Zaven Kalayjian - Academia.edu (original) (raw)

Papers by Zaven Kalayjian

LEOS 2000. 2000 IEEE Annual Meeting Conference Proceedings. 13th Annual Meeting. IEEE Lasers and Electro-Optics Society 2000 Annual Meeting (Cat. No.00CH37080)

... unpolished. The unpolished side gave the sapphire a frosted appearance. ... This effectively ... more ... unpolished. The unpolished side gave the sapphire a frosted appearance. ... This effectively smoothed out the roughness of the unpolished backside and made thesapphire substrate highly transparent to the VCSEL radiation. In ...

The Springer International Series in Engineering and Computer Science

We describe a system that communicates motion information computed in a 2D photosensitive array u... more We describe a system that communicates motion information computed in a 2D photosensitive array using fully arbitered, asynchronous channels. The architecture is neurally inspired, and employs analog winnertakes-all (WTA) circuits, instead of the digital binary-tree arbiters found in other designs. We have fabricated a prototype system that incorporates an array of 9 x 12 pixels in a 2µm, double-polysilicon, double-metal process. Experimental results verify system functionality with a full-handshaking communication cycle of 3µs. We have tested the WTA circuits independently, and have verified their operation down to an 18 ns cycle.

2000 IEEE International Symposium on Circuits and Systems. Emerging Technologies for the 21st Century. Proceedings (IEEE Cat No.00CH36353)

We characterized photodetector mismatch in 2µm and 1.2µm CMOS processes. 32x32 element photodiode... more We characterized photodetector mismatch in 2µm and 1.2µm CMOS processes. 32x32 element photodiode and phototransistor arrays were fabricated in each process. Light response measurements were made using a DC light source and neutral density "lters. Dark currents were also measured and characterized. Our measurements reveal less than 2% mismatch for photodiodes over 4 orders of magnitude of intensity, and less than 5% mismatch for phototransistors. The oxide pro"le above the photodetector array is shown to be responsible for edge-effects.

IJCNN'99. International Joint Conference on Neural Networks. Proceedings (Cat. No.99CH36339)

Polarization vision is prevalent among insects, and offers visual capabilities that contribute to... more Polarization vision is prevalent among insects, and offers visual capabilities that contribute to object discrimination and homing tasks. We present a CMOS imager that is capable of extracting polarization contrast in a scene. A similar visual modality has been seen in Octopus. The polarimetric vector is a more general descriptor of light than intensity information alone, and it contains physical information about the imaged objects in a scene that traditional intensity based sensors ignore. Polarimeters-devices that measure polarization-are used to extract physical features from an image such as specularities, occluding contours, and material properties. Polarization information is used to perform difficult tasks such as image segmentation and surface reconstruction, object orientation, material classification, atmospheric and solar analysis. The polarization contrast retina is a CMOS sensor/imager that uses a birefringent crystal micropolarizer mounted on the focal plane to sense two orthogonal directions of linear polarization. The CMOS imager uses analog translinear circuitry to compute, in real-time on the focal-plane, polarization contrast: a measure of the orientation and degree of linear polarization in an imaged scene

IEEE International Symposium on Circuits and Systems, 2000

We describe the implementation of one channel of an optoelectronic orientation enhancement algori... more We describe the implementation of one channel of an optoelectronic orientation enhancement algorithm based on a neurally inspired algorithm. An 8×8 VCSEL (Vertical Cavity Surface Emitting Laser) array, hybridized to CMOS driver circuits, transmits a contrast-enhanced image that would be computed in the early stages of visual processing. A diffractive optical element (DOE) generates a projective field which reinforces pixels

IEEE transactions on biomedical circuits and systems, Jan 11, 2015

We present a high-voltage CMOS neural-interface chip for a multichannel vestibular prosthesis (MV... more We present a high-voltage CMOS neural-interface chip for a multichannel vestibular prosthesis (MVP) that measures head motion and modulates vestibular nerve activity to restore vision- and posture-stabilizing reflexes. This application specific integrated circuit neural interface (ASIC-NI) chip was designed to work with a commercially available microcontroller, which controls the ASIC-NI via a fast parallel interface to deliver biphasic stimulation pulses with 9-bit programmable current amplitude via 16 stimulation channels. The chip was fabricated in the ONSemi C5 0.5 micron, high-voltage CMOS process and can accommodate compliance voltages up to 12 V, stimulating vestibular nerve branches using biphasic current pulses up to 1.45±0.06 mA with durations as short as 10 μs/phase. The ASIC-NI includes a dedicated digital-to-analog converter for each channel, enabling it to perform complex multipolar stimulation. The ASIC-NI replaces discrete components that cover nearly half of the 2nd...

Proceedings of 2003 5th International Conference on Transparent Optical Networks, 2003.

We propose a novel optical ring network configuration using cascaded optical modulators for data ... more We propose a novel optical ring network configuration using cascaded optical modulators for data communication, and consider different MAC protocol possibilities for this topology. For a unidirectional optical ring, a modified token ring (MTR) MAC protocol is proposed and comparative throughput analysis is performed. For a two-fiber/wavelength topology, the protection/restoration and Ethernet protocol usage possibilities are discussed.

2011 IEEE International Symposium of Circuits and Systems (ISCAS), 2011

In this work, we utilize a CMOS active pixel sensor in a fluorescence imaging setup. The ability ... more In this work, we utilize a CMOS active pixel sensor in a fluorescence imaging setup. The ability to sense small light intensity changes on top of a large baseline with spatial resolution at the subcellular scale is required in fluorescence imaging. The CMOS imager presented in (1) is perfect for this application with the ability to resolve fine features coupled

Optoelectronic Interconnects VIII, 2001

A high-bandwidth, free-space integrated optoelectronic interconnect system was built for high-den... more A high-bandwidth, free-space integrated optoelectronic interconnect system was built for high-density, parallel data transmission and processing. Substrate-emitting 980 nm vertical-cavity surface-emitting laser (VCSEL) arrays and photodetector arrays, both driven by complimentary metal- oxide-semiconductor (CMOS) circuitry, were employed as a transmitter and receiver. We designed, fabricated, hybridized, and packaged the VCSEL transmitter and photoreceiver arrays. Data rates above 1 Gbs for each channel on the VCSEL/CMOS emitter and 500 MHz for each channel on photoreceiver were measured, respectively. We integrated the optical interconnects using free-space optical alignment and demonstrated serial and parallel transmissions of digital data and video images.

Optics Communications, 2002

The stationary form of a femtosecond pulse in an anomalously dispersive medium with third-order n... more The stationary form of a femtosecond pulse in an anomalously dispersive medium with third-order nonlinearity in the presence of quasi-continuous radiation is obtained by solving the wave equation. It is found that under these conditions the soliton reconstruction period ...

Microwave and Optical Technology Letters, 2002

A mathematical description of the spectral and temporal changes in a probe pulse occurring as a r... more A mathematical description of the spectral and temporal changes in a probe pulse occurring as a result of cross-phase modulation interaction between the probe pulse and a soliton with a nonoverlapping spectrum and different delay copropagating in a single-mode fiber was obtained. We show that information on the time delay between a soliton and a probe pulse can be extracted by analyzing the probe pulse spectral density distribution. This information can be used to measure timing jitter in a soliton communication systems.

Microwave and Optical Technology Letters, 2003

The analytical solution of a wave equation that describes the propagation of a femtosecond laser ... more The analytical solution of a wave equation that describes the propagation of a femtosecond laser pulse in a dispersion-free finitelength spatially chirped medium with 1D periodic inhomogeneity is presented. Such media are important to modern optics and are found in holograms, lasers, Bragg reflectors, compressors, and other applications. FDTD numerical modeling confirms the validity of our analytic results.

ISA Transactions, 1999

The polarimetric vector is a more general descriptor of light than intensity information alone, a... more The polarimetric vector is a more general descriptor of light than intensity information alone, and it contains physical information about the imaged objects in a scene that traditional intensity based sensors ignore. Polarimeters Ð devices that measure polarization Ð are used to extract physical features from an image such as specularities, occluding contours, and material properties. Scientists use polarization information to perform dicult tasks such as image segmentation and surface reconstruction, object orientation, material classi®cation, atmospheric and solar analysis. We will present an integrated CMOS sensor/imager that uses a unique polymer-based polarizing ®lter to sense two orthogonal directions of linear polarization. The CMOS imager uses analog translinear circuitry to compute, in real-time on the focal-plane, polarization contrast: a measure of the orientation and degree of linear polarization in an imaged scene. We will present the microfabrication technique that enables us to apply CMOS fabrication technology to bulk manufactured poly(vinyl alcohol) linearly polarizing ®lms. This technique allows us to de®ne lithographically micronscale linearly polarizing regions in polymer-based polarizing ®lters in order to make a high resolution polarization contrast imager.

IEEE Sensors Journal, 2002

Polarization is a general descriptor of light and contains information about reflecting objects t... more Polarization is a general descriptor of light and contains information about reflecting objects that traditional intensity-based sensors ignore. Difficult computer vision tasks such as image segmentation and object orientation are made tractable with polarization vision techniques. Specularities, occluding contours, and material properties can be readily extracted if the Stokes polarization parameters are available. Astrophysicists employ polarization information to measure the spatial distribution of magnetic fields on the surface of the sun. In the medical field, analysis of the polarization allows the diagnose of disease in the eyes. The retinae of most insect and certain vertebrate species are sensitive to polarization in their environment, but humans are blind to this property of light. Biologists use polarimeters to investigate behaviors of animals-vis-à-vis polarization-in their natural habitats. In this paper, we first present the basics of polarization sensing and then discuss integrated polarization imaging sensors developed in our laboratory.

IEEE Journal of Solid-State Circuits, 2001

An 80 78 pixels vision chip for focal-plane image processing is presented. The chip employs a Mul... more An 80 78 pixels vision chip for focal-plane image processing is presented. The chip employs a Multiple-Instruction-Multiple-Data (MIMD) architecture to provide five spatially processed images in parallel. The size, configuration, and coefficients of the spatial kernels are programmable. The chip's architecture allows the photoreceptor cells to be small and packed densely by performing all computations on the read-out, away from the array. The processing core uses digitally programmed current-mode analog computation. Operating at 9.6K frames/s in 800-lux ambient light, the chip consumes 4 mW from a 2.5-V power supply. Performing 11 11 spatial convolutions, an equivalent computation (5.5 bit scale-accumulate) rate of 12.4 GOPS/mW is achieved using 22 mm 2 in a 1.2-m CMOS process. The application of the chip to line-segment orientation detection is also presented. Index Terms-Edge detection chip, focal-plane processing, image processor chip, orientation detection chip, programmable analog computation, vision chip.

IEEE Journal of Selected Topics in Quantum Electronics, 2003

Multichannel optical interconnects were developed using vertical-cavity surface-emitting laser (V... more Multichannel optical interconnects were developed using vertical-cavity surface-emitting laser (VCSEL) arrays and metal-semiconductor-metal photodetector (PD) arrays and driven by complementary metal-oxide-semiconductor circuits that were fabricated using ultrathin silicon-on-sapphire (SOS) technology. Low-threshold oxide-confined top-emitting VCSEL 8 8 arrays were designed and fabricated with off-site contact bonding pads. The arrays were flip-chip bonded to driver arrays on sapphire substrates and mounted on high-speed printed-circuit boards as optical transmitter arrays. The laser output was transmitted through the transparent sapphire substrate and coupled to MSM PD arrays and the SOS receiver. This optical interconnect system was demonstrated to operate at a data rate of 1.0 Gb/s per channel with a power consumption of 28 mW for each channel including transmitter and receiver.

IEEE Circuits and Systems Magazine, 2001

Page 1. 22 Silicon on Sapphire CMOS for Optoelectronic Microsystems Silicon on Sapphire CMOS for ... more Page 1. 22 Silicon on Sapphire CMOS for Optoelectronic Microsystems Silicon on Sapphire CMOS for Optoelectronic Microsystems by AG Andreou (andreou@jhu.edu), ZK Kalayjian, A. Apsel, PO Pouliquen, RA Athale, G. Simonis, and R. Reedy ...

Electronics Letters, 1997

The authors propose the design of a 1D polarisation contrast retina. The retina uses two parallel... more The authors propose the design of a 1D polarisation contrast retina. The retina uses two parallel, linear arrays of 29 photodiodes used as sensing elements. A polarising material is placed on the focal plane so that each array of photodiodes receives linearly polarised light whose e-vector components are orthogonal. On-chip analogue subthreshold MOS circuitry computes the polarisation contrast.

Applied Physics Letters, 1997

We report visible (380–650 nm) electroluminescence from reverse-biased silicon p-n junctions and ... more We report visible (380–650 nm) electroluminescence from reverse-biased silicon p-n junctions and from n- and p-type field-effect transistors designed for a standard chip-fabrication process. We measured the spectra of over 40 junctions and devices and found that they differed from previously reported silicon electroluminescence spectra. We use a hot carrier recombination model and account for Fabry-Perot effects to explain the