Bias circuit of electroabsorption modulated laser

Abstract

The invention provides a bias circuit of an electroabsorption modulated circuit. The bias circuit comprises a light emitting assembly TOSA (Transmitter Optical Sub Assembly), a conversion charge pump with nonadjustable output voltage or a switch tube chip, an operation amplifier, and a feedback resistor, wherein the light emitting assembly TOSA is composed of an electroabsorption modulator EA, a semiconductor laser LD and a monitor diode PD, which have a common grounded cathode; the anode of the semiconductor laser LD is connected with a power supply Vcc through a first current limiting resistor; the conversion charge pump or the switch tube chip has a positive power pin connected with the power supply Vcc, a grounded negative power pin, and an output pin connected with one end of a first inductor; the other end of the inductor is connected with the anode of the monitor diode PD and with one end of a third filter capacitor; the other end of the capacitor is grounded; the operation amplifier has a positive power pin connected with the power supply Vcc, a negative power pin connected with the anode of the monitor diode PD, a grounded positive input pin, a negative input pin connected with an external bias unit through a loop resistor, and an output pin connected with the anode of the electroabsorption modulator EA; and the feedback resistor is connected between the negative input pin and the output pin of the operation amplifier.

Description

technical field [0001] The invention relates to an externally adjusted laser bias circuit, in particular to an electric absorption modulated laser bias circuit. Background technique [0002] In order to realize the transmission of data on the optical fiber, the signal needs to undergo electro-optical conversion and photoelectric conversion through the optical fiber transceiver, and the electro-optical conversion is completed by the semiconductor laser. According to different modulation methods, semiconductor lasers are mainly divided into two types: direct modulation lasers and external modulation lasers. In medium and long-distance transmission, externally modulated lasers are mainly used. Although this type of laser has a complex structure and high cost, it can obtain a large dispersion tolerance value, and the transmission distance is mostly more than 40 kilometers. Externally modulated lasers include: electroabsorption modulated lasers and lithium niobate modulated las...

AI Technical Summary

Problems solved by technology

However, the negative voltage ripple output by this method is relatively large, which is easily affected by external interference, resulting in instability of the entire electro-absorption modulation laser bias circuit.

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