Separate absorption and multiplication (SAM) APDs have been widely deployed in long-wavelength, high-bit-rate optical transmission systems. At high bit-rates (10 GBit/s), however, the bandwidth and the gain-bandwidth-product of the SAM APDs has become a limitation. Recently, we have developed a resonant-cavity SAM APD structure that circumvents both of these performance limitations. Since the quantum efficiency is decoupled from the transit time in the resonant-cavity structure, bandwidths 20 GHz have been achieved in the low-gain regime. At high gains, the response of an APD is determined by the gain-bandwidth-product. The use of very thin multiplication layers in the resonant-cavity structures has led to low noise (/spl beta///spl alpha/=k0.25) and gain-bandwidths as high as 180 GHz. The external quantum efficiency of these resonant-cavity SAM APDs is about 80 %, resulting in a record bandwidth-efficiency product as well. The breakdown voltage (V/sub b/) is 15 V and the dark current is 10 nA at 90% V/sub b/.
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机译：单独的吸收和倍增（SAM）APD已广泛部署在长波长，高比特率光传输系统中。然而，在高比特率（<10 gbit / s）处，带宽和SAM APD的增益带宽 - 产品已成为限制。最近，我们开发了一个谐振腔SAM APD结构，这些结构避免了这些性能限制。由于量子效率从谐振腔结构中的过渡时间分离，因此在低增益状态下已经实现了带宽<20GHz。在高收益中，APD的响应由增益带宽 - 产品决定。在谐振腔结构中使用非常薄的乘法层已经导致低噪声（/ SPL Beta /// SPL Alpha / = k> 0.25），以及高达180GHz的增益带宽。这些谐振腔SAM APD的外部量子效率约为80％，导致记录带宽效率产品。击穿电压（v / sub b /）> 15v，暗电流> 10na为90％v / sub b /。
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