2. Handling Precautions and Reliability

2-1. (3) Electrical Stress

1. Overcurrent and surge current
   The laser diode lifetime becomes shorter as the operating optical power output increases. The laser diode lifetime cannot be guaranteed when used in excess of the recommended conditions, so be sure to use within the recommended condition ranges. In addition, note that when optical power output in excess of the absolute maximum rating is generated even for an extremely short time, the laser diode may be damaged with the result that the lifetime is shortened or oscillation stops instantly. Damage caused by optical power output in excess of the absolute maximum rating is the most common of all damage caused by electrical stress, and this mechanism is "structural breakdown of parts of the emission edge that reach excessively high temperatures due to excessive light emission".
   
   <Main causes of overcurrent and surge current>
   1. Power supply factors (excessive overshoot in power-on current, etc.)
   2. Adjustment error factors (optical power output adjustment knob overrun, etc.)
   3. Electrical leakage or inter-line potential difference factors (current flowing simply when a connection is made, etc.)
   4. Static electricity factors (electrical charges accumulated by laser diodes or surrounding items, etc.)
   5. Faulty connection factors (chattering, etc.)
   6. Operation error factors (circuit disconnection in the powered state, etc.)
   7. Operating condition factors (use in excess of the recommended conditions, etc.)
2. Static electricity
   Care should be taken for static electricity, as this is cause of surge current flowing to the laser diode.
   The conditions under which static electricity flows to a laser diode are no different from those for overcurrent, and the damage mechanism is also the same. Procedures for dealing with static electricity vary depending on the conditions, but in consideration of cost effectiveness, the fundamental approaches are as follows.
   1. Do not allow charges accumulated as static electricity to flow to the laser diode leads.
   2. When this cannot be avoided, take steps to limit the amount of current that flows.
   3. Always maintain the laser diode anode and cathode at the same potential when the power is off.
   4. Take steps to restrict the generation of or eliminate static electricity.
   * Special care should be taken to prevent the package of resinous package parts from being charged with static electricity.
   
   For basic measures against static electricity, see the " Quality and Reliability Handbook" published by Sony.
   http://www.sony.net/Products/SC-HP/tec/catalog/qr.html