A new technique to generate a millimeter（mm）-wave carrier of 32.57 GHz（f_（LO）=10.85 GHz） with single sideband modulation（SSB） for radio-over-fiber（RoF） systems is experimentally demonstrated by using stimulated Brillouin scattering（SBS）.The SSB is realized by directly amplifying the ＋3rd sideband of the modulated optical carrier in the process of SBS.The pump wave is provided through a double Brillouin scattering frequency shifting configuration.The use of the same laser source to generate the pump wave ensures the stability of the mm-wave generation system since the relative frequency shift between them can be eliminated.In addition, the mm-wave carrier obtains an RF power gain of 21 dB with the SBS amplification and a 3-dB bandwidth of 10kHz.
Monolithic integration of four 1.55-μm-range InGaAsP/InP distributed feedback （DFB） lasers using varied ridge width with a 4 x 1-multimode-interference （MMI） optical combiner and a semiconductor optical amplifier （SOA） is demon- strated. The average output power and the threshold current are 1.8 mW and 35 mA, respectively, when the injection current of the SOA is 100 mA, with a side mode suppression ratio （SMSR） exceeding 40 dB. The four channels have a 1-nm average channel spacing and can operate separately or simultaneously.
The monolithic integration of four 1.55-μm range InGaAsP/InP distributed feedback lasers with a 4× 1 multimode-interference （MMI） optical combiner using the varied width ridge method is proposed and demonstrated. The average output power is 1.5 mW when the current of LD is 100 mA and the threshold current is 30-35 mA at 25 ℃. The lasing wavelength is 1.55-μm range and 40 dB sidemode suppression ratio is obtained. The four channels can operate separately or simultaneously.
The techniques used for the fabrication of photonic integrated circuit(PIC) chip are introduced briefly.Then a four channel DFB laser array integrated with MMI coupler and semiconductor optical amplifier(SOA) fabricated with butt-joint technique,varied ridge width and holographic exposure techniques is reported.
A 1.65μm three-section distributed Bragg reflector （DBR） laser for CH4 gas sensors is reported. The DBR laser has a wide tunable range covering the R3 and R4 methane absorption line manifolds. The wavelength tunability properties, temperature stability and laser linewidth are characterized and analyzed. Several advantages were demonstrated compared with traditional DFB lasers in harmonic detection.
Selective area growth （SAG） is performed to fabricate monolithically integrated distributed feedback （DFB） laser array by adjusting the width of a SiO2 mask. A strain-compensated-barrier structure is adopted to reduce the accumulated strain and improve the quality of multi-quantum well materials. Varying the strip width of the SAG masks, the DFB laser array with an average channel spacing of 1.47 nm is demonstrated by a conventional holographic method with constant-pitch grating. The threshold current from 14 to 18 mA and over 35-dB side mode suppression ratio （SMSR） are obtained for all DFB lasers in the array.
A selected area growth wavelength converter based on a PD-EAM optical logic gate for WDM application is presented, integrating an EML transmitter and a SOA-PD receiver. The design, fabrication, and DC characters were analyzed. A 2 Gb/s NRZ signal based on the C-band wavelength converted to 1555 nm with the highest extinction ratio of 7 dB was achieved and wavelength converted eye diagrams with eyes opened were presented.
