1550nm externally modulated optical transmitter is the core equipment in this system. RFTV is a unidirectional analogue and digital video broadcast. It adopts high efficiency modulation mode for RF carrier wave and its economy, flexibility and bandwidth validity is beyond comparison of IPTV. Adopting EPON or P2P access mode to realize triple-play, FTTx , RFTV broadcasting network in 1550nm optical transmitter wavelength still plays an important role.

The production of 1550nm Externally Modulated Optical Transmitter needs an expensive LiNbO3 external modulator and a high power, narrow bandwidth, low noise DFB laser, so it has high request for the production technology and is difficult to be adjusted. Compared with the 1550nm Direct Modulated Optical Transmitter, it has the feature of high cost and high price, which restricts many excellent features of external modulator and makes it unable to be widely used in CATV Network. But in recent years, with the improvement of optical components production technology and the decreasing of price, the advantage of high cost performance of 1550nm externally modulator technique has been highlighted.

Huatai is the well-known manufacture in analog externally modulated optical transmitter in the world. HT8500A, an economical 1550nm Externally Modulated Optical Transmitter, is produced specially for middle and small CATV station. Optical transmitter adopts narrow bandwidth (Typ.=1MHz), low noise and continuous wave DFB laser as the light source, adopts CATV special LiNbO3 external modulator to modulate signal, and adopts a series of unique innovation technique to reach the excellent system control. With 47~862MHz bandwidth, CNR ≥ 53dB, CTB ≤ -65dB, CSO ≤ -65dB, SBS: 13, 16, 18adjustable, Optical transmitter can make CATV network transmit video, audio and data with high performance. The machine is equipped with perfect RS232 communication interface, SNMP network management and 1+1 backup power supply.

HT8500AC optical transmitter: Standard type, dual fiber output CATV work wavelength, 1MHz laser line width, SBS 13, 16, 18dBm adjustable, SNMP network management optional.

HT8500AU optical trnasmitter: Standard type, dual fiber output ITU wavelength adjustable, 1MHz laser line width, SBS 13, 16, 18dBm adjustable, SNMP network management optional.

 High performance: Externally modulated technology for optical transmitter, no laser chirp, low dispersion distortion, high extinction ratio, with excellent characteristic within 40~862MHz in-band.

 Narrow bandwidth (Typ.=1MHz), lower noise, DFB continuous wave laser.

 The operating bandwidth of optical transmitter is up to 47~1080MHz.

 Perfect index: Unique innovation technology, provide excellent CNR, CTB, CSO & SBS.

 ITU standard wavelength adjustable, the user can adjust and set the laser wavelength on the front-panel with ±0.05nm stepping in the range of ±200GHz (±1.6nm), used in the network upgrading and expansion of WDM system.

 AGC/MGC mode is optional at spot. OMI can be optimized at spot.

 Perfect RS232 communication interface.

 SNMP network management function optional.

 1+1 backup power supply optional.

 Casing temperature auto-control.

 Excellent P/P ratio.

 Used in middle and small CATV center head end, solve the transmission of trunk and distributive network with high quality and low cost.

 Used in second-grade service area of sub-station. With excellent P/P ratio, provide second-grade users with high quality and high reliability value added service such as RFTV, IPTV, VOD and so on. It can avoid the limitation on transmission bandwidth and distance as well as system CSO deterioration caused by laser chirp for adopting 1550nm direction modulated optical transmitter.

 FTTH application diagram

 HT8500A optical transmitter is typically used in the sub-station full optical relay for spotting local program and providing IPTV, VOA value-added business.

 Applied in second transmission of sub-station (FTTx), supply with IP/QAM, VOD VAS