Impedance of laser diodes Inductive behavior
Associated products: LDP-AV, LDP-V, LDP-C The parasitic inductive behavior is the most important influence on the pulse rise time.
The output voltage of the driver must be able to charge the leakage inductance, resulting in slower current rise times.
The following table shows the leakage inductance of commonly used laser diode packages.
Housing drawing
Housing designation
Housing 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 leakage inductance, the fastest possible rise time can be roughly estimated using the following formula:
E.g. using a LDP-V 50-100 and a „10-32 coaxial” (#2):
* Values from the manufacturer.
More information and housing drawings can be found at www.lasercomponents.com ** Measured values *** Calculated values
