The dual parallel Mach-Zehnder (DPMZ) modulator is ideally suited for use in metro, long-haul (LH) and ultra long-haul (ULH) optical transport applications. It is used for spectrally efficient multisymbol transmission based on differential quadrature phase shift keying (DQPSK) modulation. The DPMZ modulator is comprised of two matched, high-speed Mach-Zehnder (MZ) modulators that are monolithically integrated, in parallel, inside an MZ superstructure. The MZ superstructure also functions as a phase (shifter) modulator. DPMZ modulators are specifically designed to yield well-behaved and matching electro-optic amplitude and phase responses over a 20 GHz frequency range and to have enhanced extinction ratios. The DPMZ is available with either singlemode or polarization maintaining output fiber. For mounting convenience and space efficiency, the modulator is designed with the electrical I/O located on one side of the package. The two RF inputs use GPO connectors. DPMZ modulators are packaged using our compact (6-mm high) hermetic packaging technology. The JDSU family of agile optical components includes modulators, switches, attenuators, and tunable filters. These products provide the basis for spectrally efficient DWDM transmission using dispersion-tolerant modulation. They support a broad range of flexible functionalities at lower operating costs for agile optical network. DPMZ modulators have a wide optical bandwidth, and are compatible with full band tunable lasers in either C or L band.