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Thermoelectrics in Telecommunications

Technical innovation and high reliability are critical for our customers in the telecommunications industry. With Coherent’s origin as a supplier to the U.S. defense and space industries, quality and reliability were built into the corporate foundation from the outset. When Coherent considered logical places to expand its business, telecommunications was a clear choice due to the stringent quality and reliability concerns.
 
Today, Coherent is in partnership with multiple tier-one optical component suppliers. We understand the pressures to innovate ahead of the curve, anticipate market demand, scale production for volume orders and deliver tested/reliable solutions priced to fit the market.
 
Coherent delivers the highest quality telecommunications solutions at an off-shore price point. With a broad portfolio of product offerings and customization options, Coherent provides an optimum solution to extend application lifetime and performance.
 
Read more on our Telecommunications applications:
 
Transmission Lasers (DWDM)
The telecommunications market often uses thermoelectric coolers (TECs) to temperature-stabilize semiconductor laser diodes. Laser diodes, called transmission lasers, transmit digital information over fiber optic cables. In Dense Wavelength Division Multiplexed (DWDM) systems, different wavelengths occupy the same fiber optic cable and must not be allowed to drift on top of each other due to changes in temperature. Thermoelectric coolers can either heat or cool the transmission lasers and hence can stabilize their temperature to prevent wavelength drift. Since transmission lasers work nonstop in the field for a minimum of 20 years, the TEC must match the laser’s lifetime and durability both in design and build.
 
Pump Lasers (EDFA)
Within the telecommunications market, a common use for thermoelectric coolers (TECs) is the temperature stabilization of semiconductor laser diodes. A common type of laser diode found in telecom is the 980nm pump laser. These pump lasers act as the source of light energy to excite the atoms inside Erbium Doped Fiber Amplifiers (EDFA). EDFAs are spaced periodically along a span of fiber optic cable to amplify a weak incoming stream of light pulses into a much stronger departing stream. Pump lasers overheat when not in use, decreasing their total lifetime. Coherent’s thermoelectric coolers remove the heat from the laser, thereby reducing the laser’s temperature and significantly increasing its lifetime. Since the pump laser is expected to work nonstop in the field for a minimum of 20 years, the TEC must match the laser’s lifetime and durability both in design and build.
 
Photonic Integrated Circuits (PIC)
The telecommunications market often uses thermoelectric coolers (TECs) to temperature-stabilize Photonic Integrated Circuits (PIC). PICs provide multiple functions built on a common Si or InP platform. PICs will commonly provide functions such as multiplexing several digital light streams, followed by laser transmission of the multiplexed signals, light stream detection and de-multiplexing of incoming signals, optical channel monitoring, wavelength add/drop switching and more. As with all Telcordia components, PICs are expected to work nonstop in the field for a minimum of 20 years; the TEC must accommodate the laser’s lifetime and durability both in design and build.
 
Avalanche Photodiodes (APD)
The telecommunications market often uses thermoelectric coolers (TECs) to temperature stabilize Avalanche Photodiodes (APD). APDs are always reverse biased at a high voltage and therefore subject to excessive noise created by thermal energy. TECs can cool the APD and significantly reduce thermal noise, thereby increasing the APDs signal-to-noise ratio and its ability to differentiate very weak incoming light pulses. As with all Telcordia components, APDs are expected to work nonstop in the field for a minimum of 20 years; the TEC must accommodate the laser’s lifetime and durability both in design and build.
 
CATV Lasers
A common use for laser diodes is the transmission of analog information over fiber optic cables carrying Cable Television (CATV) signals. In CATV systems, different wavelengths can occupy the same fiber optic cable and must not be allowed to drift on top of each other due to changes in temperature. Thermoelectric coolers can either heat or cool the CATV lasers and hence stabilize their temperature to a given point and prevent wavelength drift. Since CATV lasers are expected to work nonstop in the field for a minimum of 20 years, the TEC must accommodate the laser’s lifetime and durability both in design and build.
 
Optical Channel Monitors (OCM)
The telecommunications market often uses thermoelectric coolers (TECs) to temperature stabilize Optical Channel Monitors (OCM). OCMs usually contain some sort of tunable light filter that requires temperature stabilization to perform its task across a broad range of external temperatures. The task of the OCM is to monitor the optical power and wavelength of each of the active wavelengths in a given Dense Wavelength Division Multiplexed (DWDM) system node, so that the wavelength spectrum leaving the node can be amplitude-balanced. As with all Telcordia components, OCMs are expected to work nonstop in the field for a minimum of 20 years; the TEC must accommodate the laser’s lifetime and durability both in design and build.