External modulator monitoring device and external modulator monitoring method

An external modulator monitoring device for monitoring an external modulator, comprising:na mixing unit to mix optical signals modulated by the external modulator and optical signals not modulated by the external modulator, so as to obtain a multiple branches of mixed optical signals;an electrical differential unit to convert the multiple branches of mixed optical signals into corresponding multiple branches of electrical signals, and perform a differential processing on voltages of the multiple branches of electrical signals to obtain differential signals; anda power detection unit to detect power of the differential signals;whereinnthe mixing unit is a 3×3 optical coupler to mix optical signals modulated by the external modulator and optical signals not modulated by the external modulator into three branches of mixed optical signals;the electrical differential unit is a differential filter unit comprising:three photovoltaic transformers respectively to convert the three branches of mixed optical signals into electrical signals, so as to obtain three branches of electrical signals;three filters respectively to filter the three branches of electrical signals, so as to obtain three branches of filtered electrical signals;three differential units to obtain differences between the voltages of every two branches of filtered electrical signals among the three branches of filtered electrical signals, so as to obtain three branches of differential signals,the power detection unit comprising:three squarers respectively to square the three branches of differential signals, so as to obtain three branches of square values; andan adder to obtain a sum of the three branches of square values.

An external modulator monitoring device for monitoring an external modulator, comprising:na mixing unit to mix optical signals modulated by the external modulator and optical signals not modulated by the external modulator, so as to obtain a multiple branches of mixed optical signals;an electrical differential unit to convert the multiple branches of mixed optical signals into corresponding multiple branches of electrical signals, and perform a differential processing on voltages of the multiple branches of electrical signals to obtain differential signals; anda power detection unit to detect power of the differential signals;whereinnthe mixing unit is a 3×3 optical coupler to mix optical signals modulated by the external modulator and optical signals not modulated by the external modulator into three branches of mixed optical signals;the electrical differential unit is a differential filter unit comprising:three photovoltaic transformers respectively to convert the three branches of mixed optical signals into electrical signals, so as to obtain three branches of electrical signals;three differential units to obtain differences between the voltages of every two branches of electrical signals among the three branches of electrical signals, so as to obtain three branches of differential signals,three filters respectively to filter the three branches of differential signals, so as to obtain three branches of filtered differential signals;the power detection unit comprising:three squarers respectively to square the three branches of filtered differential signals, so as to obtain three branches of square values; andan adder to obtain a sum of the three branches of square values.

An external modulator monitoring method for monitoring an external modulator, comprising:nmixing optical signals modulated by the external modulator and optical signals not modulated by the external modulator, so as to obtain a multiple branches of mixed optical signals;converting the multiple branches of mixed optical signals into corresponding multiple branches of electrical signals;performing a differential processing on voltages of the multiple branches of electrical signals to obtain differential signals; anddetecting power of the differential signals;whereinnthe mixing mixes optical signals modulated by the external modulator and optical signals not modulated by the external modulator into three branches of mixed optical signals;the performing comprising:respectively converting the three branches of mixed optical signals into electrical signals, so as to obtain three branches of electrical signals;respectively filtering the three branches of electrical signals, so as to obtain three branches of filtered electrical signals;obtaining differences between the voltages of every two branches of filtered electrical signals among the three branches of filtered electrical signals, so as to obtain three branches of differential signals,the detecting comprising:respectively squaring the three branches of differential signals, so as to obtain three branches of square values; andobtaining a sum of the three branches of square values.