**Part 1**

**Photonic Crystal Laser and Photonic Crystal Characterization** 

**1** 

**Angular-Resolved Optical Characteristics and** 

**Threshold Gain Analysis of GaN-Based 2-D** 

**Photonics Crystal Surface Emitting Lasers** 

Peng-Hsiang Weng1, Hao-Chung Kuo1 and Shing-Chung Wang1

Photonic crystal (PhC) surface emitting lasers (PCSELs) utilizing Bragg diffraction mechanism have considerable amounts of publication during the past few years1,2,3,4. Such PhC lasers have many excellent advantages to attract the attention especially in controlling the specific lasing modes such as longitudinal and transverse modes, lasing phenomenon over the large area, and narrow divergence beam. Therefore, we fabricated the GaN-based PCSELs devices with AlN/GaN distributed Bragg reflectors (DBR) and analyzed the PhC laser characteristics caused by the surrounding PhC nanostructure. However, there were many theoretical methods calculating the photonic band diagrams and the distribution of electric or magnetic field of the PhC nanostructure in the past few years, such as 2-D plane wave expansion method (PWEM)2,5, finite difference time domain (FDTD)6,7, transfer matrix method, and multiple scattering method (MSM), etc. Many different advantages and limitations occur while using these methods. Therefore, in our case, we applied the MSM and PWEM to calculate the PhC threshold gain and photonic band diagram by using our

In this chapter, the fabrication process of PhC lasers will be introduced in section 2. They can be divided into two parts, the epitaxial growth and the device fabrication. Section 3 will show the the foudamental mode characteristics of PhC laser, such as laser threshold pumping power, far-field pattern, MSM theoretical calculation methods, and divergence angles. Section 4, in the Bragg diffraction mechanism, each PhC band-edge mode is calculated and exhibits other type of wave coupling mechanism. Section 5, the photinc band diagrams of foundamental and high order lasing modes can be observed by the angular-resolved μ-PL (AR μ-PL) system. Comparing with the theoretical calculation resulted by PWEM and the experiment results of photonic band diagrams measured by AR μ-PL, they can be well matched and show the novel PhC characteristics. Besides, the

fundamental and high order PhC lasing modes would be calculated in this section.

**1. Introduction**

PCSEL device structure.

*1Department of Photonic and Institute of Electro-Optical Engineering* 

Shih-Wei Chen1,2, Tien-Chang Lu1, Ting-Chun Liu1,

*National Chiao Tung University, Hsinchu 2Green Energy & Environment Research Labs Industrial Technology Research Institute, Hsinchu* 

*Taiwan, R.O.C.* 
