Park Sungbong, Yamada Koji, Tsuchizawa Tai, Watanabe Toshifumi, Nishi Hidetaka, Shinojima Hiroyuki, Itabashi Sei-ichi
NTT Microsystem Integration Laboratories, NTT Corporation,3-1 Morinosato Wakamiya, Atsugi, Kanagawa 243-0198, Japan.
Opt Express. 2010 Jul 19;18(15):15303-10. doi: 10.1364/OE.18.015303.
We demonstrate a monolithic integration of variable optical attenuators (VOAs) and photodetectors (PDs) based on submicrometer silicon (Si) rib waveguide with p-i-n diode structure for near infrared (NIR) light. To make the Si PD absorptive for NIR, we introduced lattice defects at the rib core by means of argon ion implantation. At reverse bias of 5 V, the PD exhibits dark current of approximately 1 nA, responsivity of approximately 65 mA/W at 1560-nm wavelength, and a 3-dB cut-off frequency of approximately 350 MHz, while the VOA shows approximately 100 MHz. The PD has an absorption coefficient as low as approximately 0.5 cm(-1), which is favorable for an in in-line PD configuration, where the PD absorbs a small portion of the optical power. For DC light, the PD precisely detects the optical power attenuated by the VOA with a detection range of over 40 dB. The 3-dB cut-off frequency of synchronous operation between the VOA and PD is approximately 50 MHz, which is limited by RF noise originating from the VOA drive current. Putting an isolation groove between the VOA and PD is effective for avoiding performance degradation in DC and RF operation.
我们展示了一种基于具有 p-i-n 二极管结构的亚微米硅（Si）肋形波导的可变光衰减器（VOA）和光电探测器（PD）的单片集成，用于近红外（NIR）光。为了使 Si PD 对 NIR 具有吸收性，我们通过氩离子注入在肋形纤芯处引入晶格缺陷。在 5 V 的反向偏置下，该 PD 表现出约 1 nA 的暗电流、在 1560 nm 波长处约 65 mA/W 的响应度以及约 350 MHz 的 3 dB 截止频率，而 VOA 显示约为 100 MHz。该 PD 的吸收系数低至约 0.5 cm⁻¹，这对于在线 PD 配置是有利的，在该配置中 PD 吸收一小部分光功率。对于直流光，该 PD 精确检测由 VOA 衰减的光功率，检测范围超过 40 dB。VOA 和 PD 之间同步操作的 3 dB 截止频率约为 50 MHz，这受到源自 VOA 驱动电流的射频噪声的限制。在 VOA 和 PD 之间设置隔离槽对于避免直流和射频操作中的性能下降是有效的。
