Application Cases

Experiment Title: Testing of Basic Parameters of Optical Waveguide Ring Resonators

Testing Purpose:To test the Q factor, Full Width at Half Maximum (FWHM), and Free Spectral Range (FSR) of an optical waveguide ring resonator. Since the same optical waveguide ring resonator is used, testing the basic parameters of either the reflection spectrum from the Through port or the transmission spectrum from the Drop port is sufficient. Here, the reflection spectrum from the Through port of the optical waveguide ring resonator is chosen for testing.

Testing Equipment:Voltage Amplifier, Laser, Signal Generator, Optical Waveguide Ring Resonator, Photodetector, Oscilloscope, etc.

Experiment Process:

Figure 1: Schematic Diagram of the Testing System for Basic Parameters of Optical Waveguide Ring Resonators

A testing system platform for the parameters of the optical waveguide ring resonator is set up as shown in Figure 1. The laser used is an ultra-narrow linewidth laser with an output wavelength of 1550nm and a linewidth of 1kHz, featuring wavelength tunability with a tuning range of 22pm. The laser provides an external voltage modulation port. Under the scanning action of an external signal source, the output wavelength of the laser changes periodically. The PZT of the laser has a response bandwidth of 20kHz, with an input voltage range of 0-200V. Therefore, the signal generator produces a signal source for scanning the laser's PZT. After adjusting the gain and offset of the signal source generated by the signal generator on the voltage amplifier, it is input into the external voltage modulation port of the laser. The wavelength-tunable light signal emitted by the laser enters the optical waveguide ring resonator, where wavelengths that meet the resonance conditions resonate within the resonator. The resonant light is then converted from an optical signal to an electrical signal by a photodetector, and the resulting resonance spectrum is observed on an oscilloscope. Figure 2 shows the test spectrum from the Through port of the optical waveguide ring resonator.

Figure 2: Test Spectrum of the Optical Waveguide Ring Resonator

Experimental Results:

In Figure 2, the light blue curve represents the sine wave scanning curve, and the dark blue curve represents the resonance spectrum (reflection spectrum) under sine wave scanning. When testing and calculating the FWHM and FSR of the optical waveguide ring resonator's spectrum, the cursor tool of the oscilloscope is used for measurement.

Voltage Amplifier Recommendation: ATA-2042

Figure: Specifications of the ATA-2042 High Voltage Amplifier

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