The in-plane anisotropy of transition metal trichalcogenides (MX₃) has a significant impact on the molding of materials and MX₃ is a perfect choice for polarized photodetectors. In this study, the crystal structure, optical and optoelectronic anisotropy of one kind of quasi-one-dimensional (1D) semiconductors, ZrSe₃, are systematically investigated through experiments and theoretical studies. The ZrSe₃-based photodetector shows impressive wide spectral response from ultraviolet (UV) to near infrared (NIR) and exhibits great optoelectrical properties with photoresponsivity of 11.9 mA·W^-1 and detectivity of ~10⁶ at 532 nm. Moreover, the dichroic ratio of ZrSe₃-based polarized photodetector is around 1.1 at 808 nm. This study suggests that ZrSe₃ has potential in optoelectronic applications and polarization detectors.The in-plane anisotropy of transition metal trichalcogenides (MX₃) has a significant impact on the molding of materials and MX₃ is a perfect choice for polarized photodetectors. In this study, the crystal structure, optical and optoelectronic anisotropy of one kind of quasi-one-dimensional (1D) semiconductors, ZrSe₃, are systematically investigated through experiments and theoretical studies. The ZrSe₃-based photodetector shows impressive wide spectral response from ultraviolet (UV) to near infrared (NIR) and exhibits great optoelectrical properties with photoresponsivity of 11.9 mA·W^-1 and detectivity of ~10⁶ at 532 nm. Moreover, the dichroic ratio of ZrSe₃-based polarized photodetector is around 1.1 at 808 nm. This study suggests that ZrSe₃ has potential in optoelectronic applications and polarization detectors.

We demonstrate a package-level passive equalization technology in which the wire-bonding-induced resonance effect is used to compensate for the limited gain strength within the Nyquist frequency. The corresponding gain strength under various inductance and capacitance combinations could be quantitatively determined using a numerical simulation. With the increase in the Nyquist frequency, the capacitance shows a greater effect on the gain strength than the inductance. Therefore, the parasitic capacitance should be decreased to realize the desired gain strength at a higher Nyquist frequency. With this equalization technology, gain strength of 5.8 dB is obtained at 22 GHz, which can compensate for the limited bandwidth for the 112 Gbps pulse amplitude modulation (PAM4) signal. The experimental results show that 112 Gbps/λ PAM4 transmission based on a directly modulated laser (DML) module can be realized with a bit error rate of 1 × 10 ³ at a received optical power of 3 dBm.

An ultra-compact hybrid-integration receiver optical subassembly (ROSA) with four channels is demonstrated in our laboratory with the size of 23.3 mm × 6.0 mm × 6.5 mm. The ROSA is comprised of a planar lightwave circuit (PLC) arrayed waveguide grating (AWG) chip, a top-illuminated positive-intrinsic-negative photodetector array chip, and a three-dimensional microwave circuit that is specially designed for compact packaging. For each transmission lane, the 3 dB bandwidth of the ROSA is up to 20 GHz, and the maximum responsivity is up to 0.53 A/W. The proposed package structure can be used for smaller package sizes and would be an easy assembling solution for 100 GbE optical communication devices.

Based on the hybrid integration technology, an ultra-compact and low cost transmitter optical subassembly module is proposed. Four directly modulated lasers are combined with a coarse wavelength division multiplexer operated at the O-band. The bandwidth for all channels is measured to be approximately 3 GHz. The 112 Gb/s transmission is experimentally demonstrated for a 10 km standard single mode fiber (SSMF), in which an optical isolator is used for avoiding the back-reflected and scattered light to improve the bit error rate (BER) performance. A low BER and clear eye opening are achieved for 10 km transmission.

Compact transmitter and receiver optical sub-assemblies (TOSA and ROSA) are fabricated in our laboratory and have an aggregated capacity of 100 Gb/s. Specially, directly modulated laser (DML) drivers with two layers of electrical circuit boards are designed to inject RF signals and bias currents separately. For all the lanes, the 3 dB bandwidth of the cascade of the TOSA and ROSA exceeds 9 GHz, which allows the 12.5 Gb/s operation. With the 12.5 Gb/s × 8-lane operation, clear eye diagrams for back-to-back and 30-km amplified transmission with a dispersion compensation fiber are achieved. Low cost and simple processing technology make it possible to realize commercial production.