| 摘要 |
The present invention is a PIN photodiode having a substantially elliptical cross section active area. To this end in order to effect the transmission and reception of high data rate transmissions, the switching speeds of digital signals themselves must be great. As can be readily understood, the faster the switching speed of the digital pulse that is required, the less tolerance there is for the ill-effects of RC transience that are often intrinsic properties of semiconductor detectors. One major component of the transient tails is the intrinsic capacitance of the device. Accordingly, it is important to high data rate transmission (fast rise and fast fall times) to reduce as greatly as possible the intrinsic capacitance of the device. Accordingly, what is needed is a maximization of the active area of the device. What this means is a geometric match of the active area that most closely replicates the cross-sectional geometry of the optical beam impingent on the detector. In many applications in fiber optic communications, light is reflected off of a surface at an angle and accordingly light of circular cross section is reflected and emerges with elliptical cross section. What has been done in the past is to make sure that the cross section of the active area of the detector, usually circular, has been great enough to enable light of elliptical cross section reflected from a surface to be impingent upon the circular area of the detector. This means usually that there is "unused" area in the active area of the detector. Because a PIN device is intrinsically a capacitor this "unused" area merely increases the intrinsic capacitance of the detector, an unacceptable result in high frequency data transmission. |
