A low-noise amplifier includes a first transistor having a gate configured to receive an oscillating input signal and a source coupled to ground. The semiconductor optical modulator includes a waveguide structure that is formed by sequentially growing an n-type InP clad layer, a semiconductor core layer having an electro-optic effect, a p-InAlAs layer, and an n-type InP clad layer. The system provides features to assist prevention of machine jamming by large debris. The copper-based sliding material has good anti-seizure property and superior resistance to fatigue without containing any lead.