers, MOS transistor structures have been fabricated. The small cross-sectional area of the waveguides lends itself to the realization of nonlinear optical devices. We have previously demonstrated spectral broadening and continuum generation in silicon waveguides utilizing Kerr optical nonlinearity. This may be combined with microresonator filters for on-chip supercontiuum generation and spectral carving. The monolithic integration of CMOS circuits and optical modulators with such multi-wavelength sources represent an exciting avenue for silicon photonics.

Three-dimensional optoelectronic integration can be achieved in SOI wafers using the process of SIMOX 3D sculpting. Micro-resonators, with unloaded Q of 8000 and extinction ratio >20 dB, were fabricated in a buried silicon layer and MOS transistor structures were fabricated on the surface silicon layer using a patterned SIMOX process.

Stimulated Raman scattering in SOI waveguides has received significant attention recently with the demonstration of pulsed, continuous wave Raman lasers and high gain Raman amplification. However, the limited bandwidth of the Raman signal in silicon (/spl sim/105GHz) renders this scheme unsuitable for broadband WDM amplification unless multi-pumping scheme is employed. Large pulsed gain and lasing have been reported in GeSi waveguides. The SiGe on SOI platform represents a Raman medium with a flexible gain spectrum.

Three-dimensionally integrated microdisk resonators have been employed to realize Vernier filters in Silicon. Cascaded configuration of vertically-coupled microdisk resonators with dissimilar radii increases the free spectral range of filters from 5.5 nm to 23 nm.

Monolithic integration of photonics and electronics has been achieved in silicon by vertically integrating metal-oxide-semiconductor field-effect transistors and waveguide-coupled microdisk resonators in a double-layer silicon-on-insulator wafer, thus paving the way towards dense three-dimensional optoelectronic integration.

This paper presents recent breakthroughs and applications of Raman based silicon photonics such as silicon Raman amplifiers and lasers. These lasers would extend the wavelength range of III-V laser to mid-IR where important applications such as laser medicine, biochemical sensing, and free space optical communication await the emergence of a practical and low cost laser.

A new process has been developed to create vertically-integrated photonic and optoelectronic circuits in silicon. The approach is the 3-D extension of the SIMOX process where buried SiO2 sections can be selectively created by using oxygen implantation, through a mask, followed by annealing. By controlling the implant energy, dose, mask area and thickness, arbitrary 3-D arrangements of Silicon/SiO2 can be created. The process has been used to create vertically coupled microdisk resonators and add-drop wavelength multiplexers on a silicon wafer.

This paper presents the design and operation of Si and GeSi Raman lasers and amplifiers. Different laser applications in various practical fields are also discussed.

Nonlinear optical devices, with silicon-on-insulator material system as platform for their fabrication are discussed. Third order nonlinearity in silicon offers active functionalities in silicon by taking advantage of the high index contrast and tight beam confinement. Among the third order effects; Raman, Kerr nonlinearity, two-photon absorption are particularly strong

We demonstrate all-optical switching based on cross phase modulation in silicon waveguides. Switching of a 1537 nm CW signal by a pulsed pump at 1560 nm and with extinction of 13 dB is demonstrated.

This paper reports the fabrication and characterization of add-drop filters based on vertically coupled microdisk resonators in silicon. SIMOX 3-D sculpting is the technique used to fabricate monolithically integrated filters based on microdisk resonator structures that show adjacent channel cross talk suppression as high as 15 dB for channels that are separated by 1.5 nm.

In this paper we report the demonstration of vertically coupled microdisk resonator structures on SOI substrates, using the technique of SIMOX 3-D sculpting.

In this paper, fabrication of three dimensionally integrated nano-optical structures in silicon-on-insulator (SOI) substrates using the process of separation by implantation of oxygen (SIMOX) is reported. Buried rib waveguides with lowest ever loss with the SIMOX process, reported with the fabrication of vertically integrated structures using conventional lithography and etching process, demonstrate the capability to sculpt 3-D integrated optical devices.

The polarization state of an optical signal is important for optical communication systems, but standard single mode fibers do not maintain the input polarization state.

Properties of a coupled optoelectronic microwave oscillator are studied theoretically. We find analytical expressions for the steady-state values of the pulse duration, chirp, optical power, and the power of the microwave signal generated in the systems as the function of the parameters of the optical and microwave loops. The analytical expressions are compared with the results of the numerical simulations as well as the experimental data.

Raman gain is a useful nonlinear phenomenon that has made optically pumped silicon lasers and amplifiers a reality. Unfortunately, the bandwidth of Raman gain in silicon is normally rather limited, owing to the narrow Raman linewidths typical of crystalline materials. Here, we report Raman amplification in silicon with a spectrum that is modified by the simultaneous occurrence of self-phase-modulation. This combined nonlinear action produces a broad Raman gain spectrum from a narrowband pump source.

Self-phase modulation is utilized to generate a continuum of wavelengths on a silicon chip. The propagation of near transform-limited, picosecond pulses (3ps) through a micron sized silicon waveguide results in the generation of a spectral continuum. This spectral continuum is then carved by microdisk resonators that are integrated three dimensionally on the same chip, resulting in multiple wavelength channels, with the farthest channel being around 3.1nm away from the center wavelength of the seed pulse. This technique can potentially enable wavelength division multiplexing at the chip level using a single off-chip laser.

Monolithic integration of photonics and electronics has been achieved in silicon by three-dimensionally integrating metal-oxide-semiconductor field-effect transistors and waveguide-coupled microdisk resonators. Implantation of oxygen ions into a silicon-on-insulator substrate with a patterned thermal oxide mask followed by a high temperature anneal was utilized to realize the buried photonic structures. This results in the formation of vertically stacked silicon layers separated from each other by an intervening oxide layer. Transistors are fabricated on the surface silicon by conventional processing techniques. Optical and electronic functionalities are thus separated into two different layers of silicon, paving the way toward dense three-dimensional optoelectronic integration.

Laterally-coupled silicon microresonators are fabricated beneath the surface of a silicon-on-insulator substrate using a modified separation by implantation of an oxygen technique. Implantation of oxygen ions into a substrate with patterned thermal oxide mask was utilized to realize buried waveguiding structures. Microdisk resonators in the buried silicon layer show loaded quality factors of 2000, with extinction ratios in excess of 20dB. The process also results in the formation of a silicon layer on the surface of the wafer that is suitable for the fabrication of electronic devices, thereby paving the way for three-dimensional monolithic integration of electronics and photonics in silicon.

We describe the first observation of spontaneous Raman emission, stimulated amplification, and lasing in a SiGe waveguide. A pulsed optical gain of 16dB and a lasing threshold of 25 W peak pulse power (20 mW average) is observed for a Si1-xGex waveguide with x=7.5%. At the same time, a 40 GHz frequency downshift is observed in the Raman spectrum compared to that of a silicon waveguide. The spectral shift can be attributed to the combination of composition- and strain-induced shift in the optical phonon frequency. The prospect of Germanium-Silicon-on-Oxide as a flexible Raman medium is discussed.