Lu Guo

Widely Tunable Narrow-Linewidth Lasers Using Self-Injection DBR Lasers

A widely tunable distributed Bragg reflector (DBR) laser with kilohertz linewidth output is demonstrated using a dual-loop self-injection scheme. The self-injection-locked narrow linewidth DBR laser can be tuned by 13 nm, covering 18 channels, with side mode suppression ratios over 38 dB and linewidths all <;10 kHz.

Widely tunable monolithic dual-mode laser for W-band photonic millimeter-wave generation and all-optical clock recovery

We demonstrate a monolithic dual-mode amplified feedback laser for photonic millimeter-wave generation and all-optical clock recovery. Dual-mode lasing with beating frequency around 100 GHz was realized by using a single-mode distributed feedback (DFB) laser with a short feedback cavity that was integrated by simple quantum-well intermixing technology. By tuning the bias currents of the laser sections, the beating-frequency can be continuously tuned from 75 to 109 GHz, almost covering the entire W-band (75-110 GHz). Furthermore, by using this device, an all-optical clock recovery for 100 Gbit/s return-to-zero on-off-keying signal was achieved with a timing jitter of 301 fs.

640-Gbit/s fast physical random number generation using a broadband chaotic semiconductor laser

An ultra-fast physical random number generator is demonstrated utilizing a photonic integrated device based broadband chaotic source with a simple post data processing method. The compact chaotic source is implemented by using a monolithic integrated dual-mode amplified feedback laser (AFL) with self-injection, where a robust chaotic signal with RF frequency coverage of above 50 GHz and flatness of ±3.6 dB is generated. By using 4-least significant bits (LSBs) retaining from the 8-bit digitization of the chaotic waveform, random sequences with a bit-rate up to 640 Gbit/s (160 GS/s × 4 bits) are realized. The generated random bits have passed each of the fifteen NIST statistics tests (NIST SP800-22), indicating its randomness for practical applications.

A Dual-Grating InGaAsP/InP DFB Laser Integrated With an SOA for THz Generation

We report a dual-mode semiconductor laser that has two gratings with different periods below and above the active layer. A semiconductor optical amplifier (SOA), which is integrated with the dual-mode laser, plays an important role in balancing the optical power and reducing the linewidths of the emission modes. A stable two mode emission with the 13.92-nm spacing can be obtained over a wide range of distributed feedback and SOA injection currents. Compared with other types of dual-mode lasers, our device has the advantages of simple structure, compact size, and low fabrication cost.

Low chirp electroabsorption-modulated DFB laser fabricated by combining selective-area growth and double-stack active layer techniques

We present a low chirp electroabsorption modulator integrated DFB laser (EML) fabricated by a selective area growth double stack active layer technique. A stable single mode operation can be obtained and the typical side mode suppression ratio (SMSR) is over 53 dB. The threshold current of the device is about 16 mA and the optical output power from the EAM fact is over 8 mW at an injection current of 80 mA. A static extinction ratio as high as 34 dB can be obtained when the bias voltage is approaching -5 V. The chirp parameters of the EML chip are measured with a fiber resonance method. Negative chirp parameters can be obtained when the reverse bias voltage increases to 1 V. A clear 25 Gb/s back to back eye diagram can be achieved and a 20 Gb/s eye diagram can be seen after the transmission of 25 km single mode fiber. The EAM can operate at 20 Gb/s with a dynamic extinction of 8.6 dB with a driving voltage as low as 0.65 V. The fabricated EML chip shows great advantages in very-short-reach systems as well as long distance applications.

Electrically and Optically Bistable Operation in an Integration of a 1310nm DFB Laser and a Tunneling Diode

We experimentally demonstrate an InP-based hybrid integration of a single-mode DFB laser emitting at around 1310nm and a tunneling diode. The evident negative differential resistance regions are obtained in both electrical and optical output characteristics. The electrical and optical bistabilities controlled by the voltage through the tunneling diode are also measured. When the voltage changes between 1.46V and 1.66 V, a 200-mV-wide hysteresis loop and an optical power ON/OFF ratio of 17 dB are obtained. A side-mode suppression ratio of the integrated device in the ON state is up to 43 dB. The tunneling diode can switch on/off the laser within a very small voltage range compared with that directly controlled by a voltage source.

1.3-μm dual-wavelength DFB laser chip with modulation bandwidth enhancement by integrated passive optical feedback.

We report a 1.3-μm dual-wavelength distributed feedback (DFB) photonic integrated chip with modulation bandwidth enhancement using integrated optical feedback section. The dual-wavelength DFB lasers were realized using the upper separate confinement heterostructure (SCH) selective area growth (SAG) approach. A modified butt-joint technique was also adopted to achieve high-quality active-passive interface and minimize unintentional intra-cavity optical feedbacks. The fabricated photonic chip exhibited stable single mode operations with a wavelength separation of 2.06 nm. The 3-dB modulation bandwidth was enhanced through the photon-photon resonance effect with f3dB > 17 GHz and open eyes up to 25 Gbit/s for both channels were also obtained. The design can also be scaled up to higher channel counts and higher data rate.

Photonic Generation of Linearly Chirped Microwave Waveform Using a Distributed Bragg Reflector Laser

A linearly chirped microwave waveform with a pulse duration of

Modulated bandwidth enhancement in an amplified feedback laser

1-\mu \mathrm{s}

100 Gb/s all-optical clock recovery based on a monolithic dual-mode DBR laser

, bandwidth of 17.5-GHz and time-bandwidth product of