Fast tunable lasers with switching time less than one microsecond are key components in high-speed optical switching networks. In this paper, we propose an effective method to achieve high wavelength switching speed by turning on/off individual lasers of a matrix-grating DFB laser array. The laser array consists of 16 DFB lasers, which are arranged as a 4-by-4 matrix. Besides, the REC technique is used to simplify the fabrication of the grating and precisely control the grating phase. 16 channels with 2.4-nm-spacing are obtained and the SMSRs of all the 16 channels are above 40 dB, indicating good single mode operation. A high-speed driving circuit is designed to supply stable direct current for the DFB laser array and to control the switching process. The experimental result shows that the switching time between 2 channels is less than 100 nanoseconds.
We propose and fabricate a rapidly wavelength switching DFB laser array based on Reconstructed-Equivalent-Chirp technique. A Semiconductor Optical Amplifier(SOA) is applied to enhance and balance the output optical power. The module covers 8 channels from 1554.5nm to 1566.1nm with an interval of 1.6nm. To tune the wavelength on the microsecond scale, we adopt a combination of a MCU and a FPGA as the controlling core to turn on and off the driving current of 8 lasers on the DFB laser array through a collector feedback circuit, and the switching time between 2 channels is well controlled within 300ns. The side mode suppression ratios(SMSRs) of all channels are above 50dB and the output power are guaranteed above 10dBm with the SOA providing 14dBm saturation output power.
A wavelength-tunable small form-factor pluggable (SFP) optical module is proposed and implemented, which is based on a self-designed 4-channel DFB laser array. The module adopts the widely used SFP packaging standard so that it is convenient to connect with other devices. It has an I2C interface for receiving wavelength tuning commands and downloading digital diagnostics monitoring information to the host processor. Three parts are included: the receiver, the transmitter and the microcontroller unit, to complete the conversion of optical-electro, electro-optical. A large range and high precision wavelength tuning is realized through innovative tuning methods. Two wavelength tuning methods are utilized: channel switching of 4-channel for coarse tuning and temperature tuning combined with current tuning for fine tuning to actualize the tunable output of the DFB laser array. This wavelength-tunable SFP optical module can replace several fixed wavelength optical modules in a traditional WDM system, thus greatly reducing costs and improving the utilization ratio of resources. Experimental results show the SFP optical module can achieve the continuity of wavelength tuning covering 1539.0 nm to 1551.0 nm. It can switch over 16 channels in a 100G-DWDM system or 31 channels in a 50G-DWDM system. The side mode suppression ratios (SMSRs) of most channels are above 40dB over the wavelength tuning range of 12 nm. The optical signal transmission rate is up to 1.25Gbps.