Patent Application
20070098332
Many of the commonly used components for fiber optics in the telecom industry have little standardization. Such components, which include diode lasers, 2.5/10 G internally and externally modulated distributed feedback (DFB) lasers, electro-absorption modulated lasers tunable lasers, semiconductor optical amplifiers, LiNbO3 modulators, and detectors, are typically contained in some form of housing. The housings may be specifically designed for a laser and can be a relatively lower volume and higher cost package than some other types of packages. One common package for a variety of laser modules is a 14-pin butterfly package body style. Because there is no standard, there are many variations of 14-pin butterfly packages on the market.
Recently, as fiber-based telecommunication technology is approaching the last mile to finally reach consumers from long haul to metro to building, there are increased pressures for cost reduction for the components and subsystems. Multi-source agreements (MSAs) are being formed among leaders of telecom industry, but often there is more than one MSA for one type of product or form factoring. In contrast, the semiconductor industry has more standardization processes and has become a mature industry. A standardization body of the Electronic Industries Alliance trade association is JEDEC (Joint Electron Device Engineering Council). It was created in 1958 to form discrete semiconductor device standards, and was expanded to include integrated circuits in 1970.
For high power laser modules used in both telecom, non-telecom, and military applications, the package body has to be able to handle much more power than a conventional 14-pin butterfly package used in telecom applications. The leads for such a package typically cannot handle a current of more than 1 A without ohmic heating leading to meltdown. Although modified 14-pin or 8-pin butterfly packages can address this heating problem, the associated piece part cost on an already non-standardized package body makes it expensive to adopt widely. A variety of custom designed package bodies have been created by a range of manufacturers. These are each unique designs not related to any standard or MSA.
In the embodiments described here, existing JEDEC-defined TO- and MO-series packages (e.g., TO-257, TO-254, TO-258, MO-078, TO-267, and MO-079) are used for high power laser module packaging applications. These JEDEC standard packages were designed to house high power rectifying diodes and power MOSFETs, and can handle very high current and voltage. They have become standard package body styles widely used in semiconductor power module applications, and have undergone continued improvement.
An additional benefit of such packages in fiber optic components is that a copper base material is typically used in TO-series packages, and such a base is useful for reducing the thermal impedance and increasing the thermal conductivity of the entire package. Compared with CuW composite material typically used in a telecom 14-pin butterfly package, cooper not only has a higher thermal conductivity, but it is inexpensive and easy to machine.
By using such standardized packages for fiber optic components, a lower cost packaged device can be made. Other features and advantages will become apparent from the following detailed description, drawings, and claims.
Referring to
For the application described here, housing 10 has three leads 12, 14, and 16 extending away from one side of the package, and a hole formed, e.g., by drilling, in another side. A fiber ferrule 18 is mounted at the side for holding an optical fiber at the opening and is positioned and aligned in such a way to allow the fiber to couple light from the optical device. Such positioning and aligning is generally known. The optical device is preferably a pump laser 20, but could be a laser diode, and other fiber optic components can be housed in such a package. Laser 20 has an anode coupled to lead 12, and a cathode coupled to lead 14.
In one embodiment, the pump laser is a 7 W, 915 nm, multi-mode laser, formed with a chip-on-submount (COS). The device can operate without a separate cooling device or system. The laser is mounted using a direct bond copper (DBC) ceramic substrate (e.g., BeO or Al2O3) to provide thermal management.
Other metal packages in the TO and Mo series include TO-254, TO-257, TO-259, TO-267, MO-078, and MO-079. These packages are each generally rectangular with about 10-20 mm on the sides in the case of the TO-packages. Referring to
In each case, these drawings do not depict TO and MO series packages as they would typically be purchased, because they have been modified with a hole and a fiber ferrule for connection to an optical fiber.
Having described embodiments, it should become apparent that modifications can be made without departing from the scope of the invention as defined by the appended claims. For example, while certain devices and materials have been described, it should be apparent that other materials and devices can be used. Some optical devices that can be packaged with the systems and methods described here 600-700 nm diode laser, 780-820 nm diode laser, 900-1070 nm diode laser, 1400-1600 nm diode laser, 2.5/10 G internally and externally modulated distributed feedback (DFB) laser, electro-absorption modulated lasers tunable laser, semiconductor optical amplifiers LiNbO3 modulator, and LiNbO3 detector.
