Operation of photonic crystal membrane lasers above room temperature

Abstract

Operation of photonic crystal lasers for substrate temperatures as high as 50°C is reported. The temperature dependence of the lasing wavelength and the threshold pump power is also investigated. The characteristic temperature T o is 37.7 K. © 2002 American Institute of Physics. ͓DOI: 10.1063/1.1517409͔As a promising source for optical communication systems and integrated photonic circuits, the research on twodimensional ͑2D͒ photonic crystal defect lasers has been attracting increasing attention. Single-defect photonic crystal lasers were first demonstrated in pulsed mode at low temperatures.1 Room-temperature pulsed operation has since been demonstrated in lasers with larger mode volumes, [2][3][4][5] and continuous wave room-temperature operation has been reported in a photonic crystal laser with a fusion bonded substrate that had a layer that was subsequently converted to Al x O y . 6 Here, we present the experimental results of pulsed operation of optically pumped photonic crystal lasers above room temperature and characterize the thermal behavior of these lasers.The resonant cavity is formed by removing 19 air holes from a 2D triangular lattice photonic crystal patterned into a semiconductor membrane, which consists of four 10 nm compressively strained InGaAsP quantum wells as the gain media. The laser structure is fabricated by perforating holes through the 224 nm thick membrane by a series of dry etching and wet chemical etching steps.7 Figure 1 shows a scanning electron micrograph of the oblique view of a column of laser structures with a V-shaped undercut groove.The fabricated sample is mounted on a piece of copper, which is fixed onto a Peltier thermal electric cooler ͑TEC͒ with a heat sink attached. The assembly is then mounted on an X -Y -Z stage. A 10 k⍀ thermistor is used to monitor the temperature of the sample. The temperature is controlled by a temperature controller, which has a stability of Ϯ0.004°C. The membrane defect cavity is optically pumped by an 865 nm top-emitting vertical-cavity surface-emitting laser ͑VC-SEL͒ at normal incidence. A pump spot size of approximately 4.5 m is achieved using a long working distance 100ϫ objective lens. A multimode fiber is used to collect the light output from the defect laser and is connected to an optical spectrum analyzer for characterization.The spontaneous emission spectrum of an unpatterned area ͑without air holes and undercut structure͒ shows a broad spectral emission peaked at 1.55 m with a full width at half maximum of 200 nm after the device fabrication process. When the pump beam is moved to and focused onto the defect cavity, we can expect that the temperature of the defect cavity will be higher due to low thermal conductivity of the air region below the membrane. As a result, the gain spectrum shifts to longer wavelength and so does the lasing wavelength.To predict the temperature of the defect cavity under optical pumping, a heat transfer analysis using finite element method is performed. Here, we simulate heat conduction of the photonic cr...

Threshold dependence on the spectral alignment between the quantum-well gain peak and the cavity resonance in InGaAsP photonic crystal lasers

“…We note that even though there is a strong threshold dependence on the spectral alignment between the gain peak and cavity resonance, this effect does not dominate the temperature dependence of the lasers, owing to the small value of T 0 . The T 0 value extracted from this threshold data varies across the array from just under 10 to 21 K. These values are smaller than those in our previous report, 7 but we note that the optical pump spot size and the pulse conditions used in this work differ from the previous work.…”

Fabrication and characteristics of two-dimensional quasi-periodic photonic crystal lasers

“…3 and 4. The smaller cavity is first rolling off due to serious thermal effect [5]. Fig, 4 shows the ultra-low threshold pump power, 0.186 mW, for D2 QPC laser, and slightly higher threshold, 0.246mW, for D3 QPC laser.…”

High frequency oscillation in photonic crystal nanolasers

“…One of the first devices based on localization of light in optical nanocavities was the photonic crystal laser, 14 described by several groups. [15][16][17][18][19][20][21] Here we show modulated oscillations in such lasers of up to 130 GHz from our frequency domain measurements.…”