Optical receiver with low-pass filter and mlse unit, and optical communication system implementing the optical receiver
AssigneeSumitomo Electric Industries, Ltd.
InventorTakatoshi Kato
Life of this patent
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Abstract
An optical receiver is disclosed in which the error rate for the received data may be effectively reduced even for the non-linear optical transmission system that provides a directly modulate laser diode as the optical transmitter and the single mode fiber inevitably accompanying with the dispersion as the transmission medium. The optical receiver includes a photodiode (PD), a low-pass filter (LPF) and a maximum likelihood sequence estimator (MLSE) carrying out the Viterbi algorithm. The LPF in front of the MLSE effectively suppresses the ringing appeared in the received signal to generate a replica data with good reproducibility.
Claims10
An optical receiver coupled with a single mode fiber with dispersion, said single mode fiber being coupled with an optical transmitter that includes a directly modulated semiconductor laser diode (LD) as a light source, said optical receiver comprising:
- a semiconductor photodiode (PD) configured to receive an optical signal from said single mode fiber and to convert said optical signal into an electrical signal;
- a low-pass filter (LPF) attributed with a cut-off frequency, said low-pass filter receiving said electrical signal and outputting a filtered signal;
- and
- a maximum likelihood sequence estimator (MLSE) configured to generate an estimated signal based on said filtered signal.
An optical communication system, comprising:
- an optical transmitter that includes a semiconductor laser diode (LD) directly modulated by an LD driver, said LD emitting light with substantial chirping;
- a single mode optical fiber as a medium to transmit said light emitted from said optical transmitter, said single mode fiber showing substantial dispersion;
- and
- an optical receiver including a semiconductor photodiode (PD), a low-pass filter (LPF) attributed with a cut-off frequency, a maximum likelihood sequential estimator (MLSE) and a clock data recovery (CDR), said PD receiving said signal light transmitted from said single mode fiber and converting said signal light into an electrical signal, said LPF receiving said electrical signal and outputting a filtered data, said MLSE receiving said filtered data and generating an estimated data most likelihood of said filtered data, said CDR recovering a clock data contained in said estimated data.
Dependencies are inferred from the claim text.