Automated Validation of Optical Component Spectral Stability

In wavelength division multiplexing (WDM) systems, high-frequency modulated signals with complex formats are densely packed within the WDM channel. These systems require high stability in wavelength (or frequency) and power. Therefore, long-term stability evaluations, such as temperature cycle tests and high load tests, are essential not only for WDM transmission systems but also for the semiconductor lasers (LD) and optical transceivers that comprise these systems.

A primary reason for these tests is to verify the thermal stability and measurement drift of optical components in an environmental chamber.

Data Logging Function

Most Yokogawa Optical Spectrum Analyzer (OSA) models simplify long-term measurements using built-in data logging and programming functions, eliminating the need for an external PC. The data logging function enables continuous optical spectrum measurement, analysis, and data saving under preset conditions.

During analysis, key parameters such as WDM (peak wavelength, peak level, OSNR) and DFB-LD (SMSR) can be evaluated, with each parameter value recording up to 10,000 data points per peak wavelength (channel). These recorded values are displayed along with their maximum and minimum values in a logging table or graph, with the vertical axis representing the amount of change and the horizontal axis representing time. By moving the cursor, users can display the optical spectrum waveform at specific times, allowing for the observation of both analysis values and temporal changes in the optical spectrum.

Program Function

One of the main challenges in performing long-term stability tests is the need for repetitive and precise measurement procedures, which can be time-consuming and prone to human error if done manually. Additionally, setting up complex measurement sequences often requires software engineering, which can require an external PC, specialized skills and additional costs.

Yokogawa's internal OSA macro programming function addresses these challenges by allowing users to create and register a series of measurement procedures in advance, enabling automatic measurement execution. No programming expertise is required. Creating a program is straightforward, as users can simply select commands corresponding to the OSA keys, mimicking actual OSA operation. This intuitive process ensures that even those without programming knowledge can easily set up and execute complex measurement procedures.

For more sophisticated setups, advanced commands for loop control, condition judgment, variables, arithmetic operations, parameter input, and screen output are also available, making the programming function versatile and powerful while still user-friendly.