Continuous-wave 6-dB-squeezed light with 2.5-THz-bandwidth from single-mode PPLN waveguide - Kashiwazaki, Takahiro; Takanashi, Naoto; Yamashima, Taichi; Kazama, Takushi; Enbutsu, Koji; Kasahara, Ryoichi; Umeki, Takeshi; Furusawa, Akira (APL photonics, 2020)