Flip-chip bonded hybrid CMOS/SEED optoelectronic smart pixels

Hybrid integration of GaAs/AlGaAs multiple quantum well self electro-optic effect device (SEED) arrays are demonstrated flip-chip bonded directly onto 1 mu m silicon CMOS circuits. The GaAs/AlGaAs MQW devices are designed for 850 nm operation. Some devices are used as input light detectors and others serve as output light modulators. The measurement results under applied biases show good optoelectronic characteristics of elements in SEED arrays. Nearly the same reflection spectrum is obtained for the different devices at an array and the contrast ratio is more than 1.2:1 after flip-chip bonding and packaging. The transimpedance receiver-transmitter circuit can be operated at a frequency of 300 MHz.

VCSEL based optoelectronic multiple chip modules

We report on optoelectronic multiple chip modules, consisting of vertical cavity surface emitting laser(VCSEL), photodetector and 1.2 mum CMOS electronic circuit, The hybrid integrated components operate at a date rate of 155Mb/s, which could be used in optical interconnects for multiple computers.

Multiple quantum well self electro-optic effect devices for optoelectronic smart pixels

The investigations on GaAs/AlGaAs multiple quantum well self electro-optic effect device (SEED) arrays for optoelectronic smart pixels are reported. The hybrid integration of GaAs/AlGaAs multiple quantum well devices flip-chip bonding directly over 1 mu m silicon CMOS circuits are demonstrated. The GaAs/AlGaAs multiple quantum well devices are designed for 850nm operation. The measurement results under applied biases show the good optoelectronic characteristics of elements in SEED arrays. The 4x4 optoelectronic crossbar structure consisting of hybrid CMOS-SEED smart pixels have been designed, which could be potentially used in optical interconnects for multiple processors.

Flip-chip bonded hybrid CMOS/SEED optoelectronic smart pixels

Hybrid integration of GaAs/AlGaAs multiple quantum well self electro-optic effect device (SEED) arrays are demonstrated flip-chip bonded directly onto 1 mu m silicon CMOS circuits. The GaAs/AlGaAs MQW devices are designed for 850 nm operation. Some devices are used as input light detectors and others serve as output light modulators. The measurement results under applied biases show good optoelectronic characteristics of elements in SEED arrays. Nearly the same reflection spectrum is obtained for the different devices at an array and the contrast ratio is more than 1.2:1 after flip-chip bonding and packaging. The transimpedance receiver-transmitter circuit can be operated at a frequency of 300 MHz.

Optoelectronic Smart Pixels Comprising Flip-Chip-Bonded GaAs/AlGaAs MQW Detectors and Modulators on Silicon CMOS Circuit

于2010-11-23批量导入

Strained MQW electro-absorption modulators with high extinction ratio and low capacitance

We fabricate an electro-absorption modulator for optical network system using a new strategy, the improved modulation properties of the strained InGaAs/InAlAs MQW show it's polarization independent, high extinction ratio (> 40dB) and low capacitance (C <0.6pF) which can achieve an ultra-high frequency(> 10GHz). The device is be used in 10Gbps optical time division multiplex (OTDM) system as a signal generator.

Tandem electroabsorption modulators integrated with DFB laser by ultra-low-pressure selective-area-growth MOCVD for 10 GHz optical short pulse generation

　

Effect of Si-Ge interdiffusion on the waveguide properties of SiGe-Si MQW photodetector

Because of Si-Ge interdiffusion in the Si-SiGe interface during the growth process, the square-wave refractive index distribution of a SiGe-Si multiple-quantum-web (MQW) will become smooth. In order to simulate the actual refractive index profile, a staircase approximation is applied. Based on this approach, the dispersion equation of the MQW waveguide is obtained by using a transfer matrix method, The effects of index changes caused by the interdiffusion on the optical field and the characteristics of the photodetector are evaluated by solving the dispersion equation, It is shown that the Si-Ge interdiffusion can result in a reduction of the effective absorption coefficient and the quantum efficiency.

Ghrelin gene-related peptides : multifunctional endocrine/autocrine modulators in health and disease

Ghrelin is a multi-functional peptide hormone which affects various processes including growth hormone and insulin release, appetite regulation, gut motility, metabolism and cancer cell proliferation. Ghrelin is produced in the stomach and in other normal and pathological cell types. It may act as an endocrine or autocrine/paracrine factor. The ghrelin gene encodes a precursor protein, preproghrelin, from which ghrelin and other potentially active peptides are derived by alternative mRNA splicing and/or proteolytic processing. The metabolic role of the peptide obestatin, derived from the preproghrelin C-terminal region, is controversial. However, it has direct effects on cancer cell proliferation. The regulation of ghrelin expression and the mechanisms through which the peptide products arise are unclear. We have recently re-examined the organisation of the ghrelin gene and identified several novel exons and transcripts. One transcript, which lacks the ghrelin-coding region of preproghrelin, contains the coding sequence of obestatin. Furthermore, we have identified an overlapping gene on the antisense strand of ghrelin, GHRLOS, which generates transcripts that may function as non-coding regulatory RNAs or code for novel, short bioactive peptides. The identification of these novel ghrelin-gene related transcripts and peptides raises critical questions regarding their physiological function and their role in obesity, diabetes and cancer.

Intensity dependent residual amplitude modulation in electro-optic phase modulators

Residual amplitude modulation (RAM) mechanisms in electro-optic phase modulators are detrimental in applications that require high purity phase modulation of the incident laser beam. While the origins of RAMare not fully understood, measurements have revealed that it depends on the beam properties of the laser as well as the properties of the medium. Here we present experimental and theoretical results that demonstrate, for the first time, the dependence of RAM production in electro-optic phase modulators on beam intensity. The results show an order of magnitude increase in the level of RAM, around 10 dB, with a fifteenfold enhancement in the input intensity from 12 to 190 mW/mm 2. We show that this intensity dependent RAM is photorefractive in origin. © 2012 Optical Society of America.

Polarization dependent photorefractive amplitude modulation production in MgO:LiNbO 3 phase modulators

We present experimental and theoretical results of the intensity dependence of residual amplitude modulation (RAM) production in electro-optic phase modulators. By utilizing the anisotropy of the medium, we show that RAM has a photorefractive origin.

Reducing residual amplitude modulation in electro-optic phase modulators by erasing photorefractive scatter

Residual amplitude modulation (RAM) is an unwanted noise source in electro-optic phase modulators. The analysis presented shows that while the magnitude of the RAM produced by a MgO:LiNbO3 modulator increases with intensity, its associated phase becomes less well defined. This combination results in temporal fluctuations in RAM that increase with intensity. This behaviour is explained by the presented phenomenological model based on gradually evolving photorefractive scattering centres randomly distributed throughout the optically thick medium. This understanding is exploited to show that RAM can be reduced to below the 10-5 level by introducing an intense optical beam to erase the photorefractive scatter.

Investigation of the intensity dependence of amplitude noise in electro-optic phase modulators

This thesis studied the source of instability in optical phase modulators used in high accuracy laser measurement systems. The nonlinear origin of the amplitude noise helped further reducing this instability in applications that rely on phase modulators to function. This outcome will have positive impacts on the development of new methods in the amplitude noise suppression.

Dependence of residual amplitude noise in electro-optic phase modulators on the intensity distribution of the incident field

Our results demonstrate that photorefractive residual amplitude modulation (RAM) noise in electro-optic modulators (EOMs) can be reduced by modifying the incident beam intensity distribution. Here we report an order of magnitude reduction in RAM when beams with uniform intensity (flat-top) profiles, generated with an LCOS-SLM, are used instead of the usual fundamental Gaussian mode (TEM00). RAM arises from the photorefractive amplified scatter noise off the defects and impurities within the crystal. A reduction in RAM is observed with increasing intensity uniformity (flatness), which is attributed to a reduction in space charge field on the beam axis. The level of RAM reduction that can be achieved is physically limited by clipping at EOM apertures, with the observed results agreeing well with a simple model. These results are particularly important in applications where the reduction of residual amplitude modulation to 10^-6 is essential.