FAQ1165

Answer

Vertical-cavity surface-emitting lasers (VCSELs) are semiconductor lasers that have emission wavelengths ranging from visible to the near-infrared (NIR). Due to their design, they have inherently low threshold current requirements, high efficiencies, and narrow linewidth.

Differing from other semiconductor lasers, which emit light parallel to the active region of the laser, VCSELs emit perpendicular to the active region. This distinction is recognized in their name, where the “surface-emitting” can be compared to “edge-emitting.”

Due to this surface-emitting characteristic, VCSELs can be arranged into two-dimensional arrays, allowing for multiple VCSELs to form a high power output, nearing kilowatt power with quasi-continuous wave operation. Their low threshold current also lends them to this array structure, as they will have much lower pumping requirements than edge-emitting lasers.

VCSELs are used in a variety of ways, including fiber optic communication, medical applications, laser projectors, pumping solid state lasers, and computer-related applications.

Packaging ranges from TO cans to chip-mounted assemblies. Additional fiber-coupling into single- or multi-mode fibers is available.

Depending on whether the application includes a single VCSEL or an array, the electrical driving requirements differ. Single VCSELs can have maximum forward currents as low as 3 mA (continuous wave), while high-power arrays can handle up to hundreds of amperes.

Wavelength Electronics offers laser drivers that are well-suited for driving VCSELs with low modulation requirements. The table below shows appropriate products, along with their corresponding leakage and maximum operating currents for easy comparison.

DRIVER	LEAKAGE CURRENT (μA)	MAX CURRENT (A)	DATASHEET
FL5001	50 to 150	0.5
LDTC0520	300 to 1000	0.5
LDTC1020	300 to 1000	1.0
LDTC2/22, 3	350	2.2
PLD200	10	0.2
PLD500	10	0.5
PLD1250	10	1.25
PLD5000	10	5.0
PLD6500	10	6.5
PLD10000	10	10.0
PLD12500	10	12.5
PLD5K-CH	10	5.0
PLD10K-CH	10	10.0
PLD12.5K-CH	10	12.5
WLD33433	350	3.0
WLD33ND3	350	3.0

¹Leakage current specified with FL591 circuitry.
²Leakage current specified with only external voltage setpoint. Possibility of more leakage current if the external voltage setpoint is summed with the on-board trimpot.
³Leakage current specified in the 200 mA output range. For more information, see the product datasheet.

If you have questions regarding the suitability of any product for driving a VCSEL, please contact Wavelength Tech Support (techsupport@www.teamwavelength.com) for free and responsive assistance.