External modulation technology, with the laser working in direct current, has the advantages of no laser chirp, low dispersion distortion, large extinction ratio, and high speed. It also has the disadvantages of high cost and high difficulty in manufacturing.
Direct modulation will lead to high laser chirp (Laser's bias current is modulated by signal and the optical spectrum shifts and shakes). Laser chip will interact with dispersion effect caused by standard single mode fiber (SMF-28), which will generate serious distortion in the place of 1550nm. This kind of distortion will become more serious with the increase of transmission distance, bandwidth and channel number.
At present, international high performance 1550nm direct modulation has no obvious performance inferior while transmitting an analog and digital multiplexing full channel signal with transmission distance≤15Km or transmitting digital load with transmission distance≤40Km.
Huatai HT1500A is a 1550nm direct modulation optical transmitter with high index and AGC function. It adopts high linearity and low chirp DFB laser, built-in pre-distortion compensation and AGC, APC, ATC closed loop control, which improves the system index obviously. HT1500A direct modulated optical transmitter can be used in FTTx (≤10Km) of second-grade service area (Sub-HE), also can be used in WDM narrow-band multiplexing and IP/QAM.
HT1500AC optical transmitter: CATV wavelength.
HT1500AU optical transmitter: ITU standard wavelength.
Low chirp, high linearity DFB laser, chirp compensation.
Dual module RF driver , high efficient laser pre-distortion adjustment.
Full-automatic OMI control, AGC & MGC.
Intuitionistic modulation status display.
Built-in dual back-up power supply, switch automatically .
Casing temperature auto-control, ensure the long life of the laser.
Provide IPTV, VOD value-added service in second-grade service area (Sub-HE).
Analog digital mixed transmit <15Km
(common distance ≤ 10km).
Pure digital load <40Km.
WDM narrow band multiplex >70Km.