Infinera asserts it has reached a pair of optical transmission milestones. The company says it has been able to leverage 100 GBaud modulation to deliver a 1-Tbps transmission rate. It also says it has achieved 1024QAM transmission. Infinera reported both results at ECOC 2017 in Gothenburg, Sweden last month.The company asserts the 100-GBaud transmission is an industry first. Company researchers used 32QAM via multi-channel indium phosphide-based photonic integrated circuits (PICs) integrated with electronic driver and amplifier ASICs to achieve the single-wavelength 1-Tbps transmission. As a point of comparison, most current coherent transmissions use 32 GBaud, with research underway at many companies on greater than 60 GBaud (see, for example, "NeoPhotonics offers 64-GBaud coherent line for 600G and up").The 1024QAM work used what Infinera described as "advanced constellation shaping algorithms" and Nyquist subcarriers. The company has already highlighted its use of Nyquist subcarriers in its Infinite Capacity Engine (see "Infinera moves terabit optical networks closer to commercialization with Infinite Capacity Engine"). In the most recent instance, the test bed used 66 GBaud at 1024QAM to achieve 1.32 Tbps. The transmission featured a spectral efficiency of 9.35 bits per second per hertz over 400 km, which Infinera asserts also is an industry first.