Chen-Bin Huang

Spectral line-by-line pulse shaping

In this paper, we review spectral line-by-line pulse shaping, including examples of waveform generation, data demonstrating sensitivity to comb offset frequency, and requirements for high fidelity waveform generation. In order to achieve spectral line-by-line pulse shaping, we have improved the spectral resolution of grating-based pulse shapers to ~2.5 GHz, and performed experiments utilizing high repetition rate (~10 GHz) pulse sources, including harmonically mode-locked fiber lasers and strongly phase modulated CW lasers.

Nonlinearly broadened phase-modulated continuous-wave laser frequency combs characterized using DPSK decoding

9.953 GHz phase-modulated continuous-wave laser combs are spectrally broadened via nonlinear propagation in normal and anomalous dispersion media and experimentally characterized using a differential phase shift keying (DPSK) decoder. DPSK bit-error rate data are in qualitative agreement with radio-frequency spectrum analyzer measurements.

Time-multiplexed photonically enabled radio-frequency arbitrary waveform generation with 100 ps transitions

For the first time, to our knowledge, radio-frequency arbitrary waveforms are time-multiplexed within 100 ps by integrating wavelength switching, optical frequency comb generation, and spectral line-by-line shaping. The novel time-multiplexed scheme demonstrated here can be extended to wide user specifications and faster waveform transition time.

Spectral Line-by-Line Pulse Shaping on an Optical Frequency Comb Generator

We demonstrate optical processing based on spectral line-by-line pulse shaping of a frequency comb generated by an optical frequency comb generator (OFCG). The OFCG is able to generate a smooth, broad, stable, known-phase frequency comb, which is ideal for recently developed spectral line-by-line pulse shaping technology applications. We demonstrate line-by-line pulse shaping on 64 lines at 10-GHz line spacing, generate transform-limited 1.6-ps short pulses at 10 GHz by combining two pulses in each period directly from the OFCG, and show various examples for optical arbitrary waveform generation. Further, we demonstrate that these pulse sources are of sufficient quality to support optical fiber communication applications as confirmed by bit error rate measurements.

Femtosecond pulse shaping in two dimensions: Towards higher complexity optical waveforms.

We demonstrate a new Fourier pulse shaping apparatus capable of achieving simultaneous high resolution and broad bandwidth operation by dispersing frequency components in a two dimensional geometry through simultaneous use of a high resolution and a broad bandwidth spectral disperser. We show experimental results which demonstrate significant improvements in achievable waveform complexity (number of controllable temporal/spectral features). We also demonstrate experiments of line-by-line pulse shaping with optical frequency combs. In this regime our configuration would allow significant enhancement of the number of controllable spectral lines which may further enhance recently demonstrated massively parallel approaches to spectroscopic sensing using frequency combs.

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.

Creating Optical Near-Field Orbital Angular Momentum in a Gold Metasurface

Nanocavities inscribed in a gold thin film are optimized and designed to form a metasurface. We demonstrate both numerically and experimentally the creation of surface plasmon (SP) vortex carrying orbital angular momentum in the metasurface under linearly polarized optical excitation that carries no optical angular momentum. Moreover, depending on the orientation of the exciting linearly polarized light, we show that the metasurface is capable of providing dynamic switching between SP vortex formation or SP subwavelength focusing. The resulting SP intensities are experimentally measured using a near-field scanning optical microscope and are found in excellent quantitative agreements as compared to the numerical results.

Photonic Generation and Wireless Transmission of Linearly/Nonlinearly Continuously Tunable Chirped Millimeter-Wave Waveforms With High Time-Bandwidth Product at W-Band

We demonstrate a novel scheme for photonic generation of chirped millimeter-wave (MMW) pulse with ultrahigh time-bandwidth product (TBP). By using a fast wavelength-sweeping laser with a narrow instantaneous linewidth, wideband/high-power photonic transmitter-mixers, and heterodyne-beating technique, continuously tunable chirped MMW waveforms at the W-band are generated and detected through wireless transmission. Compared with the reported optical grating-based wavelength-to-time mapping techniques for chirped pulse generation, our approach eliminates the problem in limited frequency resolution of grating, which seriously limits the continuity, tunability, and TBP of the generated waveform. Furthermore, by changing the alternating current (AC) waveform of the driving signal to the sweeping laser, linearly or nonlinearly continuously chirped MMW pulse can be easily generated and switched. Using our scheme, linearly and nonlinearly chirped pulses with record-high TBPs (89-103 GHz/ 50 μs/7 × 105) are experimentally achieved.

Loss-less pulse intensity repetition-rate multiplication using optical all-pass filtering

Schemes based on an optical all-pass filtering techniques for multiplying the intensity repetition-rate of an optical pulse train are examined. These methods are in principle without energy loss and the multiplication factor can be any given integer. Practical implementation using cascaded side-coupled ring resonators or multireflection filters is proposed and analyzed for the first time.

Dual-comb electric-field cross-correlation technique for optical arbitrary waveform characterization

We present an electric-field cross-correlation technique that uses a pair of frequency combs to sweep phase and group delays independently without a mechanical stage. We demonstrate this technique for characterization of optical arbitrary waveforms composed of ~30 spectral lines from a 10 GHz frequency comb. Rapid data acquisition (tens of microseconds) enables interferometric spectral phase measurement of pulses subject to propagation over 20 km of optical fiber.