arXiv subjects

Michal Lipson

Publications and source records attributed to Michal Lipson.

97 records · Page 6Linked to original sources

arXiv2009

CMOS compatible athermal silicon microring resonators

Silicon photonics promises to alleviate the bandwidth bottleneck of modern day computing systems. But silicon photonic devices have the fundamental problem of being highly sensitive to ambient temperature fluctuations due to the high thermo-optic (TO) coefficient of silicon. Most of the approaches proposed to date to overcome this problem either require significant power consumption or incorporate materials which are not CMOS-compatible. Here we demonstrate a new class of optical devices which are passively temperature compensated, based on tailoring the optical mode confinement in silicon waveguides. We demonstrate the operation of a silicon photonic resonator over very wide temperature range of greater than 80 degrees. The fundamental principle behind this work can be extended to other photonic structures such as modulators, routers, switches and filters.

physics.optics↗

arXiv2009

Stimulated emission in erbium doped silicon rich nitride waveguides

Stimulated emission of sensitized Erbium atoms is reported in silicon-rich silicon nitride waveguides. Visible pump and infrared probe measurements are carried out in waveguides fabricated from erbium-doped silicon rich silicon nitride. A decrease in the photoinduced absorption of the probe in the wavelength range of the erbium emission is observed and is attributed to stimulated emission from erbium atoms excited indirectly via the silicon excess in an SiNx matrix. A near 50% decrease in absorption is measured, corresponding to an 8% fraction of inverted erbium atoms. This fraction is an order of magnitude higher than that obtained in counterpart oxide systems possessing observable nanocrystals. Our results indicate that population inversion and gain at 1.54 um might be possible by optimizing the silicon excess in the SiNx matrix.

physics.optics↗

arXiv2009

Silicon nanostructure cloak operating at optical frequencies

The ability to render objects invisible using a cloak - not detectable by an external observer - for concealing objects has been a tantalizing goal1-6. Here, we demonstrate a cloak operating in the near infrared at a wavelength of 1550 nm. The cloak conceals a deformation on a flat reflecting surface, under which an object can be hidden. The device has an area of 225 um2 and hides a region of 1.6 um2. It is composed of nanometre size silicon structures with spatially varying densities across the cloak. The density variation is defined using transformation optics to define the effective index distribution of the cloak.

physics.optics↗

arXiv2009

Monolithically integrated multiple wavelength oscillator on silicon

Silicon photonics enables on-chip ultra-high bandwidth optical communications networks which is critical for the future of microelectronics1,2. By encoding information on-chip using multiple wavelength channels through the process of wavelength division multiplexing (WDM), communication bandwidths in excess of 1 Tbit s-1 are possible3. Already several optical components critical to WDM networks have been demonstrated in silicon, however a fully integrated multiple wavelength source capable of driving such a network has not yet been realized. Optical amplification, a necessary component for producing a source, can be achieved in silicon through stimulated Raman scattering4,5, parametric mixing6, and the use of silicon nanocrystals7 or nanopatterned silicon8. Losses in most of these previously demonstrated devices have prevented oscillations in those structures. Raman oscillators have been demonstrated9-11, but the narrow Raman gain window limits operation to a tightly restricted (~ 1 nm) wavelength range and thus is insufficient for WDM. Losses in other previously demonstrated devices have prevented oscillations in those structures. Here we demonstrate the first monolithically integrated CMOS-compatible multiple wavelength source by creating an optical parametric oscillator (OPO) formed by a silicon nitride ring resonator on silicon coupled to an integrated waveguide. The device can generate more than 100 new wavelengths, spaced by a few nm, with operating powers below 50 mW. This source can form the backbone of a fully operational high-bandwidth optical communications network on a microelectronic chip enabling the next generation of multi-core microprocessors.

physics.optics↗

arXiv2009

Integrated GHz silicon photonic interconnect with micrometer-scale modulators and detectors

We report an optical link on silicon using micrometer-scale ring-resonator enhanced silicon modulators and waveguide-integrated germanium photodetectors. We show 3 Gbps operation of the link with 0.5 V modulator voltage swing and 1.0 V detector bias. The total energy consumption for such a link is estimated to be ~120 fJ/bit. Such compact and low power monolithic link is an essential step towards large-scale on-chip optical interconnects for future microprocessors.

physics.optics↗

arXiv2009

Controlling photonic structures using optical forces

The downscaling of optical systems to the micro and nano-scale results in very compliant systems with nanogram-scale masses, which renders them susceptible to optical forces. Here we show a specially designed resonant structure for enabling efficient static control of the optical response with relatively weak repulsive and attractive optical forces. Using attractive gradient optical forces we demonstrate a static mechanical deformation of up to 20 nanometers in the resonator structure. This deformation is enough to shift the optical resonances by roughly 80 optical linewidths.

physics.optics↗

arXiv2008

Telecom-Band Entanglement Generation for Chipscale Quantum Processing

We demonstrate polarization-entanglement for non-degenerate and degenerate photon-pairs generated through Kerr-nonlinearity in a nano-scale silicon-on-insulator(SOI) waveguide. We use a compact counter propagating configuration to create two-photon polarization-entangled state, |H>|H> + |V>|V>. We observe two-photon interference with visibility > 91% and > 80% for non-degenerate and degenerate photon-pairs, respectively. The experimental structure can be implemented on optical chips as an integrated source of entangled photons for future quantum computer and communication applications.

quant-ph↗