D. Wake

Two-terminal edge-coupled InP/InGaAs heterojunction phototransistor optoelectronic mixer

We report the first experimental results for optoelectronic mixing using a two-terminal edge-coupled InP/InGaAs heterojunction phototransistor (HPT). The HPT optoelectronic mixer (OEM) exhibits a maximum of 7-dB conversion gain relative to a 100% quantum efficient photodetector operated at the optical modulation frequency. We give a qualitative explanation for the observed conversion gain variation with the HPT bias voltage.

Microwave frequency synthesis using injection locked laser comb line selection

Microwave frequency synthesis can be realised by mixing the output of two or more DFB lasers injection locked to the same optical comb. The noise and stability problems of this approach are studied.

Multiple-quantum-well asymmetric Fabry-Perot modulators for microwave photonic applications

We describe the development of InGaAsP multiquantum-well asymmetric Fabry-Perot modulators (AFPM) for RF-over-fiber applications. Advantages of the AFPM include low drive voltage and loss, high linearity and simple fiber alignment. Experimental results of initial devices, exhibiting 5.5-dB modulation depth and >3-GHz operation, are described. The effect of the optical power on the device performance was assessed, and the modulation bandwidth was found to be unaffected by incident optical powers up to 0 dBm. The linearity of the modulation characteristic was measured by carrying out two-tone intermodulation distortion tests, and a third-order intercept point of 30 dBm was observed.

Millimetre-wave over fibre transmission using a BPSK reference-modulated optical injection phase-lock loop

We report generation of single sideband millimetre-wave modulated optical signals by a reference-modulated optical injection phase-lock loop. A 36 GHz 68 Mbit/s BPSK signal is transmitted over 25 km of unamplified SMF with 8 dB optical power margin and BER<10/sup -9/.

High-dynamic-range linear analog data links (1-20 GHz) using room temperature DFB laser diodes

We report the analysis and application of uncooled, directly-modulated high-speed DFB lasers with emphasis on their analogue transmission performance. Fibre-optic links employing such lasers are shown to meet the most stringent requirements of analogue systems at both high carrier frequencies and high temperatures. Spurious-free dynamic ranges (SFDR) exceeding 100dB×Hz2/3 and 90dB×Hz2/3 and input third-order intercept points (IIP3) above 20dBm and 18dBm are reported for carrier frequencies up to 20GHz at 25°C and up to 10GHz at 85°C, respectively. The error-vector magnitude (EVM) for a 256-QAM modulated signal transmitted over 15km of SMF remains below 1.9% for carrier frequencies of both 2GHz and 5GHz for all measured temperatures. The link performance is assessed by using 3GPP W-CDMA, IEEE 802.11a and IEEE 802.11b signals. In all cases the EVM remains within the standard specification, for fibre-optic link lengths of up to 10km and laser operating temperatures of up to 70°C. Finally, an IEEE 802.11b WLAN demonstrator is presented, allowing antenna remoting over up to 1000m of 62.5/125μm MMF.

Study of distortion performance of uncooled low cost RF MMF links

We show that multimode fibre links using directly modulated DFB laser diodes exhibit linear RF performance up to 85/spl deg/C. The SFDR performance is better than 80 dB.Hz/sup 2/3/ for both 2 GHz and 5 GHz carriers frequencies.