JP2893773B2 - LD module - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LD module having a function of monitoring the output of an LD chip using a PIN diode. For LD modules with large variations.

[Conventional technology]

Conventionally, in this type of LD module, the optical system including the LD chip is individually adjusted by an automatic output control (APC) circuit for coarse adjustment.
Adjustments were made according to the monitor output of the D module.

[Problems to be solved by the invention]

Since the monitor output of the above-described conventional LD module varies greatly depending on the individual LD module, there is a disadvantage that it is necessary to adjust the APC circuit according to the characteristics of each LD module.

[Means for solving the problem]

An LD module according to the present invention includes an LD chip, a PIN diode chip that monitors a monitor output of the LD chip, an A / D converter that receives the PIN diode chip output, and an input that receives the output of the A / D converter. And a D / A converter that receives the output of the ROM and outputs an LD module monitor signal.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention.
In this embodiment, an LD chip 1, a PIN diode chip 2 for monitoring a monitor light 101 of the LD chip, an A / D converter 3 for changing a PIN diode chip output 102 to a digital signal,
A ROM 4 that gives an address with a digital signal output from the A / D converter and outputs data that has been written in advance at that address, and a D / A converter that converts the digital signal of this ROM output into an analog signal and outputs it as a monitor signal 105 Vessel 5.

When the optical system of the LD module is roughly adjusted, the variation of the monitor output 102 from the PIN diode 2 with respect to the reference output 100 from the LD chip 1 increases depending on each LD module. In other words, even if the output 100 of each LD module is fixed, the individual LD module optical systems are coarsely adjusted, so that the variation of the PIN diode output 102 is large depending on each LD module. The relationship between the optical output and monitor output of this LD module is LD
A / D converter 3, ROM 4 and D / A converter are added to perform measurement at the time of adjusting the optical system of the module.
Can be written to the ROM 4 such that the constant becomes constant. The monitor output 102 of the PIN diode 2 is A / D converted, and the address of the ROM 4 is designated by this digital signal. Is written in advance. By performing the same for each level of the LD chip output, even if the optical system of the LD module is roughly adjusted, it is possible to eliminate the variation between the optical output level and the monitor output.

〔The invention's effect〕

As described above, according to the present invention, an A / D converter, a ROM, and a D / A converter are added to an LD module having a large variation in monitor output, and data corresponding to individual characteristics of the LD module is written in ROM data in advance. This makes it possible to easily adjust the APC circuit including the LD module by making the monitor output constant.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention. 1 ... LD chip, 2 ... PIN diode chip, 3 ... A
/ D converter, 4… ROM, 5… D / A converter, 10… LD module, 100… LD module light output, 101… LD chip monitor light, 102… PIN diode monitor output, 103,104
…… Digital signal, 105 …… LD module monitor output.

Claims (1)

(57) [Claims] 1. A laser diode (LD) module, comprising: an LD chip; a PIN diode chip for monitoring monitor output light of the LD chip; and an A / D converter for converting the output of the PIN diode chip from analog to digital. An LD module comprising: a ROM having the A / D conversion output as an address input; and a D / A converter for converting the ROM output from digital to analog and outputting an LD module monitor signal.