Jean-Luc Polleux

Optimization of InP-InGaAs HPT gain: design of an opto-microwave monolithic amplifier

We have designed an opto-microwave monolithic amplifier with emphasis on the definition of the opto-microwave power gain. First, we present physical simulations of an InP-InGaAs heterostructure phototransistor (HPT), which enable the structural analysis of the composition and behavior of the phototransistor. From these simulations and from both electrical and optical measurements, we next established a large-signal model, which adds photoelectric effect to an HBT model. Small-signal opto-microwave S-parameters of the HPT are first defined and then related to the small-signal opto-microwave power gain of the phototransistor. Relations are given to enable optimum loads on the base and collector ports to be found so that the opto-microwave gain can be optimized. An opto-microwave amplifier is then designed, realized, and measured with a setup based on the beating of two lasers.

A strained SiGe layer heterojunction bipolar phototransistor for short-range opto-microwave applications

A strained-SiGe heterojunction bipolar phototransistor is presented for the first time. Theoretical demonstration of the device is recalled. Practical measurements at 940 nm are presented. A dc phototransistor mode responsivity of 1.49 A/W is achieved. Tools are proposed for the opto-microwave behavior analyses of photodetectors. A frequency behavior reaching 32 GHz with a -70 dBm output level and a 200 /spl mu/W input optical power is demonstrated.

Opto-microwave experimental mapping of SiGe/Si phototransistors at 850 nm

This paper presents measurement results providing the mapping of the opto-microwave transfer function performed on an SiGe microwave heterojunction phototransistor (HPT). This measurements will be used to extract a guideline for designing phototransistors. A mapping of the HPTs gain in low frequency helps to estimate the shape of the optical beam used for the measurement. The study also focuses on the cutoff frequency mapping of the device in phototransistor mode. Finally, these results are used to determine the general optimization rules in the SiGe HPTs design.

Light Emitting Devices in Si CMOS and RF Bipolar Integrated Circuits

ABSTRACT In this article, we discuss the emission of visible light (400–900 nm) by a monolithically integrated silicon p-n junction under reverse bias. Silicon light emitting devices (Si-LEDs) could be designed and realized utilizing the standard complementary metal oxide semiconductor (CMOS) technology. Increased electroluminescence from the three-terminal MOS-like structure is observed, with the approach of carrier energy and momentum engineering design. Because Si-LEDs, waveguides, and photodetectors (Si) can be integrated on a single chip, a small microphotonic system could be realized in the CMOS integrated circuitry standard platform. The results can be substantially utilized for realizing a complete on-chip optical link.

Light emission in silicon: from device physics to applications

Silicon Photonics is an emerging field of research and technology, where nano-silicon can play a fundamental role. Visible light emitted from reverse-biased p-n junctions at highly localized regions, where avalanche breakdown occurs, can be used to realize a visible electro-optical sources in silicon by means of light-emitting diodes (Si-LEDs) is reviewed by characterizing the spectral distribution. Regarding applications, a monolithic optoelectronic integrated circuit (OEIC) for on-chip optical interconnection based on standard CMOS technology is discussed. Although there are some of the present challenges with regard to the realization of suitable electro-optical elements for diverse integrated circuit applications, the type of silicon light source can be further developed into be a Si-based optical short-distance on-chip optical interconnect applications.

Co-simulation-based modeling and performance analysis of hybrid fiber-wireless links

SUMMARY We present a new approach for the performance analysis of hybrid fiber/wireless communication systems. This approach is based on a co-simulation using two types of dedicated software: the first is used for RF/wireless systems whereas the second is devoted to optical communication systems. The proposed method enables simultaneous simulation of all elements of the radio-over-fiber link with accurate modeling. A low-cost wireless local area network over a fiber distribution system is implemented in order to validate the results experimentally. Simulation results are in good agreement with experimental measurements in terms of EVM evolution for different link element configurations. Copyright

Design and implementation of SiGe HPTs using an 80GHz SiGe bipolar process technology

We present the design and characterization of SiGe Heterojunction Phototransistors using an 80GHz commercial SiGe Bipolar process. It is shown that 50µm HPTs are exhibits highest gain.bandwidth product of 0.8GHz.A/W compared to the 10µm HPTs

Silicon Avalanche Based Light Emitting Diodes and Their Potential Integration into CMOS and RF Integrated Circuit Technology

As a rapid growing field in worldwide science and technology, silicon nano-photonics has become one of the most promising photonics integration platforms in the last decade. This is mainly due to the combination of a very high index contrast and the availability of silicon complementary metal-oxide-semiconductor (CMOS) fabrication technology, which allows the use of electronics fabrication facilities to make photonic circuitry. Unfortunately, the indirect band-gap of silicon leads to low efficiency and slow efficiency that is unexpected. The rate of electron-hole recombination in silicon material is too low to produce emitted photons in forward biased silicon p-n junctions, but light emission observed from reverse-biased silicon p-n junctions under high electric field was already reported in 1955 by Newman [1]. The radiative transition between hot carriers emits photons larger than the energy gap. Hence the luminescence during avalanche breakdown is characterized by a broad emission spectrum. An example of the high-energy edges of avalanche-breakdown luminescence is shown in Fig. 1. The low-energy edge of the emission spectrum, on the other hand, extends to energies lower than the gap energy, due to the tunneling-assisted photon emission [2].

Full area emitter SiGe phototransistor for opto-microwave circuit applications

We present a study of full area emitter phototransistors with different optical window sizes implemented in a SiGe Bipolar technology. Extracted responsivity of 3.5 A/W and an opto-microwave cut-off frequency of 739 MHz were observed.

Modal Noise Mitigation in 850-nm VCSEL-Based Transmission Systems Over Single-Mode Fiber

Various short-range optical connections, transmitting either high-bit-rate digital signals or radio frequency analog signals, can exploit 850-nm vertical-cavity surface-emitting lasers as optical source together with the standard single-mode fiber (SSMF) as optical channel. This solution presents attractive features in terms of reduced cost and energy consumption. However, bandwidth reduction due to intermodal dispersion and undesired fluctuations of the received signal due to modal noise are present in this case. Such effects are studied theoretically and experimentally, and a cost-effective solution is proposed to reduce their impact. Hence, connections with SSMF length up to 300 m with 3-dB bandwidth of 2500 MHz are demonstrated, while the modal noise is reduced to a standard deviation of less than 2 dB.