TDI charge-coupled devices: design and applications

Mode-division-multiplexing (MDM) and wavelength-division-multiplexing (WDM) are employed simultaneously in a multimode silicon waveguide to realize on-chip MDM and MDM-WDM transmission. Asymmetric Y-junction MDM multiplexers and demultiplexers are utilized for low coherently suppressed demultiplexed crosstalk at the receiver. We demonstrate aggregate bandwidths of 20 Gb/s and 60 Gb/s for MDM and MDM-WDM on-chip links, respectively, with measured 10−9 BER power penalties between 0.1 dB and 0.7 dB per channel.

A 60 Gb/s MDM-WDM Si photonic link with < 0.7 dB power penalty per channel

Preface 1. Scalar wave equations and diffraction of laser radiation 2. Gaussian modes in optical laser cavities and Gaussian beam optics 3. Guided wave modes and their propagation 4. Guided wave interactions and photonic devices 5. Macroscopic properties of materials from stimulated emission and absorption 6. Solid state and gas laser amplifier and oscillator 7. Semiconductor lasers Index.

https://assets.cambridge.org/97805216/42293/frontmatter/9780521642293_frontmatter.pdf

Principles of Lasers and Optics

A short and broadband silicon asymmetric Y-junction two-mode (de)multiplexer is proposed and simulated. An adiabaticity parameter suitable for high index-contrast silicon waveguides is defined. The fast quasiadiabatic dynamics protocol is used to homogeneously distribute adiabaticity over the device length. This protocol limits the power coupled into the unwanted waveguide eigenmode under a fixed value along the propagation. A 16 μm long mode (de)multiplexer with crosstalk < -34 dB is obtained. Simulations show that the optical bandwidth is as large as 300 nm (1400 nm ~ 1700 nm). The design is also fabrication tolerant.

Short and broadband silicon asymmetric Y-junction two-mode (de)multiplexer using fast quasiadiabatic dynamics

A photonic integrated circuit for mode multiplexing and demultiplexing in a few-mode fiber is presented and demonstrated. Two 10 Gbit/s channels at the same wavelength and polarization are simultaneously transmitted over modes LP01 and LP11a of a few-mode fiber exploiting the integrated mode MUX and DEMUX. The proposed Indium-Phosphide-based circuits have a good coupling efficiency with fiber modes with mode-dependant loss smaller than 1 dB. Measured mode excitation cross-talk is as low as -20 dB and a channel cross-talk after propagation and demultiplexing of -15 dB is achieved. An operational bandwidth of the full transmission system of at least 10 nm is demonstrated. Both mode MUX and DEMUX are fully reconfigurable and allow a dynamic switch of channel routing in the transmission system.

Reconfigurable photonic integrated mode (de)multiplexer for SDM fiber transmission

Separating optical waveguides are expected to become important in integrated optics. They occur whenever a branching waveguide is used (Fig. 1a) or whenever two parallel waveguides in close proximity are separated (Fig. 1b). These situations will arise in virtually all applications of electrooptic switches and waveguide couplers that depend on evanescent coupling. Using quasi-normal modes and a step transition model we have studied theoretically the mode conversion behavior of separating planar dielectric waveguides as a function of taper slope and mode synchronism, which is adjusted by branch asymmetry. When the taper slope is large in a near symmetric structure, considerable mode conversion will occur and the structure will act as a power divider (Fig. 2b). Incident power concentrated in the upper and lower parts of the structure will end up in the upper and lower arms of the branch, respectively. This behavior is usually required for conventional evanescent couplers. However, in a more asymmetric structure with smaller taper slope, mode conversion is negligible and the structure will act as a mode splitter (Fig. 2a). Mode power is then transferred to one arm of the branch or the other. The transition boundary between a power divider and mode splitter (Fig. 3) is conveniently described approximately by: equation Here Δβ is the difference in mode propagation constant for large waveguide separation, θ is the taper slope, and γ is the decay constant of the field in the separating region. This result will allow quantitative design of mode splitters or power dividers, as desired, and should aid in the design of separating waveguides with minimum radiation losses.

Mode conversion in planar dielectric separating waveguides

Use of CCD and CID technology at or near the focal plane for multiplexing and signal processing will make practical IR focal planes with thousands of detectors. Two approaches to series-parallel scan appear interesting: a sandwich like structure which uses direct injection from the IR detectors into a CCD TDI register and the use of an IR CID for premultiplexing in a series-parallel scan mode.

http://ieeexplore.ieee.org/iel5/9941/31745/01478293.pdf

A.F. Milton

Papers

Mode conversion in planar dielectric separating waveguides

IR Focal plane array imaging devices