Receiver design for high-speed ptical-fiber systems

The technology of optical-fiber systems is advancing rapidly. Parallel to the development of long-haul telecommunication systems in the gigabits per second data rates operating in the long-wavelength region is the wide penetration of optical-fiber systems in local area networks, video trunking and distribution, sensors, etc. These diversified applications impose different and often conflicting constraints on the optical receiver. This paper re-examines the optical receiver design in view of these different requirements, namely, high receiver sensitivity, wide dynamic range, transparent to the operating bit rate, unrestricted data format, and fast acquisition time. Design tradeoffs between conflicting receiver requirements are considered in detail. In particular, the sensitivity of high-capacity long-wavelength transmission systems is emphasized. The state-of-the-art performance of photodetectors and low-noise amplifiers is discussed. We show that dark current of avalanche photodiodes (APD's) is the main factor limiting the sensitivity of long-wavelength optical receivers. In addition, as an example, we report on the design and experimental performance of a hybridized low-noise optical receiver amplifier capable of more than 2-Gbits/s operation. The input noise spectral density achieved is 9 pA/ \sqrt{Hz} with a noise corner frequency of 920 MHz, corresponding to an equivalent noise resistance of 120 Ω.

Receiver design for high-speed optical-fiber systems

Study of Indium Tin Oxide (ITO) for Novel Optoelectronic Devices

The velocity in a supersonic jet flow has been measured using CW CARS and agrees to within 4 percent of the calculated value.

CARS measurement of velocity in a supersonic jet

Publisher Summary This chapter focuses on the use of phototransistors for lightwave systems and photonic circuit applications. The basic operating characteristics of a bipolar phototransistor are described and the optical gain and the common-base and common-emitter current gains are determined from the current transport equations. The chapter derives a model for the noise characteristics of the heterojunction phototransistor (HPT) to project the sensitivity of an optical receiver with an HPT in the front end. The chapter concludes with a discussion on bipolar phototransistors and a review of work on novel structures and the integration of HPTs with other electrooptic components. A description of the operating characteristics of phototransistors with field-effect transistor-like structures is presented along with the results that have been obtained so far.

Chapter 5 Phototransistors for Lightwave Communications

An analysis of the sensitivity of InGaAs/InP bipolar heterojunction phototransistors (HJPT's) used in pulse code modulated optical communications systems is presented. The minimum detectable power of an HJPT biased at the optimum level is found to increase linearly with bit rate B while because of the fixed transconductance of the FET amplifier, the minimum detectable power of a p-i-n FET increases as B^{3/2} . It is shown that HJPT's can thus have higher sensitivity than p-i-n FET detectors, particularly at high bit rates, and can have comparable sensitivity to APD-FET detectors.

K. Tabatabaie-Alavi

Papers

Performance comparison of heterojunction phototransistors, p-i-n FET's, and APD-FET's for optical fiber communication systems