Cross-Channel Interference Due to Wavelength Drift of Tunable Lasers in DWDM Networks

Abstract

Abstract-The authors present an investigation of the wavelength stability of a tunable laser (TL) transmitter and its impact on the performance of a 2.5-Gb/s dense wavelengthdivision-multiplexed (DWDM) system. Performance of a DWDM system, employing such a TL, is characterized by examining the cross-channel interference caused by this drift when the channel spacing is set to 12.5 and 25 GHz. Results obtained show that the wavelength drift affects the system performance by introducing an error floor in the case of 12.5-GHz spacing. This error floor can be mitigated by increasing the blanking time of the TL during the channel transition, in order to reduce the wavelength drift.Index Terms-Sampled-grating distributed Bragg reflector, tunable lasers (TLs), ultradense wavelength-division multiplexing (UDWDM), wavelength drift measurement.

Characterization of Frequency Drift of Sampled-Grating DBR Laser Module Under Direct Modulation

“…1(a), is taken where the output of the directly modulated TL is detected by a photodiode in conjunction with an oscilloscope. Subsequently, the modulated signal is passed through an OBPF with a 3-dB bandwidth of 26 GHz, detuned by 0.1 nm to create a sloped frequency discriminator [7]. The frequency discriminator essentially assists in characterizing the offset in frequency of the TL, from the set International Telecommunication Union (ITU) reference frequency.…”

Identifying the Contribution of Carrier Shot Noise and Random Carrier Recombination to Excess Frequency Noise in Tunable Lasers

“…Tunable lasers are vital components within every transponder of modern coherent optical communications systems [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19].To date, narrow linewidth tunable lasers, with linewidths~100 kHz based on thermally tuned external cavity lasers, are the tunable laser technology that dominates the market for systems with line rates of 100 Gbit/s, 400 Gbit/s and beyond [7]. The reliance on thermal tuning makes these lasers unsuitable for sub-microsecond wavelength tuning times, as demanded by state-of-the-art transponders for the next-generation passive optical networks (NG-PON2) [2,8].…”

EDFA transient suppression in optical burst switching systems

“…In its basic operation, variable size bursts, containing packets or partial packets, are routed to their respective destinations by selecting the wavelength that carries them. Each OPST port has a packet-responsive tunable transmitter (50 -100 nanosecond tuning time) [4] that sends data packets on the wavelength assigned to the desired destination device. Any port can transmit asynchronously on the same wavelength (i.e.…”