Light emiting diodes LEDs compared to laser diodes ?

[Externet]

Greetings.

When a LED specifications shows a 30 milliamperes maximum current and is driven to a third as 10 mA or even less,  the life expectancy is considerably extended and its behavior as a panel indicator is still fully useable.

Is a laser diode with a maximum current specified as 30mA also perform as a beam emitter at a third of the current (10ma) or less; or lasing is impaired and there is a minimum current needed ?   What is the term specified for the current that starts to produce lasing ?    If a laser diode is needed in operation 365 days non-stop;  would underpowering it extend its life equally as happens with a LED ?  What type of visible light laser construction could last emitting a beam  for not less than a year ?

[John Cuthber]

Threshold current.
Lifetime sees mainly temperature dependent so a reduced power presumably increases lifetime
https://www.newport.com/medias/sys_master/images/images/hbc/h43/8797050241054/AN33-Estimating-Laser-Diode-Lifetimes-and-Activation-Energy.pdf

[studiot]

8 hours ago, Externet said:

Greetings.

When a LED specifications shows a 30 milliamperes maximum current and is driven to a third as 10 mA or even less,  the life expectancy is considerably extended and its behavior as a panel indicator is still fully useable.

Is a laser diode with a maximum current specified as 30mA also perform as a beam emitter at a third of the current (10ma) or less; or lasing is impaired and there is a minimum current needed ?   What is the term specified for the current that starts to produce lasing ?    If a laser diode is needed in operation 365 days non-stop;  would underpowering it extend its life equally as happens with a LED ?  What type of visible light laser construction could last emitting a beam  for not less than a year ?

 

John is quite correct to highlight threshold current (not maximum current) as the important parameter.  +1

Threshold current is the minimum current at which lazing starts.  Threshold current increases with increasing temperature.

Laser diode characteristics are normally given at a case temperature of 25^oC.

Increasing temperature creates heat which increases case temperature so ther possibility of thermal runaway or at least degrading should be considered.

Considering where you live and your requirements this could be more difficult as running the laser current too low on cold nights will increase the risk of laser dropout.

Since absolute temperature is an absolute maximum you need to run the device between a current suitably above threshold for your minimum temperature but as far below you maximum current as you can, consistent with the requirement that the top level will be determined by your maximum ambient + 5^oC (and you live in a hot area).

 

Without further details of your requirement, but guessing from your other thread that you want the laser to sweep to and fro for a year I really can't be more specific on diodes.

But I would like to note that lasers are inherenttly dangerous things so you need to consider safety in the illuminated area.

Also note that laser diodes require a current controlled drive, not a voltage drive.

[swansont]

9 hours ago, Externet said:

would underpowering it extend its life equally as happens with a LED ? 

In my experience yes.

9 hours ago, Externet said:

What type of visible light laser construction could last emitting a beam  for not less than a year ?

I’ve used commercially-available systems that lasted around 1.5 years or so; generally the failure was degradation of the anti-reflection coating, and the laser wouldn’t stay at the desired frequency, but they would still lase. 

If it’s a homemade system, it’s critical that the electronics prevent the laser from seeing voltage spikes. Those will destroy a laser diode.

[Externet]

Thanks, +3

I will aim then to just above threshold current and care on heat dissipation.

 

Edited December 14, 2023 by Externet

[John Cuthber]

If it's really important then you need thermostatic heating /cooling and a constant current driver.