Fig 2 The picture of the SPST integrated switch. (a) The area of 50um thickness SPST switch chip is 2.75mm2; (b) The SPST switch chip was packaged in a waveguide for testing the performance of the switch chip.
The SPST switch chip is packaged in the waveguide with port WR4, as shown in Figure 2 (b). In order to introduce terahertz waves into the SPST switch, quartz probes are employed as transition structures to link on both sides of the SPST switch chip. Place the PIN diode in the appropriate location on the quartz circuit that has been manufactured, then secure it with conductive glue. Gold wire connects the quartz probes to the SPST circuit.
Measurement of the SPST switch: A bias voltage is applied to the switch while a vector network analyzer was used to measure the SPST switch’s cavity. To obtain accurate measurement results of the switch chip, the existing results need to be de-embedded, minus the loss of quartz probes and gold wires, as illustrated in Figure 3(a). The insertion loss is < 3.2 dB from 213 GHz to 230 GHz. The isolation is > 29 dB from 220 GHz to 230 GHz. The results from the measured curve follow the same trend as those from the simulation. The applied voltage range of the SPST switch is from 0 to 1.4 V to achieve a good switching effect, which working current is 10 mA.