JPH01219574A - Method and device for measuring characteristic of laser diode - Google Patents

Abstract

PURPOSE:To securely protect a laser diode against a surge and to shorten the required measurement time for each diode by short-circuiting both ends of the laser diode at the start and end of electric feeding. CONSTITUTION:One-terminal sides of laser diodes 11, 12..., 1N to be measured are connected to a power terminal through the 1st switch 2 of the N contact of one circuit and a protective resistor 3 and the other-terminal sides are connected mutually and connected to a power terminal 6 through a protective resistor 5. Then it is confirmed that 2nd switches 71, 72...7N connected to the diodes 11, 12..., 1N are closed and then when the diode 11 is measured, the switch 2 is switched to a contact P1 and only the switch 71 among the switches 71, 72...7N is turned off; and a driving current is increased gradually and the characteristics are measured. Then the switch 71 is turned on again after the measurement to protect the diode 11 against a surge current.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method and apparatus for measuring characteristics during the manufacture of semiconductor laser diodes.

Conventional technology semiconductor laser diodes have poor surge resistance characteristics,
It is easily destroyed by a surge of 0 mA to several 100 mA, so in the past, the diode should be measured without connecting it to the current source necessary for characteristic measurement and immediately starting measurement. , measure the characteristics by gradually increasing the current value and passing the required current, and after measuring the characteristics, gradually decrease the current value until it reaches a current value that is not affected by surges, and then reduce the laser diode current. Characteristics are measured by removing it from the source.

Problems to be Solved by the Invention In such a conventional characteristic measuring method, the current value is gradually increased and then gradually decreased when measuring one laser diode, which increases the time required for measurement and requires multiple measurements. It is not suitable for measuring the characteristics of laser diodes.

SUMMARY OF THE INVENTION An object of the present invention is to provide a characteristic measuring method and apparatus that can protect laser diodes from surges and shorten the time required for measuring each laser diode compared to the conventional method.

Means for Solving the Problems The laser diode characteristic measuring method of the present invention short-circuits both ends of a plurality of laser diodes to be measured with a short circuit, and connects the laser diode to the laser diode to be measured. energize the parallel circuit with the short-circuit that was connected to the laser diode, and then measure the characteristics by switching only the short-circuit connected to the laser diode to the open state, and at the end of the measurement, before turning off the energization. The short circuit connected to the laser diode is then returned to a closed state to protect the laser diode from surge current.

The characteristic measuring device of the present invention includes a first switch for selecting a laser diode to be energized from among a plurality of laser diodes to be measured, and a plurality of second switches connected in parallel to the plurality of laser diodes, respectively. It is characterized by being equipped with a switch.

Further, the characteristic measuring device of the present invention includes a first switch for selecting a laser diode to be energized from among a plurality of laser diodes to be measured, and a plurality of switches connected in parallel to each of the plurality of laser diodes. The present invention is characterized in that it is provided with a second switch and a controller that switches the second switch interposed in the laser diode that is energized by the first switch to an open state after a predetermined time delay.

According to this characteristic measuring method, both ends of the laser diode are short-circuited by a short circuit at the start and end of energizing the laser diode, and the short circuit is opened during characteristic measurement.

According to the characteristic measuring device using the first and second switches, both ends of the laser diode are short-circuited by the second switch when starting and ending energization of the laser diode. When measuring another laser diode, the energizing circuit is switched by the first switch.

According to the characteristic measuring device using the first and second switches and the controller, the second switch is automatically opened and closed by the controller in conjunction with the switching operation of the first switch.

EXAMPLES Hereinafter, the characteristic measuring method of the present invention will be explained based on specific examples.

FIG. 1 shows a characteristic measuring device for carrying out the characteristic measuring method of the present invention, in which a plurality of semiconductor laser diodes (hereinafter referred to as diodes) to be measured (hereinafter referred to as diodes) 11°, 12..., one end of IN, here the cathode is , is connected to a power supply terminal 4 connected to a current source via a first switch 2 with one circuit N contacts and a protective resistor 3. The anodes at the other ends of the diodes 11 to IN are connected to each other and connected to a power supply terminal 6 via a protective resistor 5. Second switches 71, 72, . . . are connected to both ends of the diodes 11 to IN, respectively.
7N are connected in parallel.

Now, when measuring the various characteristics of the diodes 11-IN, it is confirmed that the second switches 71-7N are closed, and the power supply terminal 4.6 is connected to a current source (not shown). When measuring diode 11 among diodes 11 to IN, first switch 2 is switched to contact P1 to which the cathode of diode 11 is connected, and then one of the second switches 71 to 7N is switched. Only the second switch 71 connected to the diode 11 is turned off. Thereafter, current is applied between the power supply terminals 4 and 6, and the magnitude of the drive current value at that time is read from the value of the voltage drop across the protective resistor 3 or 5. When this drive current value is gradually increased from zero, the diode 11 reaches a threshold current I.

Above this, it oscillates and emits light. The light emission output at this time is measured by an optical power meter (not shown). After measuring various characteristics of the diode 11 in this way, such as the current (1) vs. optical output (L) characteristics, differential quantum efficiency <dL/di), and current vs. voltage characteristics, the second switch is closed again. As a condition, the diode 11 is protected from surge current.

In the embodiment of FIG. 1, the short circuit is connected to the second switch 71-7.
However, the anode and cathode of the semiconductor laser diode that is waiting for measurement is short-circuited with a lead wire, and after each measurement of various characteristics, the semiconductor laser diode that is being measured except for the semiconductor laser diode that is waiting for measurement is Once the lead wires attached to the semiconductor laser diodes are removed and the measurement of one semiconductor laser diode is completed, the lead wires that were removed during the measurement are shorted again and the characteristics of each semiconductor laser diode are measured in turn. The characteristic measuring method of the present invention can also be carried out by doing the following.

FIG. 2 shows another embodiment for carrying out the characteristic method of the present invention, and parts having the same functions as those in FIG. 1 are given the same reference numerals and will be explained. Note that for the sake of simplicity of explanation, only one semiconductor laser diode is shown.

In FIG. 2, the second switch 71 connected in parallel to the semiconductor laser diode 11 is not a manually operated switch, but an electronic switch 81 that is switched by a control signal S. This electronic switch 81 is connected to a controller 91 to 9N provided for each electronic switch 81 to 8N (82 to 8N is not shown).
It is controlled by a controller 91 of the two. The controller 91 is
It detects that a voltage is applied to the diode 11 via the contact P1 of the first switch 2, and sends a control signal to the electronic switch 81 after a predetermined time delay (about a fraction of a second). Then, the second switch 71 is automatically opened. When the first switch 2 is switched from contact P1 to another position, the controller 91 immediately switches to the second position.
The switch 71 is automatically switched to the make state to protect it from surges. Electronic switch 82 provided for other diodes 12 to IN
-8N and controllers 92-9N are also the same as above.

With this configuration, the electronic switches 81 to 8N are automatically switched in conjunction with the operation of the first switch 2, improving operability. Further, although the configuration is not shown, by automatically switching the first switch 2 according to the order of measurement of each semiconductor laser diode 11 to IN, automatic switching of a plurality of semiconductor laser diodes 11 to IN is performed. Needless to say, measurement is possible.

Effects of the Invention As described above, according to the characteristic measuring method of the present invention, both ends of the laser diode are shorted by a short circuit at the start and end of energizing the laser diode, so the current is gradually increased as in the conventional method. Laser diodes can be reliably protected from surges even if the current is gradually reduced, and the time required to measure each laser diode can be greatly reduced. Suitable for measuring characteristics.

The characteristic measuring device includes a first switch for selecting a laser diode to be energized from among a plurality of laser diodes to be measured, and a plurality of second switches connected in parallel to each of the plurality of laser diodes. When configured,
Characteristics can be measured while protecting the semiconductor laser diode from surges by repeatedly operating the first and second switches, which improves operability compared to manually removing, attaching, and replacing lead wires. , as well as speeding up the measurement.

Furthermore, when the second switch is switched in conjunction with the operation of the first switch by a controller, in addition to the above effects, operability during characteristic measurement is further improved, and the semiconductor laser diode is This improves the reliability of protection from

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a characteristic measuring apparatus for carrying out the characteristic measuring method of the present invention, and FIG. 2 is a block diagram showing another embodiment of the characteristic measuring apparatus. 11-IN... Semiconductor laser diode, 2... First switch, 71-7N... Second switch, 91
...Controller. Agent Yoshihiro Morimoto Figure 1 Figure 2

Claims (1)

[Claims] 1. Both ends of a plurality of laser diodes to be measured are each short-circuited with a short circuit, and the laser diode to be measured is connected to a parallel circuit with the short circuit connected to the laser diode. The short circuit connected to the laser diode that is energized and then connected to the laser diode to be measured is then switched to an open state to measure the characteristics, and at the end of the measurement, the short circuit connected to the laser diode is turned off. A method for measuring the characteristics of a laser diode that closes the short circuit and protects the laser diode from surge current. 2. A first switch that selects a laser diode to be energized from among a plurality of laser diodes to be measured;
A laser diode characteristic measuring device comprising: a plurality of second switches connected in parallel to each of the plurality of laser diodes. 3. A first switch for selecting a laser diode to be energized from among a plurality of laser diodes to be measured;
A plurality of second switches each connected in parallel to the plurality of laser diodes, and a second switch interposed in the laser diode energized by the first switch are opened after a predetermined time delay. A laser diode characteristic measuring device equipped with a controller that switches to