High-Fidelity Analog Signal Transmission with the EM530 Fiber Coupled Receiver
Realization of high performance photo receivers with high power handling capabilities has long been recognized as a critical and missing element to achieving high-fidelity transmission of analog (RF) signals over fiber optic links. There are a growing number of industrial and military analog optical communication applications that would stand to benefit from improvements made at the receiver-end, including cable-TV distribution, phased-array antennas and antenna remoting, optical signal processing, secure RF-comms over fiber, coherent lightwave communications, and photonic analog-to-digital conversion. To meet the challenges of these demanding applications, optical receivers must be able to operate at high photocurrent levels to reduce the noise figure, while simultaneously supporting high dynamic range detection and highly linear operation.
In recognition of this need and building on the successes of Gooch & Housego’s EM169 family of high reliability 20GHz fiber-coupled detector modules, engineers at the company have developed a new class of fast and linear optical fiber coupled receiver. Compared to other commercially available solutions, the new G&H receivers offer dramatically improved optical power handling and modulation bandwidth capabilities.
Dubbed EM530, this new family of high power detector modules is capable of highly linear operation for incident optical power levels as high as 20dBm (cw) and for RF modulation frequencies in excess of 10GHz (S21). Designed for both digital and analog applications with a 50 Ohm impedance matched RF connection, the EM530 module contains an InGaAs PIN photodiode and requisite proprietary matching electronics. Typical flatness of the RF response is well within +/- 3dB over the operating frequency range, and the electrical return loss is better than -10 dB (S22). The module is intended for use in single-mode RF photonic links that operate over the 1280nm to 1625nm wavelength window. Typical room-temperature responsivity in the C band is 0.6 A/W (1545nm used as a reference wavelength) and the receiver dark current is on the order of several 10’s of nA, with a conservatively estimated maximum of 100nA. Typical reverse bias is 5V (maximum 10V), corresponding to a maximum power dissipation of 30mW. The optical return loss is normally on the order of -35dB, with higher levels achievable upon demand.
The EM530 receiver sports a small size and footprint: notwithstanding the SMA connector and the approximately 2.5cm long strain-relief pigtail boot section, the module occupies a volume of ~1.2 cm3 and a footprint of ~2.3cm2.
The EM530 module can be stored from -55°C to 85°C, and is currently rated for operation from 0°C to 70°C. Its hermetically sealed and epoxy-free design and the use of other package design elements and assembly and integration processes that are identical with the tried-and-tested EM169 photo-receiver, all indicate that EM530 too will rightfully carry the high-reliability moniker upon completion of environmental and reliability qualifications.
Further details and a datasheet can be downloaded here.
Volume shipments of the EM530 module are available with different fiber-type pigtails (SMF, PM fiber, specialty MFD fiber) and with a number of standard connector options.
Please come past our booth, #1923, at Photonics West, to find out more.