1 • forward characteristic
In electronic circuits, the anode of the diode at the hot end, negative at the low end, the diode will conduct this connection, known as the forward bias. Have to say, when the diode forward voltage is very small, diode still cannot pass, forward current flows through the diode is very weak. Only when the voltage reaches a certain value (this value is called "threshold voltage" GE tube is approximately 0.2V, Silicon is about 0.6V), the diode conduction. Breakover diode voltages remain essentially unchanged (GE tube is approximately 0.3V, silicon tube is approximately 0.7V), referred to as diode "pressure drop".
2 • reverse characteristic
In electronic circuits, the anode of the diode at the cool end, negative at the hot end, little current in the diode, and diode in a State as at this time, this form of connection, known as reverse bias. When the diode is reverse biased, there will still be a weak reverse current flows through the diode, known as leakage current. When the diode reverse voltage is increased to a certain value, reverse current increases considerably, the diode will lose single-direction conductivity, this State is called the breakdown of the diode. Injected current must be greater than the critical current density of the laser diode, laser to reverse conditions are met and issued. Critical current density and the surface temperature, and indirectly benefit. High temperature operations, critical current increase, profitability and decrease or even damage components.