Common BJT amplification stages are effective and easy to calculate. To achieve higher voltage gains, the collector resistor can be replaced by current sources, also made by a BJT. Just for fun, I tried a circuit using a FET as current source and an optical feedback loop. The current is regulated by the gate-source voltage, which in turn can be determined by a resistor between the two. Then the problem of thermal stability arises. On temperature variations, the collector voltage changes, which in turn affects the gain of the amplifier and the maximum output voltage swing. What if the resistor is then adjusted in order to stabilize the collector voltage? This can be achieved by using a photoresistor driven by a light source whose intensity is inversely related to the collector voltage. By adjusting the sensibility of the regulation, quite good thermal stability can be achieved, as well as voltage gain above 600.