Impedance of Laser DiodesInductive behaviour


Related Products: LDP-AV, LDP-V, LDP-CL

 

The parasitic stray inductive behaviour is the most important influence on the pulse rise time. The output voltage of the driver must be able to charge the stray inductance, thus resulting in slower current rise times. The following table shows the stray inductance of commonly used laser diode packages.

Package Drawing

Package Style

Package Inductance


1

Source: LASER COMPONENTS GmbH

8-32 coaxial

12 nH*


2

Source: LASER COMPONENTS GmbH

10-32 coaxial

11 nH*


3

Source: LASER COMPONENTS GmbH

TO-5 2-lead

9,6 nH*


4

Source: LASER COMPONENTS GmbH

TO-52

5,6 .. 6,8 nH*


5

Source: LASER COMPONENTS GmbH

CD 9mm

5,2 … 6,8 nH*


6

Butterfly

22 nH**


7

Dip 14 leaded

15,7 nH


8

Long Horn 14 Pin

6,4 nH**


9

Source: Bookham

Maxi-Chip and similar

2,6 nH**


10

Source: LASER COMPONENTS GmbH

Y-Package

1,6 nH*


11

Lead-loop

5,0 nH***


12

Lead-loop

3,6 nH***


13

Lead-loop

1,56 nH***


With a known stray inductance the fastest possible rise time can be roughly estimated with the following Rule of thumb:

E.g. using a LDP-V 50-100 and a „10-32 coaxial” (#2):

* Manufacturers values. Refer to www.lasercomponents.com for detailed information and package drawings
** Measured values
*** Calculated values