Jason P. Sokoloff

A terahertz optical asymmetric demultiplexer (TOAD)

A device capable of demultiplexing Tb/s pulse trains that requires less than 1 pJ of switching energy and can be integrated on a chip is presented. The device consists of an optical nonlinear element asymmetrically placed in a short fiber loop. Its switching time is determined by the off-center position of the nonlinear element within the loop, and therefore it can use the strong, slow optical nonlinearities found in semiconductors, which all other fast demultiplexers seek to avoid. The switchs operation at 50 Gb/s is demonstrated, using 600-fJ control pulses.<<ETX>>

Performance of a 50 Gbit/s optical time domain multiplexed system using a terahertz optical asymmetric demultiplexer

Bit error rate measurements were performed on a 50 Gbit/s optical time domain multiplexed system which utilized the newly developed terahertz optical asymmetric demultiplexer (TOAD) device as the front end of a receiver. Bit error rates of less than 10/sup /spl minus/9/ were measured when 800 fj control pulses were used to gate the demultiplexer. These measurements, which were made on a 50 Gbit/s peak line-rate train, also quantified the tolerance of the TOAD to signal-control pulse jitter.<<ETX>>

ASYMMETRIC OPTICAL LOOP MIRROR : ANALYSIS OF AN ALL-OPTICAL SWITCH

We present an analysis of the optical loop mirror in which a nonlinear optical element is asymmetrically placed in the loop. This analysis provides a general framework for the operation of a recently invented ultrafast all-optical switch known as the terahertz optical asymmetric demultiplexer. We show that a loop with small asymmetry, such as that used in the terahertz optical asymmetric demultiplexer, permits low-power ultrafast all-optical sampling and demultiplexing to be performed with a relatively slow optical nonlinearity. The size of the loop is completely irrelevant to switch operation as long as the required degree of asymmetry is accommodated. This is therefore the first low-power ultrafast all-optical switch that can be integrated on a single substrate.

Polymer waveguide overlays for side-polished fiber devices

Several polymers often used as hosts in guest-host organic thin-film systems were investigated for their suitability as overlays for side-polished fiber (SPF) devices. Good optical quality, ~10-mum-thick films were fabricated by spin coating and applied to SPFs by use of a decal deposition technique to produce passive devices such as channel-dropping (CD) filters, bandpass filters, and polarizers with good throughput and high contrast ratios. The main CD features can be quantitatively explained by a weak coupled-mode model. SPF structures with doped overlays were also examined. These measurements provided a means of determining several SPF device parameters and also allowed estimates of the nonlinearities required to make all-optical and electro-optic devices.

Ultrafast all-optical photonic packet switching

The use of optical processing to perform switch-routing functions in photonic packet-switching networks prevents electronic data-flow bottlenecks and permits real-time routing of packets at very high speed. The architecture of a 2 X 2 photonic packet-switching node with optical packet generation, optical packet synchronization, optically-processed routing control, contention resolution (using deflection routing), and optical packet demultiplexing is presented. Terahertz optical asymmetric demultiplexers (TOADs), which allow ultrafast optical demultiplexing for terabit per second pulses with less than one picojoule switching energy, are utilized in the switch architecture. A two-channel optical demultiplexing experiment using the TOAD is reported, where two 2 ps, 100 Mbit/s pulse trains are extracted successfully from two time-multiplexed channels with a channel spacing of 40 ps.

Photonic packet switching with optically processed control

We report the first demonstration of all-optical address recognition and self-routing of photonic packets for a case where the packet bit period is only 4 ps, corresponding to a 0.25- Tb/s bandwidth optical network. An ultrafast all-optical devices, known as a terahertz optical asymmetric demultiplexer (TOAD), was used to read the address information encoded in a packet header, which in turn was used to route the packet. The bit-error rate at the switch output was measured to be less than 10-9.

Identification of electronic and thermal optical effects in organic waveguides and etalons

We have developed novel multifunctional chromophores as a new class of organic nonlinear optical molecules for photorefractive applications. Photoconductive property and second-order nonlinear optical response were characterized by xerographic discharge and secondharmonic generation measurements, respectively. Two kinds of molecular systems were studied: acceptor-substituted carbazoles and asymmetrically substituted metallophthalocyanines. Carbazoles and metallophthalocyanines are well known molecules which possess photoconductivities: hole-transporting and carrier generation properties. In order to add the second-order nonlinear optical properties at a molecular level, we introduced acceptor groups into these molecules. The asymmetrically substituted metallophthalocyanines and the carbazole oligomers: head-to-tail linear, cyclic and starburst oligomers, were newly designed as shown in Figure 1. The physical properties of carbazole oligomers are different from corresponding point-like molecules and their optoelectronic properties can be controlled by molecular-level-tuning of the size, shape, surface chemistry, and topology. The carbazole starburst oligomer films obtained by spin-coating were poled and exhibited second-order nonlinear optical responses. The second-order nonlinear optical coefficients d,, were determined to be 50 pm/V

DEMONSTRATION OF 250 GB/S ALL-OPTICAL ROUTING CONTROL OF A PHOTONIC CROSSBAR SWITCH

In future ultra-fast packet-switched networks, individual address bits may be spaced only picoseconds apart. Address recognition will require an ultra-fast demultiplexer which examines the packet header without opto-electronic conversion and without reading the data in the packet’s payload. A low-power device capable of all-optical demultiplexing is the recently-developed Terahertz Optical Asymmetric Demultiplexer (TOAD).1–4

Demonstration of an optically transparent ATM packet switch node

We report on the development of a transparent optical node at 1.3 micrometers wavelength for an ATM packet switch operating at 1.24416 Gbit/s header recognition rates. The node takes advantage of the high-speed performance of optoelectronic components to alleviate potential bottlenecks resulting from optical to electrical conversion experience in nontransparent packet switching architectures. The node is intended for use in two-connected, slotted networks, is self-clocking, and has drop/add multiplexing, buffering, and routing capabilities.

Performance of a terahertz optical asymmetric demultiplexer in a 50-Gbit/s optical time division-multiplexed system

We have measured the performance of a new demultiplexing device, known as a Terahertz Optical Asymmetric Demultiplexer, while operating it in an optical time division multiplexed system with an aggregate bandwidth of 50 Gbits/s. These measurements also illustrate the devices adjustable tolerance to jitter.