Study On 1.3μm DFB Semiconductor Laser And Laser Array Based On The Reconstruction-equivalent-chirp Technique

The 21st century is the information age. With the rapid development of internet and wireless communication, the network demand increases explosively. The advent of optical fiber communication makes communication with high speed and large capacity possible and has become the main technology for information transmission. The distributed feedback semiconductor laser (DFB) which has advantages such as small volumn, high efficience and light weight is the main light source of optical fiber communication. With further increase of the capacity of the optical fiber communication network, there will be great increasment in volumn, power consumption and cost of the optical communicaiton system if we still adopt the traditional discrete way to manufacture the key device of the optical network. Photonic integrated circuit (PIC) technology which can realize several fuctional optoelectronic device in a single chip is considered to be the most likely method to solve this problem. The Infinera Corporation of the USA has realized the first commercial 10×10Gbit/s PIC chip, which marks the beginning of the PIC commercialization. Due to various reasons, research of the core PIC chip starts relatively late in our country. The high-end PIC chip depends on import. Hence, it is exigent to realize the laser chip with low cost and high performance in our country.In this thesis, my research is mainly based on the reconstruction-equivalent-chirp (REC) technique.First, the basic theory of the REC technique is introduced. The coupled-mode theory and transfer-matrix method is used to simulate the 1.3μm DFB semiconductor laser and verifies the possiblity of the specially designed pattern to equivalently realize the performance of the actual grating. And based on this, the author realizes the 1.3μm DFB semiconductor laser and laser array based on the REC technique. Moreover, some research on the follow-up process is done, which lays a good foundation for autonomously realizing the DFB semiconductor laser based on the REC technique.The meaningful results in this work are in the following:1. Coupled-mode theory and transfer-matrix method are introduced and used to study the DFB semiconductor laser. According to the coupled-mode theory, only the interaction between the forward-propagation mode and the backward-propagation mode is considered. In the transfer-matrix method, any waveguide grating can be viewed as a cascade of many uniform grating segments. Thus the effect of the whole waveguide grating on the light can be represented by multiplying the optical matrices of the uniform grating segments orderly. When the parameters, such as optical gain, detuning factor and coupling coefficient change along the laser cavity, the characteristcs of the DFB laser can be solved by the coupled-mode theory combined with transfer matrix method.2. Some special types of 1.3um DFB semiconductor laser based on the REC technique are studied. The feedback effect of mirror loss of λ/8 phase-shifted DFB semiconductor laser is discussed. The simulation result shows that the lasing wavelength of λ/8 phase-shifted DFB semiconductor laser shifts to the long wavelength side of+1st sub-bragg wavelength with the increasement of the coupling coefficient. Several special types of DFB semiconductor laser based on the REC technique are fabricated, such as 1/8 phase-shifted、three phase-shifted、asymmetric phase-shifted DFB semiconductor laser. The experimental results demonstrate the inhibiting ability against the spatial hole burning effect of the 3PS DFB semiconductor laser. The slope efficiency of the fabricated APS DFB semiconductor laser is 20% larger than the SPS one. Moreover,20nmx4 wavelengths and 4nmx20 wavelengths λ/4 phase-shifted DFB semiconductor laser array with high wavelength precision are demonstrated using the REC technique and this is the largest wavlength bandwidth realized with the REC technique, covering nearly the whole O-band. A 10nm×8 wavelengths λ/8 phase-shifted DFB semiconductor laser array with precise wavelength is demonstrated using the REC technique with the residual wavelength within ±0.35nm. An eight-wavelength 3PS DFB laser array with buried-heterostructure (BH) for DWDM syestem is also demonstrated with the residual wavelength within ±0.1nm and this is the first time to realize such 3PS DFB laser array with good wavelength precision for DWDM system.3. After package, the modulation and transmission characteristcs of the fabricated DFB laser is measured. The 3dB modulation bandwidth of the A/4 phase-shifted DFB laser is 14GHz at the bais current of 55mA and the 3dB modulation bandwidth of the λ/8 phase-shifted DFB laser is 13 GHz at the bais current of 40mA, which satisfies the lOGbit/s transmission requirement. The measured IP3 value of the λ/4 and λ/8 phase-shifted DFB laser is 19.8dBm and 19.3dBm, respectively. The SFDR value is also measured, which is 86dB/Hz2/3 and 87 dB/Hz2/3 for the λ/4 and λ/8 phase-shifted DFB laser, respectively, which is nearly the same as that of the commercial DFB laser. Moreover, the lOGbit/s transmission of the fabricated DFB laser after 13.5km single-mode fiber without any dispersion compensation is demonstrated.4. The follow-up fabricaiton process of the REC-based DFB laser is studied, inchluding the photoetching process, etching of the ridge waveguide, "opening" of the SiO2 waveguide, positive and negative electrode process, back thinning process and so on. And the dry-etching and wet-etching process of the ridge waveguide is mainly studied. DFB laser with our own fabrication process is realized for the first time, with its threshold current and slope efficiency around 20mA and 0.1mW/mA respectively, Study of the follow-up fabricaiton process of the REC-based DFB laser also lays a good foundation for the development of PIC chip.