PAM-XIAMEN is able to supply epitaxial growth service for photonic crystal surface emitting laser (PCSEL), take the following epi structure for example. Also, we can do customized structure growth of PCSEL laser at any wavelength to meet your application needs. Photonic crystal surface-emitting lasers are an integration of vertical cavity surface emitting lasers (VCSELs) and edge emitting lasers (EELs). VCSELs are sturdy and durable, but their wavelength range and power are not ideal; EELs have a wide wavelength range, but their manufacturing cost is high and they are fragile. PCSELs integrate the two, making them complementary to each other.
1. PCSEL Heterostructures
|Layer No.||Layer Name||Material||Thickness|
|8||Contact layer: n||InGaAs||–|
|7||Cladding Layer: n||InP||80nm|
|4||Cladding Layer: p||InP||–|
|2||Cladding Layer: n||InP||–|
Structure 2: PAM211119-LD1550-HP
Structure 3: PAM211119-LD1550-PIN
|N+ InP Substrate|
2. What Is a Photonic Crystal Surface Emitting Laser?
Since the development of semiconductor photonic crystal laser, the common types can be roughly divided into two categories:
1) Photonic crystal defect lasers: its resonant cavity mode is designed within the optical energy gap, so light cannot exist outside the defect area, making light only resonate in this defect area to form photonic crystal defect lasers. This kind of photonic crystal laser can obtain higher quality factor, smaller mode volume, larger Purcell effect and lower threshold conditions.
2) Photonic crystal band edge laser: which operates on flat band edges. Due to the group velocity of light waves approaching zero at the band edge, standing waves are formed under specific Bragg diffraction conditions. Due to its specific Bragg diffraction characteristics, light at a specific wavelength becomes vertically emitted light due to energy and momentum conservation. Therefore, this type of laser is also known as a photonic crystal surface emitting laser.
3. PCSEL VS VCSEL
PCSEL and VCSEL has similarities in some aspects: both are surface emitting semiconductor lasers that can be electrically pumped and typically emit circular beams with high beam quality. However, there are differences. The most fundamental difference is related to the size of the activity area:
For VCSEL, when single mode operation is required, the diameter of the active region needs to be strictly limited. This usually limits the possible output power to a few milliwatts. The larger the active area, the higher the output power may be, but subsequent spatial multimode operations may occur, resulting in poor beam quality.
However, PCSEL is based on a properly designed photonic crystal structure, which can maintain single mode operation while having a larger active region. Therefore, it allows for higher single mode output power. If sufficient and effective cooling is applied, or pulse operation with small duty cycle is adopted, single mode or at least few modes seem to achieve higher continuous wave output power. The resulting radiance (brightness) is correspondingly much higher than VCSEL, and the beam divergence is very small.
4. Applications of PCSEL
PCSEL has an array structure. The coupler region can be controlled in PCSEL array. The laser beam can be controlled in real-time by electronically adjusting the phase of the coupler area. So PCSEL is suitable for LiDAR applications. When PCSEL is used in a LiDAR system, it does not require an external lens system and its associated complex adjustment processes. This can reduce the cost, weight, and size of the LiDAR system.
Moreover, the advantages of single-mode operation, low divergence angle, high power output and large area of light output make PCSELs very suitable for high density optical storage, micro projector light sources and etc.