Optical Transceiver

Testing Using the

Viavi Solutions™

Multiple Application

Platform (MAP-200)

Application Note

An optical transceiver is a single, packaged device that works as a transmitter and receiver. It

is an important part of optical network equipment that converts electrical signals to optical

signals and vice versa. Optical transceivers are widely deployed today in synchronous optical

Several standards bodies govern optical transceiver specifications.

The Telecommunication Standardization Sector of the International

Telecommunication Union (ITU-T) and Telcordia are the two major

standards organizations for telecom, while the Institute of Electrical

and Electronic Engineers (IEEE) and the American National Standard

Institute (ANSI) are the major standards organizations for datacom.

In addition, several transceiver manufacturers have established a

multi-source agreement (MSA) to ensure interoperability. The scope

of the MSA includes mechanical, electrical and optical specifications.

In today’s market, transceivers with bit rates below 10 Gb/s come in

An optical transceiver data sheet usually includes mechanical,

electrical, and optical specifications. To guarantee compliance to

specifications and industry standards, testing of the electrical and

optical parameters is an essential step in the manufacturing process.

Optical parameters can be further divided into two categories:

transmitter and receiver. Table 1 shows some of the main parameters

specified by transceiver manufacturers.

 Optical Transceiver Testing Using the Viavi Solutions Multiple Application Platform (MAP-)

Transmitter Optical Parameters Receiver Optical Parameters

Average Optical Power Receiver Sensitivity

Extinction Ratio Stressed Receiver Sensitivity

Table 1. Main parameters specified by transceiver manufacturers

The following section discusses testing of transmitter average optical

power and receiver sensitivity. These two parameters are used in link

power budget analysis at the system level to determine the power

margin of an optical link. This margin is allocated for connector, splice,

fiber losses, and system margin.

Transmitter Average Optical Power

Measurement

The transmitter port of an optical transceiver consists of a light

source and associated electronic circuitry. Semiconductor-based light

which is a process of applying varied current to the laser to change

the output power level. As illustrated in Figure 1, a finite power level

represents logic zero rather than a true complete absence of power.

Data transmission up to 10 Gb/s uses the non-return-to-zero (NRZ)

modulation scheme. In the NRZ data stream, there is equal probability

of logic 1 and logic 0 over a long period of time. Transmitter average

optical power, Pavg is a measure of the average energy of logic 1, P1,

and logic 0, P0, coupled into the fiber over a period of time.

measurement unit is usually expressed in dBm, a logarithmic ratio of

power level to 1mW.

Transmitter average optical power measurement is a typical production

test performed to ensure that the transmitter meets the specified

performance, as Figure 2 shows. This measurement is usually taken

using a suitable length of a pseudo-random bit sequence (PRBS) data