JPS63121763A - Instrument for measuring characteristics of avalanche photodiode - Google Patents

Abstract

PURPOSE:To measure the breakdown voltage temperature factor of an avalanche photodiode by providing the titled instrument with a bias DC power supply for an avalanche photodiode to be measured, a light source to which output can be varied and a voltage/current measuring instrument for measuring an operating state. CONSTITUTION:A bias voltage is impressed to the avalanche photodiode 1 to be measured by the bias AD power supply 2 and voltage and current between the terminals of the diode 1 are measured by a voltmeter 3 and an ammeter 4. When the optical output of the light source 5 is defined as P1, a multiplication factor M1 can be found out from a dark current in a multiplication area VR1 and the non-multiplication area VR0 of a bias voltage of the diode 1 and a current obtained at the time of light incidence. When the bias voltage is adjusted after measuring the magnification factor M1 so that a magnification factor at an optical output P2 of the light source is M1, the temperature characteristics of a breakdown voltage can be obtained. Thus, the characteristics of the avalanche photodiode can be measured within a short period.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to measuring the characteristics of an avalanche photodiode, and more particularly to a device for measuring the temperature coefficient of breakdown voltage.

[Conventional technology]

Since an avalanche photodiode applies a bias voltage near the breakdown voltage and utilizes the carrier avalanche effect in the PN junction, the temperature coefficient of the breakdown voltage, which changes with temperature, is an important parameter.

Conventionally, this type of measurement has been carried out by placing the avalanche photodiode to be measured in a constant temperature bath 17 where the gold temperature can be changed, and using a DC power supply 14, a voltmeter 15, an ammeter 16, and a breakdown voltage measurement circuit as shown in Fig. 3. A measuring device was used. This device changes the temperature inside the thermostat, for example T1.
('C), breakdown voltage V(B
R) R1 and V(nu)ms were measured, and at this time, the temperature coefficient β of the breakdown voltage was determined as shown in equation (1).

[Problem that the invention seeks to solve]

Since the conventional measuring device described above must measure the breakdown voltage at two or more temperatures, it is necessary to change the temperature within the thermostatic oven. Therefore, in the measurement work, there is a drawback that the measurement time becomes long.

[Means for solving problems]

To achieve this objective, the measuring device of the present invention includes a light source with variable output, a bias power source for the avalanche photodiode to be measured, and a device for controlling its operating current and operating voltage.

The operating principle of the device according to the invention will be explained in detail with reference to an embodiment in FIG.

〔Example〕

FIG. 1 shows an embodiment of the present invention.

1 is an avalanche photodiode to be measured, and 2 is a bias direct fit source thereof. The voltage and current across the terminals of avalanche photodiode 1 are measured using voltmeter 3, respectively.
, can be measured with ammeter 4. 5 is a light source whose output is Pi
and P2. Here, it is assumed that PI<P2.

Assume now that the optical output of the light source 5 is Pl, and the bias voltage of the avalanche photodiode to be measured is set to VRl, which is the multiplication region.

The multiplication factor at this time is Ml. Note that the multiplication factor M1 can be measured as follows.

Dark current at bias voltage VRI and current t when light from the light source is incident - measured by ammeter 4, respectively Idl
, Ipt. Next, change the bias voltage so that it is in the non-multiplying region, and set it to RO. The dark current at this time and the current when light is incident are all measured using an ammeter 4, and are designated as Ido and Ipo, respectively. The multiplication factor M1 is determined by equation (2).

After the multiplication factor M1 is completed, the optical output of the light source 5 is set as P2, and the multiplication factor M2 at the bias voltage VRI is determined in the same manner as above.

That is, M2 becomes as shown in equation (3).

Here, Ip2 and Id2 are the current flowing through the avalanche photodiode to be measured when light from the light source is incident, and the dark current at the bias voltage VRI, respectively.

Under the above conditions, generally Pl<P2 j), Ipt<I
P! Therefore, the relationship between Ml and M2 is as follows. From Ipl<Ipz, the internal temperature of the avalanche photodiode to be measured is greater when the optical output of the light source 5 is P2. Therefore, if the internal temperature is the same, there is almost no difference in the amplification factor Fi, but under the above conditions, a difference occurs in the internal temperature, so the multi-operation point where the breakdown voltage is high shifts. That is, MlO shows a larger value than M2.

The breakdown voltage variation ΔV(BR)R can be expressed by equation (4).

Δ■ (old 1) R = β - ΔT・V (BR) R... (4J
Here, β is the temperature coefficient of breakdown voltage, ΔT is internal temperature rise, and V(an)u is breakdown voltage.

Therefore, by changing the bias voltage by the amount of temperature rise, it is possible to equalize the multiplication factors when the optical output of the light source is changed to Pl and P2.

That is, after measuring the multiplication factor Ml, the temperature characteristics of the breakdown voltage are determined by fully adjusting the bias voltage so that the multiplication factor at the optical output P2 of the light source becomes Ml. The relationship is shown in equation (5).

However, ΔVn = VB2- VRIVntki Bias voltage at light source light output pg J T = Rth -VB2- (Ipz-Ipt)'
pm2=bias voltage (2) At R2, the current at the output P2 of the light source and pth shall be measured in advance using the thermal resistance of the avalanche photodiode to be measured.

〔Example〕

The second diagram is a second embodiment of the present invention. A bias voltage is applied from the DC power supply 7 to the avalanche photodiode 6 to be measured. The current and voltage flowing through this avalanche photodiode are measured by an ammeter 9 and a voltmeter 8, respectively. light source 10
The output of is the output P! and P2 change with repetition time. It is assumed that this repetition frequency is sufficiently longer than the thermal constant of the aberration photodiode. Due to this light source, the current flowing through the avalanche photodiode also changes with the incident light, and this current is measured with an oscilloscope 11. Note that the resistor 12 is a resistor for current detection force. The measurement method is the same as in Example 1. In this embodiment, since the output of the light source is changed, there is an advantage that there is no need to switch the light output of the light source.

〔Effect of the invention〕

As described above, the present invention has the advantage that measurement can be performed in a short time by utilizing the relationship between the amplification factor and the bias voltage by changing the amount of light incident on the avalanche photodiode to be measured.

[Brief explanation of the drawing]

FIG. 1 shows one embodiment of the present invention, and FIG. 2 shows a second embodiment. FIG. 3 shows a conventional measuring device. 1.6.13... Avalanche photodiode, 2.7.14... DC power supply, 3, 8, 15°° voltmeter, 4, 9.16... Current Total, 5.10
... light source, 11 ... oscilloscope,
12...Resistance, 17...Thermostat.

Claims (1)

[Claims] It has a bias DC power supply for the avalanche photodiode to be measured, a light source that is incident on the avalanche photodiode and whose output can be varied, and a voltage and current measuring device for measuring the operating state, and the breakdown voltage temperature of the avalanche photodiode. An avalanche photodiode characteristic measurement device that enables the measurement of coefficients.