LED vs LD efficiency

What is the input/output efficiency of LDs versus LEDs? That is, if you put the same amount of power in to a red 650nm LED and 650nm LD, without any optics beyond the diode window/LED dome, which one will register higher on an LPM, and by how much?

Laser diodes are often a bit more efficient. You can expect conversion from electrical power to optical output to be in the order of 20-25% for a good laser diode. Most high power LED's don't go much beyond 10% as is, but they do provide a wider range of colors.

If you want to have just 660 nm, a red LD is more efficient than a red LED... but the red led will probably put out in the 650-620 range, making it appear more bright to the eye.

OK, cool. I was just thinking about how super low power/long runtime is a current fad over at CPF.

The new blue and violet diodes are inefficient compared to the IR and red LDs, since that tech has been around for many more years.

A typical 808nm pump will produce 2W light out with ~4W in, versus 1W light out with ~4W in for the "1W" 445nm diodes we are using.

I don't play much with LEDs, though, so I don't know any specific figures for their power to light efficiency...

RA_pierce said:

The new blue and violet diodes are inefficient compared to the IR and red LDs, since that tech has been around for many more years.

A typical 808nm pump will produce 2W light out with ~4W in, versus 1W light out with ~4W in for the "1W" 445nm diodes we are using.

Click to expand...

Thats true, but 1 watt of optical output for 4 watts of electrical power is still amazingly good compared to most other light sources. 25% efficiency gives fluorescent tubes a run for their money, though sodium lights still remain unsurpassed.

Yup^, except for a select few (experimental?) low power LEDs. and just to throw a number on it:
According to Phillips and the CIE charts on luminous efficacy,

32000lm/180W * W/520lm = 61Watts light output for 180W

Low pressure sodium lamps can have 34% efficiency.