Sub‐sampling of RF and THz waves using LT‐GaAs photoconductors under 1550 nm light excitation

Abstract

Low-temperature-grown GaAs (LT-GaAs)-based Fabry-Pérot cavity photoconductors, designed for RF and THz optoelectronics applications using1550 nm lasers, are studied. The sub-sampling of continuous waves at frequencies up to 300 GHz is presented. The duty-cycle-limited conversion losses measured up to 67 GHz show that this GaAs-based photoconductor behaves as a nearly perfect photoswitch controlled by a 1550 nm pulsed laser.

High‐Speed Optoelectronic Graphene Sampler at 1.55 µm Reaching Intrinsic Performances

“…The rapid progress in low-jitter optical clocks [5,6] opened the possibility to perform optoelectronic sampling [7][8][9][10][11][12][13] with ultra-stable optical pulse trains having extremely low phase noise and jitter (generated by active mode-locked lasers). Optoelectronic subsampling of GHz and THz signals has been demonstrated with optical switches made of GaAs-based films grown at low-temperature [14][15][16][17] paving the way for the efficient sampling of high-frequency signals. III-V semiconductor materials such as low temperature grown GaAs operating at either its optimal wavelength of 0.8 μm [15] or at 1.55 μm [16,17] are particularly studied.…”

“…Optoelectronic subsampling of GHz and THz signals has been demonstrated with optical switches made of GaAs-based films grown at low-temperature [14][15][16][17] paving the way for the efficient sampling of high-frequency signals. III-V semiconductor materials such as low temperature grown GaAs operating at either its optimal wavelength of 0.8 μm [15] or at 1.55 μm [16,17] are particularly studied. These studies highlighted that device linearity is crucial to mitigate harmonics generation, which introduces a parasitic signal in the sampling operation.…”

“…Comparison with state-of-the-art optoelectronic samplers based on LT-GaAs. [15,16] 𝜆 opt is the optical wavelength, f cl the clock frequency, T p the pulse width, P RF the RF power, f RF the RF frequency, 𝜏 the carrier lifetime, and P opt the optical power. Measured conversion efficiency (Meas.)…”

Low‐temperature‐grown gallium arsenide photoconductors with subpicosecond carrier lifetime and photoresponse reaching 25 mA/W under 1550 nm CW excitation

“…lower than the energy gap of GaAs ( E g = 1.42 eV), by placing the LT‐GaAs layer inside an optical resonant cavity [7]. This photoconductor has been then successfully used to sub‐sample continuous waves at frequencies up to 300 GHz, demonstrating a sub‐picosecond response time of photocurrents generated by 1550 nm illumination [8]. However, the much higher dark resistivity of LT‐GaAs material (>10 3 kΩ cm) in comparison with LT‐InGaAs/InAlAs multilayers material [9] or Fe‐doped InGaAs layers [10] (<2 kΩ cm) employed in 1550‐nm ultrafast photoconductors is far from compensating the low photoresponse despite the use of an optical cavity (≈ 1 mA/W under CW illumination [7]).…”

InAlAs/InGaAs-MSM photodetectors based on optical cavity using metallic mirrors: THz frequency operation, high quantum efficiency and high saturation current

“…The superior properties of the nanostructured semitransparent top mirror in terms of optical losses at 1550 nm and low parasitic serial resistance has been already demonstrated in previous works. 2,24 The semiconductor stack, grown by molecular beam epitaxy, consists of an In0.53Ga0.47As absorption layer of thickness tInGaAs surrounded by two graded In0.52Al0.48As / In0.53Ga0.47As multilayers (total thickness tInAlGaAs) followed by two In0.52Al0.48As (thickness tInAlAs) layers [see Fig. 1(c) and Fig.…”