Optical emission spectroscopy of the plasma during sputter deposition of YBCO films for microwave applications

YBCO thin films are currently used in several HTS-based electronics applications. The performance of devices, which may include microwave passive components (filters, resonators), grain boundary junctions or spintronic multilayer structures, is determined by film quality, which in turn depends on the deposition technology used and growth parameters. We report on results from nonintrusive Optical Emission Spectroscopy of the plasma during YBCO thin film deposition in a high-pressure on-axis sputtering system under different conditions, including small trace gas additions to the sputtering gas. We correlate these results with the compositional and structural changes which affect the DC and microwave properties of YBCO films. Film morphology, composition, structure and in- and out-of-plane orientation were assessed; T, and microwave surface resistance measurements were made using inductive and resonator techniques. Comparison was made with films sputtered in an off-axis 2-opposing magnetron system.

Hybrid and passive mode-locking of a monolithic two-section MQW InGaN/GaN laser diode

We report the first hybrid mode-locking of a monolithic two-section multiple quantum well InGaN based laser diode. This device, with a length of 1.5 mm, has a 50-μm-long absorber section located at the back facet and generates a continuous stable 28.6 GHz pulse train with an average output power of 9.4 mW at an emission wavelength of 422 nm. Under hybrid mode-locking, the pulse width reduces to 4 ps, the peak power increases to 72 mW, and the microwave linewidth reduces by 13 dB to <500 kHz. We also observe the passive mode-locking with pulse width and peak power of 8 ps and 37 mW, respectively. © 1989-2012 IEEE.

Athermal colourless C-band optical transmitter for passive optical networks

A new control algorithm with reduced mode-hopping is demonstrated for uncooled WDM C-band channel generation from a DS-DBR laser with 100GHz spacing and low thermal drift up to 70°C. 10Gb/s external modulation with transmission over a 25km link is achieved. ©2010 IEEE.