Fiber Optic Collimator Market Overview
Stephen Montgomery, ElectroniCast

              This is an overview of the ElectroniCastfs Global Market Forecast of use (consumption) of collimator lens and lens assemblies in optical communication components.  Fiber optic collimators are fundamental element and essential for the successful implementation of most components used for optical communications and broadband networks.  These lenses are widely used to covert a divergent output laser beam from an optical fiber or waveguide into an expanding beam of parallel light.  Collimator lenses and lens assemblies are used in a variety of photonic products; However this article will discuss the use in optical communication components, such as modulators, transmitter and pump laser modules, switches, isolators/circulators, DWDM filter modules, coupler/filter modules and components that use integrate component functions.

            Last year, we viewed the Fiber Optics industry as remaining in a recovery mode, from the gbusth of the industry during the years 2000-2002.  Currently, DWDM, hGreen-Fieldh (new-builds), and the glighting-uph of hDARK FIBERh and other relative deployments are beginning to cause a slight and eventual increase in the consumption of the all-optical elements and components that will facilitate a strong environment for the use of grin-lenses or aspheric lenses used for fiber optic collimators (stand-alone lenses and/or lens pigtail/assemblies.  All of this activity will be driven by the expansion of fiber optic transport and access networks, mainly in telecommunications.  The application areas such as military/aerospace, private data communication, cable TV, as well as the specialty/instrumentation market segments, also will drive the use of fiber optic collimators.

            Currently, in year 2006, consumption value of collimator lens is led by use in passive optical components, such as couplers, filters, isolators/circulator and switch elements; however, active/miscellaneous functions such as transmitter laser modules, pump laser diode modules and integrated components that incorporate 2 or more functions (passive + active or active only) in the same component/module are increasing in consumption value.  NOTE: Typically, collimator lenses are used in collimator lens assemblies that are then used in conjunction with active and/or passive components. Since 2003, the number (quantity) of collimator lenses used (consumption) in the selected optical communication components, worldwide, has been increasing at an average annual growth rate of over 25 percent and is forecasted to reach over 100 million units by 2008. Collimator lenses used in active/miscellaneous components, in 2003, held a relative global market value share of 12.7 percent or $11.75 million of the total collimator lens consumption value of  $92.38 million.  By year 2008, the consumption of collimator lens in active/miscellaneous components will increase to $17.70 million (see Figure 1). Passive optical components will tend to increase, however will demand less expensive lenses and/or other solutions. This increase in product demand will be aided by the lower labor cost regions, which also have strength in precision assembly and test, such as Korea, Taiwan, China, plus outsourced assembly by North American and vendors from other regions. During the forecast period (2003-2008), as Bandwidth Expansion demands push for new network links, incorporating Metro/Access, Long-Haul, WDM, OADM and other system-based deployments.

Figure 1

Global Market Consumption Value Forecast of Collimator Lens
Used in Selected Optical Communication Components, Segmented by Product Category Use (US$, Million)

Almost all known collimator lenses have been used to construct fiber optic collimators lens Assemblies (the collimator lens used in a package, holding the lens and joining an optical fiber). Lenses include fiber lenses, ball lenses, aspherical lenses, spherical singlets and doublets, GRIN (GRaded INdex) lenses, microscope objectives, cylindrical lenses, no lens at all as in the case of thermally expanded core (TEC) fiber. Lens materials can vary from glass to plastic to silicon. By a large margin, most of the fiber optic collimators used today are made using GRIN lenses. However, aspherical lenses provide high optical signal processing efficiency with high polarization preservation with the capability of handling high-powered laser sources.

Fiber optic collimators are used in several of the components used in optical fiber amplifiers.  For example, Optical Fiber Amplifiers (OFAs), along with other component used in OFAs accounted for a sizable use of couplers (Taps and WDM).

Approximately half the final value of optical fiber amplifiers consists of optical and electronic components used in their fabrication. The balance of the sales price consists of assembly and test labor/overhead cost, general/sales/administrative overhead, and profit. The largest contributor to component value is the pump laser diodes for fiber amplifiers. Numerous other components also are required, however, as illustrated in Figure 2.

Figure 1.2.1
Optical Fiber Amplifier Component Categories

            Component Consumption Captive Share Substantial     Pump laser diode modules are a major contributor to the final amplifier value; therefore there will be a strong tendency for the largest optical fiber amplifier producers to produce their own laser diode modules (often including producing their own laser diode chips). Other components, such as isolators and optical couplers, will have most of their value in merchant market units purchased by optical fiber amplifier producers.

            All cost elements of optical fiber amplifiers will drop as production quantities increase. Component prices, however, especially laser diode module prices, will drop. Beyond 2010, fiber amplifier production lots will reach a level that justifies substantial automation of assembly and testing. The increasing integration of related components (such as isolator/WDM/tap coupler) also will reduce final assembly costs.  The increase in the number of pump laser diodes per gain block, over the forecast, will be caused by the increase of DWDM. In addition, with the increase of the number of pump laser diodes, brings the need for an increased use of couplers and specialty fiber.

            Another major consumer of fiber optic collimators will be a DWDM filter module.  To separate wavelengths out of a fiber, for routing to its destination, requires optical filters. Optical filters cause attenuation and wavelength selection of the light. Generally, the closer the wavelength spacing, and the greater the number of wavelengths multiplexed, the higher the loss caused at each wavelength transmitted. Dense WDM (Wavelength Division Multiplexing) is made feasible mainly by the availability of optical fiber amplifiers, which compensate for the loss caused by the filters and fibers. Optical fiber amplifiers, however, bring their own problems of differential gain and noise.

            Much of the R&D, therefore, has been directed toward improving filter characteristics: lower loss at the pass wavelength, narrower pass bandwidth with flatter bottom and steeper sides of the filter characteristic.

              Earlier optical fiber amplifiers (OFAs) had substantial variation in their optical gain, across the wavelength band used for WDM. Thus, at the amplifier output, different wavelengths that were at comparable power levels entering the amplifier were at substantially different power levels exiting. The problem is compounded when amplifiers are cascaded, as in trunks of several hundred kilometers. Much of the recent R&D effort, therefore, has been directed at achieving flatter gain characteristics across the band. Gain flattening filers help to serve this purpose.

              For dense (closely spaced at 1.6nm or less) WDM to function, it is essential that the transmitted wavelengths not drift away from their assigned wavelength. The transmitters, therefore, must both be capable of emitting at the assigned wavelength, with very tight wavelength stability tolerance, and also to continually maintain optical power. Substantial effort has been directed at improving designs and fabrication techniques, to achieve more precise, gto orderh wavelengths, and to be highly stable. Currently, a common technique for achieving the assigned wavelength desired is to provide a temperature control element, adjusting the laser diode to the desired wavelength by adjusting its junction temperature. However, this approach is viewed as a negative by some Original Equipment Manufacturers (OEMs) of DWDM Systems, since the heater requires electricity, making the unit an gactiveh device.

            Many current dense WDM systems combine the various wavelengths transmitted, into the single fiber, by a conventional passive optical splitter/combiner. This device has no wavelength selectivity. Thus, if the temperature control of a transmitter diode fails, the transmitter wavelength can wander across other assigned wavelengths, into other assigned channels, superimposed on other signals and creating chaos in the network. System designers have a strong interest in component improvements to move away from dependence upon temperature control. Another technique to achieve stable wavelength emission includes the incorporation of either an internal (monolithic) or external grating (for example: fiber, holographic, ruled, lithographic).