A method for judging the best working voltage of 10g EPON avalanche photodiode APD

Abstract

The invention discloses a method for judging the optimum working voltage of an avalanche photodiode APD of 10G EPON, comprising the following steps: S1: Obtaining the reverse breakdown voltage V of the APD according to the test data of BOSA or the RSSI under the condition of no light br ;S2: Set an initial working bias voltage, select a fixed input optical power, test the current bit error rate or number of bit errors according to the preset duration, and then increase the working bias step by step with the set step value and repeat Test, test at least 3 points until the bit error rate or the number of bit errors increases; S3: Set the working bias as x and the bit error rate as y, and solve the quadratic equation y=ax 2 +bx+c, get a, b, c three coefficients; S4: According to the obtained a, b, c three coefficients, calculate the extreme value to get the corresponding APD DAC; S5: use the APD DAC value for sensitivity test, if qualified If passed, the APD DAC at the current temperature is subtracted from the corresponding temperature value in the APD DAC LUK table and updated to the APDDAC LUK after translation. If it fails, it fails.

Description

technical field [0001] The invention relates to the field of photodiodes, in particular to a method for judging the optimum working voltage of an avalanche photodiode APD of 10G EPON. Background technique [0002] APD improves performance on the basis of PIN photodiodes. Compared with PIN photodiodes, a layer of P-type material is added after the I layer. When the voltage is low, most of the voltage falls in the PN+ region. When the voltage increases, the width of the depletion region increases until the voltage on the PN+ junction is lower than the avalanche breakdown voltage by 5% to 10%. The I layer is the light absorption region, where photons generate photocurrent, and the PN+ region is the avalanche region. After the photocurrent enters, it is impacted and ionized under the action of a high electric field to generate secondary hole-electron pairs, and the secondary holes may collide and ionize again. This may generate dozens or hundreds of new hole-electron pairs, the...

AI Technical Summary

Problems solved by technology

[0003] The structure of APD results in higher sensitivity than PIN photodiodes, but the circuit is also more complex and requires additional high-voltage drive

Generally, APD has an optimal working voltage. If the multiplication factor M is smaller than this working voltage, the sensitivity will decrease; if it is higher than this working voltage, the multiplication factor will become larger and the noise will also be amplified, the signal-to-noise ratio will be lower, and the sensitivity will also decrease.

Usually, the operating voltage is set according to experience, such as less than the reverse breakdown voltage of 3V or 0.9 times the reverse breakdown voltage, but in special cases it is necessary to find the best sensitivity point, but there is a certain deviation between the empirical value and the optimal value, which cannot be used as best working voltage

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