| الوصف: |
Several groups have reported the properties of experimental photonic switches based on the matrix-vector multiplier architecture. The shutters in these switches have consisted of a variety of passive materials, such as PLZT, PDLC, and deformable mirror elements. Some switches have been symmetric (same fiber diameter at output and input), some have been asymmetric (larger fiber diameter at output than at input), some have had single-mode inputs, and some have had multimode inputs. The limitations to switch size posed by loss and signal-to-noise considerations for such passive technologies are assessed, including fan-out loss, fan-in loss, and other excess loss. Semiconductor optical amplifiers offer potential improvement of such switches, through faster switching times, lower losses, higher contrast ratios, and high levels of integration. The limitation to switch size posed by noise, particularly spontaneous emission noise, becomes an important question. The increases in switch size afforded by the use of amplifiers are estimated, taking full account of spontanious emission noise. Semiconductor optical amplifiers have been used to construct a 2 × 2 optical crossbar switch with 3 dB of net gain. The amplifiers were angled stripe, gain guided, superluminescent diodes with antireflection coatings (provided by Sarnoff Laboratories). The net gain (including pigtailing loss) for a single device was at best 7 dB. Extinction ratios of 30 dB were merasured and switching times were a few nanoseconds. Assembly of the 2×2 switch yielded a net gain of 3 dB. |
