Crosstalk investigation of laser-diode pairs

The crosstalk between the lasers of different laser-diode pairs has been investigated experimentally in the frequency domain. The mutual crosstalk of two lasers diodes monolithically integrated on a single transmitter chip and separated by 100 mu m was measured to be about -50 dB up to a modulation frequency of 100 MHz. At higher frequencies, it rises linearly with the frequency to -40 dB at 1 GHz. Measurements and calculations indicate that the origin of this crosstalk is the leakage current in the chip and inductive coupling of the bond wires. With these crosstalk values, digital data transmission at high bit rates is possible without significantly reducing the receiver sensitivity.<>