500-Gb/s/λ Operation of Ultra-Low Power and Low-Temperature-Dependence InP-Based High-Bandwidth Coherent Driver Modulator

Abstract

For 64-Gbaud operation and beyond, we developed a power efficient high-bandwidth coherent driver modulator composed of a linear four-channel ultra-low power CMOS driver IC and an InP-based dual-polarization IQ modulator. The CMOS driver was fabricated in 65-nm CMOS technology and showed power dissipation of <1 W owing to the use of an open-drain configuration and a stacked current-mode architecture. Moreover, by optimizing the temperature of the thermoelectric cooler that controls the modulator operating temperature, the coherent driver modulator achieved consumed power of <2.5 W at case temperatures of −5 to 75°C and <2.8 W under −5 to 85°C. As far as we know, this is the lowest power dissipation for a coherent driver modulator with an InP modulator chip. In addition, by employing a circuit that suppresses temperature dependence of RF characteristics in the CMOS driver, we achieved the 3-dB electro-optical bandwidth of >44 GHz and the variation of 2.0 GHz under the 25°to 85°C condition. Furthermore, we obtained good back-to-back bit-error-rate performance in up to dual polarization 80-Gbaud 16-QAM modulation.

Hitless Wavelength Switching of Semiconductor Optical Amplifier-integrated Reflection-type Transversal Filter Laser with Suppressed Frequency Error

“…So, a semiconductor optical amplifier (SOA) is an ideal optical shutter because the ACT of a laser cavity does not have to be dynamically turned off/on. Furthermore, unlike an electro-absorption (EA) modulator [14,15] and a Mach-Zehnder (MZ) modulator [16][17][18], it is possible to obtain a high extinction ratio (ER) without wavelength-dependent bias control proven in the form of SOA gate switches [19][20]. A residual issue in using an SOA as an optical shutter is thermal crosstalk from the SOA to the laser cavity, which results in a laser frequency drift [21][22][23][24][25].…”

Over-85-GHz-Bandwidth InP-Based Coherent Driver Modulator Capable of 1-Tb/s/λ-Class Operation

“…as a coherent driver modulator (CDM) [4][5][6] and an intradyne coherent receiver (ICR) [6][7][8], are key components for highspeed multi-level operation. These components integrate optical and electrical devices in one package to reduce the RF loss, footprint and cost.…”

“…InP modulator chips have been commonly used for CDMs [5,6] because they can achieve high bandwidth with a low driving voltage and a small footprint [9,10]. Recently, novel CDM using a thin-film LiNbO3 (TFLN) modulator was demonstrated [11].…”

Coherent Driver Modulator With Flexible Printed Circuit RF Interface for 128-Gbaud Operations

“…Regarding optical IQ modulator chips that are assembled in the HB-CDM, InP-based IQ modulators have been used for their superior material properties that enable them to achieve high speeds and low driving voltages with a small footprint [4,5]. An InP IQ modulator with 3-dB electro-optic (EO) bandwidth of 80 GHz and half-wave voltage (Vπ) of 1.5 V has J. Ozaki, Y. Ogiso, Y. Hashizume, and M. Ishikawa are with NTT Device Innovation Center, Nippon Telegraph and Telephone Corporation, Atsugi, Kanagawa 243-0198, Japan (e-mail: josuke.ozaki.mp@hco.ntt.co.jp; yoshihiro.ogiso.uv@hco.ntt.co.jp; yasuaki.hashizume.ph@hco.ntt.co.jp; mitsuteru.ishikawa.pe@hco.ntt.co.jp).…”