Efficient terahertz emission from ballistic transport enhanced n-i-p-n-i-p superlattice photomixers

Abstract

The authors report on photomixing terahertz sources that overcome the transit time versus RC-time trade-off and allow for independent optimization of both of them, using a n-i-p-n-i-p superlattice. Furthermore, they take advantage of ballistic transport for reduced transit times. Apart from more favorable material parameters, In(Al)GaAs photomixers benefit from the advanced telecommunication laser technology around 1.55 mu m as compared to GaAs. In such devices, a terahertz-power output of 1 mu W has been achieved at 0.4 THz at a photocurrent of 3.8 mA. A comparison between corresponding GaAs- and InGaAs-based n-i-p-n-i-p photomixers reveals an improvement of performance by at least an order of magnitude for the latter one. (c) 2007 American Institute of Physics

Tunable, continuous-wave Terahertz photomixer sources and applications

“…Under ballistic transport conditions, the THz power is very sensitive to the external voltage 110 for frequencies higher than the 3 dB frequency obtained by transport with the saturation drift velocity of electrons. The optimum bias point of the emitter is determined by measuring the THz power versus applied voltage.…”

Comparison of Monolithic Optical Frequency Comb Generators Based on Passively Mode-Locked Lasers for Continuous Wave mm-Wave and Sub-THz Generation

“…The photodiode used in this experiment has a maximum optical input power of 20 mW and a 3-dB bandwidth of 50 GHz and it is clearly limiting the performance above 90 GHz regardless the high bandwidth available associated to our OFCGs. However, as previously mentioned, state of the art photomixers can reach values up to 1 THz in the case of Uni-Travelling-Carrier Photodiodes (UTC-PD) [18], Travelling-Wave Uni-Travelling-Carrier Photodiodes (TW-UTC-PD) [19] or n-i-pn-i-p superlattice photomixers [20]. Hence, the proposed scheme can be readily scaled to synthesize higher frequencies.…”

“…This electrical frequency must be within the bandwidth of the photomixer to properly achieve generation (highest output power). Suitable photomixer devices include photoconductive antennas (PCAs) [15], uni-travelling-carrier photodiodes (UTC-PDs) [18], travelling-wave uni-travelling-carrier photodiodes (TW-UTC-PDs) [19] or n-i-pn-i-p superlattice photomixers [20]. The two optical frequencies can be provided by two different sources (lasers) or by a single optical source.…”

“…8. Signals up to 814 GHz (Maximum optical FWHM of Device A in Table I) and up to 1229 GHz (Maximum optical FWHM of Device B in Table I) can be synthesized provided a sufficient bandwidth photomixer [18]- [20].…”

Continuous-Wave Sub-THz Photonic Generation With Ultra-Narrow Linewidth, Ultra-High Resolution, Full Frequency Range Coverage and High Long-Term Frequency Stability

“…Devices based on p-i-n structures are preferred to photoconductors due to their higher available output power, although they offer a lower bandwidth, around 1.53 THz [23]. Examples of these p-i-n devices are Uni-Travelling-Carrier photodiodes (UTC-PD) [31], Travelling-Wave UniTravelling-Carrier (TW-UTC-PD) [23] and n-i-pn-i-p superlattice photomixers [30], [34], [35]. The latter take advantage of a superlattice of p-i-n diodes allowing for independent optimization of both transit and RC times, thus overcoming the trade-off usually present in most highbandwidth photodiodes.…”