A parallel optical communications device is a device that has multiple transmit (TX) channels, multiple receive (RX) channels, or both. A parallel optical transceiver device is a parallel optical communications module that has multiple TX channels and multiple RX channels in the TX and RX portions, respectively, of the transceiver device. The TX portion comprises components for transmitting data in the form of modulated optical signals over multiple optical waveguides, which are typically optical fibers. The TX portion includes a laser driver circuit and a plurality of laser diodes. The laser driver circuit outputs electrical signals to the laser diodes to modulate them. When the laser diodes are modulated, they output optical signals that have power levels corresponding to logic 1s and logic 0s. An optics system of the transceiver module focuses the optical signals produced by the laser diodes into the ends of respective transmit optical fibers held within a connector that mates with the transceiver module.
The RX portion includes a plurality of receive photodiodes that receive incoming optical signals output from the ends of respective receive optical fibers held in the connector. The optics system of the transceiver module focuses the light that is output from the ends of the receive optical fibers onto the respective receive photodiodes. The receive photodiodes convert the incoming optical signals into electrical analog signals. An electrical detection circuit, such as a transimpedance amplifier (TIA), receives the electrical signals produced by the receive photodiodes and outputs corresponding amplified electrical signals, which are processed in the RX portion to recover the data.
Many parallel optical communications devices are configured to be inserted into an opening of a cage. The cage is typically mounted to an upper surface of a printed circuit board (PCB). The PBC typically has one or more integrated circuits (ICs) and other electrical components mounted on it. One of the ICs mounted on the PCB is typically a controller IC that is electrically interconnected by electrically conductive traces on the PCB to electrical contacts on the parallel optical communications device. In this way, the controller mounted on the PCB and the electronics of the optical communications device are able to communicate with one another. Often times, multiple cages are mounted in receptacles formed in a front panel of a rack, with each of the cages having a respective parallel optical communications device secured thereto. This type of mounting configuration is commonly referred to as an edge mounting configuration.
There is an ever-increasing demand in the optical communications industry for optical communications devices that are capable of simultaneously transmitting and/or receiving ever-increasing amounts of data. As the bandwidths of optical communications devices increase, the amount of heat that is produced by the electronics of the devices also increases. Therefore, in such devices, heat dissipation systems, commonly made up of one or more heat sink devices, are needed to dissipate the relatively large amounts of heat produced by the parallel optical communications devices. For example, one known type of parallel optical transceiver device is a two-by-twelve optical transceiver device having twelve transmit channels and twelve receive channels, with each transmit channel and each receive channel transmitting and receiving data, respectively, at a rate of about 10 Gigabits per second (Gb/s). This type of parallel optical communications device produces a relatively large amount of heat (e.g., 5 watts). In order to prevent the heat produced by these devices from degrading the performance of the devices, heat dissipation systems are needed.
FIG. 1 illustrates a perspective view of a cage 2 that is manufactured by a company called Molex Incorporated of Lisle, Ill. The cage 2 is generally rectangular in shape and has a cage housing 3 that has a length, L, a width, W, and a height, H. A receptacle 4 is formed in the cage housing 3. The receptacle 4 is configured to mate with a two-by-twelve optical transceiver device (not shown) of the aforementioned type, which is sometimes referred to in the industry as a CXP optical transceiver device. The cage housing 3 is made of a metal material and is designed to interconnect with an electrical cable having copper contacts and copper wiring. Because the copper wiring and contacts are thermally conductive, some of the heat produced by the electrical circuitry of the parallel optical transceiver device is transferred into the copper wiring and contacts and is dissipated therein and in the jacket of the cable. In addition, the cage 2 has openings 6 formed in a metal lid 5 that dissipate some of the heat transferred into the housing 3. The cage 2 does not include any heat sink devices and no other provisions for dissipating heat are provided.
For parallel optical transceiver devices of the type described above that have large numbers of channels (e.g., twelve transmit channels and twelve receive channels), the heat dissipation characteristics of the cage 2 are inadequate for dissipating the relatively large amounts of heat that can be produced by the electrical circuitry of the parallel optical transceiver devices. Accordingly, a need exists for a heat sink device for use in combination with a cage that is adequate for dissipating relatively large amounts of heat produced by a parallel optical communications device secured to the cage.