ABSTRACT We describe our approach to the monolithic integration of Ge photodetectors in a photonics-enabled CMOS technology.Ge waveguide photodetectors allow fast and efficient conversion of optical signals in the near infrared (1.55um) to theelectrical domain thus enabling the fabrication of compact, high speed (10Gbps) receivers.Keywords: Ge detectors, Si optoelectronics, waveguide detectors, near infrared, optical communications 1. INTRODUCTION Since the early pioneering works of Soref on the electro-optical properties of Si in the near infrared [1], impressiveprogresses have been done in the field of Si photonics with demonstration of all fundamental building blocks to couple,guide, modulate, filter and detect an optical signal. Today, Si-base d discrete optical components, such as variable opticalattenuators, are commercially available and find use in several applications [2]. While these devices have specificpeculiarities that makes them successful over their dielectric, III-V or polymer-based counterparts in a competitivemarket, they do not exploit, yet, the real advantage of the Si platform, i.e. the monolithic integration of several differentfunctions on the same chip. The latter is expected to bring to the optical transceivers world, the same advantage thatpropelled the ubiquitous success of CMOS electronics: the collapse of the cost per function.Crystalline Si is an excellent optical material, with minimal absorption in the near infrared at the common fiber opticscommunication wavelengths. Moreover, its refractive index can be modulated by injection of free carriers (electrons andholes) to create active optical devices such as modulators and switches. When it comes to photodetection, however, theexcellent transmission properties of Si makes it useless and force the use of other materials with high enough absorptioncoefficient in the wavelength region of interest. Germanium has been identified since long time as a possible candidatefor its excellent transport properties and the high absorption efficiency in the infrared up to 1.55um. This paper reportson the approach developed by Luxtera to integrate Ge photodectors in a CMOS process along with other opticalcomponents to fabricate high speed optical transceivers.