Hsiu-Po Chuang

Remotely Up-Converted 20-Gbit/s Error-Free Wireless On–Off-Keying Data Transmission at W-Band Using an Ultra-Wideband Photonic Transmitter-Mixer

We demonstrate a remotely up-converted and distributed 20-Gbit/s wireless on-off-keying (OOK) data transmission link at the W-band that uses a near-ballistic uni-traveling-carrier photodiode (NBUTC-PD)-based photonic transmitter-mixer. This device consists of an active NBUTC-PD integrated with a planar passive circuit for feeding the intermediate-frequency (IF) modulation input and extracting the up-converted optical-to-electrical (O-E) output signals. An equivalent-circuit model is developed, which allows for the O-E and IF responses to be independently optimized. Accordingly, we can achieve both an ultra-wide O-E bandwidth (67-118 GHz) and IF modulation bandwidth (>;15 GHz) with a very-low coupling loss (<; 2 dB) from the NBUTC-PD to the WR-10 waveguide. We adopted a remotely distributed 1-ps optical pulse train source with a repetition rate at 93 GHz to serve as a high-performance photonic carrier, which is generated by a spectral line-by-line shaper utilizing the repetition-rate multiplication (RRM) technique. In contrast to lossy amplitude filtering, our RRM is based on applying periodic loss-less spectral phase filtering onto the 31-GHz comb lines. In comparison with the conventional 93-GHz sinusoidal carrier, the photogenerated millimeter-wave (MMW) power of this kind of carrier is 4 dB higher than that of PD under the same output photocurrent. In contrast to the traditional mode-locked laser, the fiber dispersion can be totally precompensated without additional dispersion compensation components. By use of such device and optical MMW source, we successfully demonstrate remotely distributed and up-converted 20-Gbit/s error-free OOK wireless data transmission link over a 25-km standard single-mode fiber.

Spectral Power Enhancement in a 100 GHz Photonic Millimeter-Wave Generator Enabled by Spectral Line-by-Line Pulse Shaping

We report generation of high-modulation-depth photonic millimeter-wave (MMW) waveforms by applying line-by-line pulse shaping on a phase-modulated continuous-wave frequency comb. The optimized 20 and 100 GHz optical waveforms are then converted into electrical MMW signals using a near-ballistic uni-traveling-carrier photodiode (NBUTC-PD). A 7.4 dB MMW power enhancement is experimentally achieved by using 2.6 ps optimized pulses at a 100 GHz repetition rate, as compared with excitation by a conventional sinusoidal signal for the NBUTC-PD operated at the same photocurrent. This is in qualitative agreement with a theoretical analysis of spectral power enhancement by optical short pulses comprised of equi-amplitude frequency lines over sinusoidal excitation.

Generation and delivery of 1-ps optical pulses with ultrahigh repetition-rates over 25-km single mode fiber by a spectral line-by-line pulse shaper

A spectral line-by-line pulse shaper is used to experimentally generate and deliver ~1 ps optical pulses of 31~124 GHz repetition-rates over 25.33 km single-mode fiber without dispersion-compensating fiber. The correlation of such delivery capability to temporal Talbot effect is experimentally demonstrated. Incorporating shaper periodic phase control, the repetition-rates of these~1 ps optical pulses are further multiplied up to 496 GHz and delivered over 25.33 km single-mode fiber.

Forty-photon-per-pulse spectral phase retrieval by shaper-assisted modified interferometric field autocorrelation

We report on spectral phase retrieval of 400 fs pulses using shaper-assisted modified interferometric field autocorrelation. The coupled energy is only 5.2 aJ per pulse, corresponding to an unprecedented sensitivity of 2.7 × 10⁻⁹ mW².

Photonic Generation and Detection of W-Band Chirped Millimeter-Wave Pulses for Radar

Based on the frequency-to-time mapping approach, we generate frequency-modulated millimeter-wave (MMW) pulses with central frequencies up to the W-band by a shaped optical pulse excitation of an MMW photonic transmitter with an ultrawide band photodiode as its key component. A coherent detection is achieved via a terahertz time-domain spectroscopic setup. Two different kinds of chirped MMW waveforms are generated; one is a linearly chirped sinusoidal pulse and the other is produced by a frequency-stepped modulation. Through appropriate optical spectral design, the frequency-chirped MMW pulses with instantaneous frequencies sweeping from 120 to 60 GHz, and a time-bandwidth product of ~ 25 is experimentally demonstrated.

20-Gb/s error-free wireless transmission using ultra-wideband photonic transmitter-mixer excited with remote distributed optical pulse train

Photonic transmitter-mixers with ultra-wide O-E/modulation bandwidths excited by remote-distributed pulse trains for 20Gbps error-free wireless transmission is presented. The S/N ratios and output power are greater than sinusoidal excitation.

Enhanced Performance of Narrowband Millimeter-Wave Generation Using Shaped-Pulse-Excited Photonic Transmitters

We demonstrate a novel method to greatly enhance the narrowband millimeter-wave (MMW) power generation by use of a near-ballistic uni-traveling-carrier photodiode-based photonic transmitter (PT) excited by shaped optical pulses. The spectrum of the best tailored optical pulses is centered at 1545 nm and spread among 16 main frequency components (channels), each with a spectral width of 15.5 GHz and a spacing of 93 GHz. Compared with quasi-sinusoidal optical modulation, we achieve an enhancement in the spectral power density by ~25 times. The power-enhanced narrowband MMW signal can be tuned over ~80 GHz (60-142 GHz). In addition, we observe significant enhancement of MMW peak power with an increase of the reverse bias voltage.

20-Gb/s on-off-keying wireless data transmission by using bias modulation of NBUTC-PD based w-band photonic transmitter-mixer

We demonstrated near-ballistic uni-traveling-carrier photodiode based broadband photonic transmitter-mixers with quasi-Yagi radiators fed horn antennas. By adopting a novel design in the intermediate-frequency (IF) port of such device, we can further extend the IF (bias) modulation bandwidth of NBUTC-PD to over 14GHz. Wireless data transmission with record-high on-off keying date rate as 20-Gb/s via bias modulation of such novel device has been successfully achieved.

Adiabatic soliton spectral compression in a dispersion-increasing fiber

For the first time to our best knowledge, adiabatic soliton spectral compression is experimentally demonstrated in a dispersion-increasing fiber. Spectral compression ratio of 15.5 is obtained using 350 fs up-chirped pulse in the 1.5 μm.

Power-enhanced narrow-band Sub-THz generation by use of a photonic transmitter and shaped optical pulses

By using optimized shaped optical pulses, we demonstrate a factor-of-~25 enhancement in the spectral power density of sub-THz wave at 93 GHz compared with that for quasi-sinusoidal optical modulation.