Amplitude modulation circuit of laser diode

Abstract

The invention discloses an amplitude modulation circuit of a laser diode. The amplitude modulation circuit comprises a power detection and amplification circuit, a power control circuit, an error voltage amplifier and a laser diode driving circuit, wherein the power control circuit is connected with the error voltage amplifier, and the error voltage amplifier is also connected with the power detection and amplification circuit and the laser diode driving circuit. In the amplitude modulation circuit of the laser diode, the working current of the laser diode can be adjusted in real time by the adoption of a real-time power feedback mechanism, the influence of the laser diode due to temperature, modulation frequency, luminous efficiency, aging and the like is eliminated, the output power of the laser diode is maintained to follow change of control power all the time, the working temperature range and the working linear region of the laser diode are expanded, and the whole service lifetime of a product is prolonged.

Description

technical field [0001] The invention relates to a modulation circuit, in particular to a laser diode amplitude modulation circuit. Background technique [0002] Applications such as phase laser ranging, cable television and laser communication all require continuous wave amplitude modulation (AMCW) on the output optical power of the laser diode (LD). Laser diodes have threshold characteristics, and their threshold current is related to temperature, modulation frequency and aging conditions, and the luminous efficiency of laser diodes is also related to temperature, which affects the stability of laser diode output optical power; in order to maintain the stability of laser diode output optical power, generally Adopt automatic temperature control (ATC) technology or automatic power control (APC) technology. Since temperature control has the disadvantages of high power consumption and large size, automatic power control technology is commonly used in applications that do not h...

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Problems solved by technology

The working current of the laser diode in this modulation method is compensated and can work in a relatively large temperature range. However, only the average power of the laser diode is fed back, and the modulation power generated by the modulation current is not fed back, so there are the following disadvantages: 1. The external differential molecular efficiency of the laser diode becomes smaller and smaller with the increase of temperature, which causes the modulation power amplitude of the laser diode to decrease with the increase of temperature; 2. Above the threshold current, the P-I linear region of the laser diode is generally very small, so Severe non-linear distortion of modulation waveform

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