Mitsubishi Electric Develops First Monolithically Integrated Laser Diode For 43Gbps
The diode which is suitable for 43Gbps RZ-DQPSK transmission has an InP-based modulator which effectively minimises device size and power consumption.
Mitsubishi Electric Corporation says it has developed the world's first fully monolithically integrated laser diode for use in transmission devices that transmits large date volumes between metropolitan areas.
Operating at 43 giga-bits per second (Gbps), it uses a method called Return to Zero Differential Quadrature Phase Shift Keying (RZ-DQPSK).
Consisting of a tunable laser array, an RZ Mach-Zehnder modulator and a DQPSK Mach-Zehnder modulator, this new laser diode achieves tuning control over the range of 95channels at 40nm in standard set by the 50-GHz International Telecommunication Union Telecommunication Standardization Sector (ITU-T).
This breakthrough will be presented at the Optical Fibre Communication Conference 2011 (OFC 2011) scheduled to be held at the Los Angeles Convention Centre in Los Angeles, CA on March 6 to 10, 2011.
The monolithically integrated single chip consists of a tunable laser array, a Mach-Zehnder intensity modulator and a Mach-Zehnder phase modulator. Mitsubishi Electric claims the three functional chips are monolithically integrated into one and is an industry first.
The tunable laser array wavelength can be controlled between 1572 nm and 1612 nm. The RZ Mach-Zehnder modulator modulates the intensity of output power and the DQPSK Mach-Zehnder modulator modulates the signal phase.
The chip's dimensions are 9.6 x 0.75mm, less than one hundredth of the size of conventional chips. The module's volume, including the chip, can be minimised to less than one third of the size of conventional modules. The chip covers 95 channels of the 50 GHz ITU-T grid in L-band from 1572nm to 1612nm
In the future, Mitsubishi Electric plans to enhance the performance of high power, low consumption and clear optical waveforms. The company also plans to develop a light source for C-band from 1530 nm to 1570 nm.
Transmission volume over optical communication networks is rapidly increasing. The densely spaced wavelength division multiplexed channels, higher bit rate transmission and multi-level formats such as DQPSK are in demand for long distance transmission. Previously, it was common for transmission device manufacturers to use several different chips such as the LiNbO3 Mach-Zehnder modulators and the tunable lasers.
However, the device size is several centimetres or more in length and requires relatively large driving power. The fully monolithic integration and InP-based modulator effectively minimize device size and power consumption. Mitsubishi Electric developed for the first time a 40G RZ-DQPSK transmitter monolithically integrated with a tunable Distributed Feed-Back (DFB) laser array and Mach-Zehnder modulators.