In-wafer testing of DFB semiconductor lasers

Details In-wafer testing of DFB semiconductor lasers In-wafer testing of DFB semiconductor lasers

1999-12-15

2001-07-24

Christianson, Keith (Department: 2813)

Semiconductor device manufacturing: process

Making device or circuit emissive of nonelectrical signal

Having diverse electrical device

C148S033400

Reexamination Certificate

active

06265237

ABSTRACT:

FIELD OF THE INVENTION
The present invention is directed to semiconductor lasers. More particularly, the present invention is directed to the manufacturing and testing of semiconductor optical lasers.
BACKGROUND OF THE INVENTION
All optical communication systems include three major building blocks: a source, an optical fiber, and a detector. The source is usually a semiconductor laser.
A semiconductor laser needs both gain and feedback to operate. A typical laser is manufactured in a semiconductor wafer. When the laser is broken away or “cleaved” from the wafer, cleaved facets are formed on the front and rear of the laser. The cleaved facets provide some or all of the required feedback for the laser. The feedback from the cleaved facets may in some instances be tailored by, for example, adding optical coating.
There are multiple types of semiconductor lasers. One type of laser is referred to as a “Fabry-Perot” laser. A Fabry-Perot laser is a multi-mode laser that receives all of its feedback from its cleaved facets. Another type of laser is referred to as a “Distributed Feedback” (“DFB”) laser.
FIG. 1
illustrates an example of a typical DFB laser
10
. DFB laser
10
includes an active region
16
and front and rear facets
12
and
14
. Facet
12
provides a reflection
13
and facet
14
provides a reflection
15
. DFB laser
10
further includes a diffractive grating
18
. Diffractive grating
18
provides additional reflection
19
and
20
. Thus, DFB laser
10
receives feedback from both its facets and diffractive grating. A DFB laser is a single-mode laser.
The spectral properties of a DFB laser are very dependent on the strength of the interaction of the lasing light with the diffractive grating. The strength of the interaction is referred to as KL.
When manufacturing DFB lasers or other electro-optic devices, multiple devices are typically fabricated on a single wafer. Determining the yield of the wafers generally requires a considerable amount of individual device testing to select or screen “good” performing devices from the devices with inadequate performance or, in some cases, higher grade devices from lower grade ones. Currently most of this testing or screening is done on devices after they have been separated from the wafer and, for a DFB laser, considerable amount of device to device variation is introduced by the cleaved facet itself. The individual device testing, often required on 100% of the devices, adds considerable expense to the cost of high performance laser devices.
Reduction in testing time and cost can be achieved by selecting for subsequent processing only the wafers which are likely to provide the higher yields at testing. Time and inventory could be saved in this wafer certification process if the laser devices could be evaluated or sampled while in wafer form, i.e., prior to separation. Unfortunately, wafer level testing has not been well exploited in laser manufacturing because the light that is so important to the electro-optic properties of the laser quality is generally inaccessible until after the devices have been cleaved and separated from the wafer.
Based on the foregoing, there is a need for a method and system that provides testing of lasers before they are separated from the wafer.
SUMMARY OF THE INVENTION
One embodiment of the present invention is a method of manufacturing and testing a laser device that facilitates in-wafer testing of the laser device. The method includes forming the laser device on a wafer and forming a light detecting device on the wafer adjacent to the laser device. The laser device should include a grating. The method further includes causing the laser device to lase while in the wafer and detecting light generated from the laser device with the light detecting device. Finally, the method includes obtaining an electro-optic parameter of the laser device from the detected light.


REFERENCES:
patent: 5258991 (1993-11-01), Peterson
patent: 5281829 (1994-01-01), Chinen
patent: 5285466 (1994-02-01), Tabatbale
patent: 5891746 (1999-04-01), Kuchta

Affiliated with

Also associated with

Rating

In-wafer testing of DFB semiconductor lasers does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with In-wafer testing of DFB semiconductor lasers, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and In-wafer testing of DFB semiconductor lasers will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2479295